Talk:Bicycle brake

This means that tyre, calliper, centre, and fibre are all correctly spelt in this article. Please do not change them. -AndrewDressel (talk) 15:54, 25 February 2010 (UTC)

Airbrake?

I was wondering if anyone had devised an airbrake for a bicycle ? I am a complete technical retard, but thought a simple pump when closed off would stop you quite effectively. Brakes at present rely on friction, therefore subject to wear and tear, heat, failure, whereas an air system would be virtually maintenance-free. In the horrible car industry, they have already developed hydraulic systems for recovering the energy used in braking to be recycled as propulsion. However nothing seems to be happening in bicycle innovations at all.—This unsigned comment was added by 62.253.64.7 (talk • contribs) .

To your credit, your self-assessment is accurate. Where do you plan to fit an air compressor, let alone a pressure regulator and controller on a 10kg bike? ZCryophoenix (talk) 22:27, 12 March 2024 (UTC)

One handed brakes

I removed this section--It appears to me as an ad, rather than real information. One-handed levers have been available for years on tandems, and proper technique (as mentioned below in the article) requires seperate control of front and back. —This unsigned comment was added by 198.208.159.14 (talk • contribs) .

---

One-handed bicycle brakes are a relatively new invention. (See http://www.brakedirector.com for a picture.) They work by providing equalized pressure to both wheels. This provides for a smooth and complete stop.

This kind of braking system is ideal for those who do not have use of both hands or those who need to have a free hand, and it works well on paved surfaces.

It is not meant for mountain biking or trick riding - those types of riding require finer control over braking.

---

Friction and brakes...

User:62.249.214.190 wrote:" Incidentally, a larger pad does not give more friction, but it does wear more slowly ..." It's been a long time since I've done physics, but I'm not sure this is correct. If a pad has more surface area in contact with the wheel it should generate more friction as a whole. Anyone? I'm not sure I have an old physics text to dig up to check this. Wikibofh 20:22, 11 May 2005 (UTC)

A smaller pad builds up more pressure than a larger pad (at the same force). However, other factors apply as well. A larger pad may dissipate heat a little better (this may be an advantage when much energy has to be "wasted", but a disadvantage unter wet conditions - but most heat goes to the disc/drum/rim anyway). Of course there is point where a pad gets too small to allow for effective braking (because it gets ripped apart before it gets a chance to convert kinetic energy into thermal energy). --Klaws 13:22, 18 November 2005 (UTC)

The physics behind this is the force of friction is equal to the coefficient of friction times the force on the surface (normal force). The coefficient of friction doesn't change with surface area and the force is the same whether it is 1 square inch or 10 so the force is the same. Like the above said, there are other factors such as heat dissipation and wear. - Jwink3101

That would be an ideal model with ideal materials (steel to steel). In real life where materials wear, scoure, bend and bind its not so simple and more area does give more braking power. However with bicycle brakes this is negligible unlike with f.ex. tyres (try expaining typical >10m/s^2 decelerations of modern cars with simple CoF). 82.181.150.151 22:51, 30 January 2007 (UTC)

Alan.A.Mick (talk) 14:34, 25 October 2020 (UTC)

Under disk breaks it states "As the pads drag against the rotor, the wheel - and thus the bicycle - is slowed as kinetic energy (motion) is transformed into thermal energy (heat)." This is true of all breaks, not just disk breaks and is redundant with the introduction to the article. I suggest deleting.

Dangerous advice: descending and heat dissipation

In the article, it states:

" The problem is worse when descending cautiously at slow speeds because the brakes are "always on" and the cooling airflow over the rim is insufficient. The risk can be reduced by not over-inflating tyres and adopting an aggressive riding style, only braking for the corners."

This is completely false. The energy contained in descending a hill is proportional to vehicle weight and the height of the hill (none of which one can reasonably change at the time of descent). The POWER supplied by the hill, to the vehicle, is proportional to how rapidly the vehicle descends. If a 275# bicycle/rider combo descends a hill at 2 feet per second (vertically), the the hill is supplying 1HP (746W) to the vehicle, all of which must be turned into friction to maintain speed. If the bicycle is moving TWICE as fast, TWICE the power (2HP) must be dissipated to friction. This naturally results in HIGHER (not lower) brake temperatures.

This is why trucks, trains, and other vehicles that have brakes subject to overheating are limited to lower speeds when descending a hill: descend it too fast, and one can easily overpower the braking system, resulting in a runaway.

Whether "constant-on" braking is better, or worse, than "intermittent" braking is not the issue: descending at a lower speed will result in lower brake temperatures than descent at a higher speed, given a consistent braking strategy.

In addition to the fact the quoted passage violates physics, the fact that it encourages (likely) unlawful speeds in the interest of "safety" is sufficient cause for it to be removed. —Preceding unsigned comment added by 72.95.199.241 (talk) 05:37, 20 April 2010 (UTC)

I agree, and I clicked on the discussion page for that reason. Of course, a faster rider will have a greater percentage of their energy dispersed by drag, so I would guess that at some point faster descents would mean cooler brakes (for example: if you didn't use your brakes at all). However, I'm not at all sure that it would be true in a real life situation, and anyway, encouraging people to descend mountains on bikes faster than they would naturally be comfortable is ludicrous, IMO Kjsharke (talk) 14:37, 6 May 2010 (UTC)

If we assume that the mass of the combined rider and bike at a given altitude results in a fixed amount of ‘gravitational potential energy’ (GPE = mass * gravity * height), and that the rider will come to a stop at the bottom of the slope (has zero kinetic energy), then all of the GPE must be dissipated by some means. Ignoring bearing and tyre friction we are left with two major dissipation mechanisms, braking and aerodynamic drag. Since aerodynamic drag has an approximately squared relationship to speed we can say that a faster rider who only brakes for corners will dissipate more of his energy this way and so his brakes will do less ‘work’ during the descent than the slower rider’s; i.e. they will convert less GPE into heat. However, the slower rider will take longer to descend the mountain than a faster rider, therefore (assuming the rate of heat loss is equal in both cases) his brakes will shed a greater amount of heat energy into the atmosphere in total. The situation is however further complicated as the brakes of the faster rider, who only brakes for corners, will experience large fluctuations in temperature and the rate of heat loss will vary accordingly. 138.38.72.19 (talk) 16:17, 5 January 2012 (UTC)

No it's right - you are ignoring air resistance. That goes up rapidly as a function of speed. The quicker you go, the more power is lost to the air + the less goes to the brakes. On a tandem, the 'stoker' at the rear can sit up and hold her open jacket out as an air-brake - think parachute. On the other hand I knew a tandem rider who would stop every so often on a descent 'to let the brakes cool'. Of course, that dumps all your kinetic energy into the brakes, and then removes the 'forced air cooling'. The result was a smell of burning grease, and disks that boiled water if you spat on them. Let 'er rip - within reason ! --195.137.93.171 (talk) 10:04, 16 April 2014 (UTC)

Plagiarism

Has anyone compared this page at Wikipedia to Sheldon Brown's article about braking techniques?

I've seen better plagiarism in a tenth grader's essay about bicameral legislatures.206.53.17.207 06:11, 18 December 2005 (UTC)

I have my doubts about the section for other reasons. See below. Dmforcier (talk) 22:49, 17 September 2009 (UTC)

Rearrange titles

This article is rather haphazardly divided. I recommend that we organize the order of the types of brakes. How do you recommend? Alphabetically? Chronologically? --Adamrush 16:30, 2 April 2006 (UTC)

Dangerous Advice

The assertion that it is practically impossible to lock up the front wheel when in motion by using the front brake alone is questionable. There have been great leaps forward in bicycle braking in recent times notably the widespread adoption of disc brakes/V brakes that used to be the preserve of higher end bicycles. There are many braking setups that will apply full lock with as little as one finger on the brake lever, so playing down the possibility of going over the bars seems a little ill-considered. —This unsigned comment was added by 217.31.144.38 (talk • contribs) .

I'd have to agree for a different reason. The increasing popularity of front suspension makes going OTB easier than ever--even if one braces oneself properly. However, with unsuspended forks, it's still quite a feat to lock a front wheel with a bicycle brake. --Adamrush 16:54, 6 April 2006 (UTC)

I agree, and I have edited the section to reflect this. From my experience, almost any rider with a V-brake or disc brake system could easily make the mistake of locking up the front wheel and going OTB during a panic stop situation, especially if they weren't familiar with how the bike behaves during very hard braking. -SCEhardT 19:17, 6 April 2006 (UTC)

Question: Oil on the disc brakes? Total devastation or it is possible to clean up? My bike dealer told me they had to replace the new -09 brakes, when the manufacturer had spilled a thin oil film on the disc brakes. True or false, perhaps in the grey? —Preceding unsigned comment added by 81.170.235.91 (talk) 23:44, 17 September 2008 (UTC)

This type of question is better asked at such as bikeforums.net, but the answer is: grey. Metal discs can be cleaned with stuff like automotive brake cleaner. Pads should be replaced. --Dmforcier (talk) 20:28, 30 July 2009 (UTC)

Rim brakes reorg/main article

The section on rim brakes needs a serious reorganization or to be moved to its own article. If the former, I propose that the heading "Rim brakes" be replaced with "Centerpull brakes", "Cantilever brakes," "Caliper brakes," and "Rod brakes." Feedback would be greatly appericiated before I throw this article to the butcher. --Adamrush 13:04, 15 April 2006 (UTC)

Disc brake Disadvantages

The article claims that straight gauge spokes need to be used for disc brakes to do strenghts: "thus ruling out very light and thin double-butted spokes", however straight gauge spokes are weaker than butted spokes.

"Double-butted spokes do more than save weight. The thick ends make them as strong in the highly-stressed areas as straight-gauge spokes of the same thickness, but the thinner middle sections make the spokes effectively more elastic. This allows them to stretch (temporarily) more than thicker spokes.

As a result, when the wheel is subjected to sharp localized stresses, the most heavily stressed spokes can elongate enough to shift some of the stress to adjoining spokes. This is particularly desirable when the limiting factor is how much stress the rim can withstand without cracking around the spoke hole. "

Sheldon Brown - Well respected expert on bicycles

"... double-butted spokes offer superior strength to a straight gauge spoke. The weakest part of a spoke is at the bend, where the spoke enters the hub flange, typically this is where a spoke will break. Because a double-butted spoke has a smaller diameter around the middle of the spoke stresses will be relieved in this area, which translates to less stress at the bend. There are some weight savings in using a double-butted spoke as well, however that's more of a co-benefit of using a double butted spoke. "

[ http://www.winterbornebikes.com/winterborne-custom-wheels Winterbornebikes.com] - Well respected wheelbuilders

I could quote more references... Anyhow please don't undo my edits on the main page to correct this. User:RijilV —Preceding undated comment was added at 05:32, 25 October 2008 (UTC).

I totally agree that Double butted spokes are stronger than straight gauge for all the reasons you state above. But that doesn't make them mandatory for use with disk brakes. They seem to be limited to very high-end handbuilt wheels, and disk brakes are getting pretty common these days. You can get them on a bike for 500$ these days here in Canada, at my LBS, and probably cheaper at a big-box. —Preceding unsigned comment added by Keithonearth (talk • contribs) 07:27, 25 October 2008 (UTC)

What you're not stating is what factor is being kept equal. If the max thickness is equal, removing material from the middle section of a spoke will not make it stronger. For the same weight of spoke (same amount of material), distributing the material so there is more at the point where it is most likely to break will increase the strength. --195.137.93.171 (talk) 10:10, 16 April 2014 (UTC)

Disc brakes and spokes

Can someone clarify this recent addition: Furthermore, a disc brake puts more stress on a wheel's spokes than a rim brake, since the wheel is held only at the hub. Isn't every wheel "held only at the hub", disc or not? The logic here seems flawed. --Ds13 17:10, 11 May 2006 (UTC)

I think that the critical difference between rim brakes and disc brakes, that the addition was trying to convey, is that with disc brakes the torque of braking occurs between the hub and the rim, while with rim brakes the only time torque occurs between the hub and the rim is at the rear hub during pedaling. It is true that rim brakes can work with radial spoke lacing on the front wheel, while disc brakes require cross-lacing (usually 3x). So while the addition was somewhat inarticulately expressed, it is indeed based in fact. Matt Gies 17:25, 11 May 2006 (UTC)

Thanks, that's a great explanation; makes sense. I used your explanation to clarify the article so the question won't come up again. Cheers. --Ds13 19:51, 11 May 2006 (UTC)

I'm curious why you added the "on the front (non-driven) wheel" qualification to radial lacing? Opinions and preferences aside, rear wheels can be radially laced (and even more commonly, half-radial laced on either the drive or non-drive side). Thinking about it, I could probably remove the "lighter" qualification also, since there are coaster-brake equipped bikes that use radial lacing on the rear also. This would usually be done with many more than the usual number of spokes (i.e. heavier), but it's a notable cosmetic trend in bikes. --Ds13 21:16, 11 May 2006 (UTC)

OK, I hadn't seen/heard of rear wheels radial on both sides. I'm actually running a rear wheel with 1-cross on the freewheel side myself right now, just because I was a little reluctant to jump into a radial lacing there at first attempt, but radial on both sides is news to me. You seem to know what you're talking about, though, so I stand educated. Gzuckier 16:25, 12 May 2006 (UTC)

Yes, if you read up on this and talk to builders, there are a lot of conflicting claims. Every combo is out there (some, probably destined to crumple!) Some say "radial lace on the non-drive side for maximum strength" and others say "radial lace on the drive side for maximum strength". They both back it up with their own interpretation of torque and physics. I don't know enough to know who is right, but you can definitely see radial on both sides (usually with high-profile rims). Then there's the 72-spoke full radial scene among low-riders and beach cruisers... Cheers! --Ds13 16:51, 12 May 2006 (UTC)

Braking technique

"The downhill (gravity-provided) acceleration (while braking) can be assisted by pedalling while front-braking for further stability (this counter-intuitive technique of actively pedalling while braking is akin to "left-foot braking" or "toe & heel" in automobile / motorcycle cornering-braking techniques)."

Does anyone know what this is trying to say? The Heel-and-toe article refers only to setting the throttle while braking in order to facilitate shifting. This can't possible apply to cycling, can it?

The Left-foot braking article refers mostly to controlling oversteer. It also cautions "this technique should not be confused with Heel-and-Toe, another driving technique." Is the author of the above quoted sentence advocating causing the rear wheel to slide "for further stability"?

Are there any references for this? -AndrewDressel 03:51, 3 August 2006 (UTC)

None found, so it is out. -AndrewDressel 12:38, 4 August 2006 (UTC)

I really dislike the way this section is written. It should outline the principles e.g. of weight transfer first, then discuss techniques. And distinguish types of bikes more clearly. What works for a road bike may not work for a 'bent or MTB.

Also, I disagree on front braking alone. I find that rear braking in many circumstances is more stable, e.g. when "trail braking" through turns. But then I'm no expert on (bike) dynamics.

Anyone care to tackle this?
Dmforcier (talk) 22:56, 17 September 2009 (UTC)

A lot of this section seems out of whack. It repeatedly says that locking the front wheel causes you to go over the bars, where usually the opposite is true. You usually go over the bars because you have sufficient braking, but too high of a centre of mass to brake at the necessary speed. Locking the front tire will usually result in a crash, but usually it will just be a lowside dump. The nose just goes off to the side and you fall over. Most of the suggestions where to use more rear braking are reasonable, but the included reasoning is flawed. There's 2 reasons to use your rear brakes in poor traction. 1.At maximum front braking without skidding, the rear wheel is probably still on the ground, with a bit of traction remaining to be used. 2.Locking a front tire will very often lead to a crash. With a rear, you can usually keep the bike in line. The bit about "The skidding of the rear wheel can serve as a signal to reduce force on the front brake" may incorrectly imply that the brake balance should be shifted towards the rear. Likely the only way to keep the rear wheel down is by either shifting the rider's weight back, or by braking less hard overall. Sure, reducing front braking will increase available traction on the rear, but no more than the braking power which could have been used on the front. Nwimpney (talk) 04:34, 1 May 2010 (UTC) Locking the front wheel causes a pitchover crash if the traction is great enough -- that is, in straight-ahead braking on a good paved surface. with less traction or when turning, the front wheel will skid, the bicycle cannot be balanced, and it falls to the side. Optimum braking on a conventional bicycle with a high center of mass is achieved when there is very little weight on the rear wheel, hence very low traction. Light use of the rear brake, or continuing pedaling to feel when the rear wheel begins to slip, is the signal to reduce fore on the front brake to avoid pitchover.Jsallen1 (talk) 14:18, 26 September 2018 (UTC)

The whole section as per 2023 fails to explain the front brake is most powerful, and good technique is therefore to let the front brake do more of the work. 80.7.168.14 (talk) 18:25, 20 July 2023 (UTC)

Historic Disc Mounting Standards

Prior to the 6 bolt ISO standard and the Shimano Centrelock standard Hope Technology [1] used various mounting systems:

• 6 bolt mount (non ISO pattern) circa 1991-1993

The disc mounted directly to the hub as per current ISO standard.

• screw on Spider circa 1992-1994

The disc mounted to a separate spider that was screwed onto the hub.

• 15 spline interface circa 1994-

Hope 15 Splined Hub/Spider

• 5 spline interface years unknown

(hub compatible with the 15 spline spider)

Hope 5 Splined Hub/Spider

• 6 spline interface 1996 - (years of use unknown)

File:Hope6splines.jpg

Hope 6 Splined Hub/Spider

Nick 3216 17:10, 3 August 2006 (UTC)

FGs have a brake!

As most legal authorities (I know of UK and US statutes) consider a fixed gear arrangement to be a brake and Merriam-Webster defines brake as anything used to restrain motion, I'd sure like to see FGs included here as a bicycle braking system. Further, references to FGs not having a brake should be thusly edited. - 01:27, 15 June 2007 Taisau

Actually FGs have two brakes: 1) dragging your feet (dangerous but included); 2) back pedaling (!?!) - essentially, skidding the rear tire - typically something one wants to avoid. I see no reason to include it.

BTW, in UK it is illegal to ride on the road a bicycle with no brake. Are you saying this doesn't apply to fixies? Got a statute or ruling reference? Dmforcier (talk) 18:21, 10 April 2014 (UTC)

in the UK you must have two *independent* braking systems; on a fixer or other direct-drive machine the transmission counts as one. Of them. This is also the reason for the crappy spoon parking brake on the Windcheetah recumbent trike as its front brakes are both operated from a single lever. Mr Larrington (talk) 05:53, 6 October 2014 (UTC)

This case pretty much sums ip the UK situation; "'Dangerous' cyclist killed pedestrian then blamed crash on her, court told.

Charlie Alliston had been riding fixed-gear track bicycle with no front brake, which is not legal on road without modification" [[2]] 80.7.168.14 (talk) 18:34, 20 July 2023 (UTC)

bent rims and dual pivots

"if the rim has a pronounced wobble, then either the brake pads rub against it when the brakes are released, or apply insufficient and uneven pressure to the rim when certain brakes e.g. dual pivot, are applied."

What, specifically, about daul pivots vs other rim brakes is the issue with a bad rim? -AndrewDressel 22:28, 23 October 2007 (UTC)

Apparently it's because the two calipers (the part where the pads fit to) don't follow an out of true rim, whereas a single pivot will. I could be wrong about the dual pivots, I've never even used them, but I do know the two calipers on a SP will move side to side as a unit ie if you remove the wheel and apply the brake as normal then push one of the brake pads sideways, the other pad will move in the same direction and by the same distance, so braking is not greatly affected by an out of true rim. I don't know if this the case with DPs. Or perhaps it's to do with DPs' higher mechanical advantage, so the pads have to be set closer to the rim, so you need a truer rim. Please go ahead and correct any mistakes. LDHan 00:53, 24 October 2007 (UTC)

Disk brakes: ISO vs Post Mount

I have the impression that bike shops like post mount as the ease of setup reduces their service time/costs. On hydraulic brakes, you loosen the screws, pump up the brakes and tighten down the now-centred unit. As usual, I have no citation for this. SteveLoughran 22:07, 9 November 2007 (UTC)

I don't find it makes a difference for adjusting the brake, if it's ISO or Post. If it uses ISO tabs, then there is just an additional bolt that you don't need to touch if you're adjusting the brake. In theory on either with hydraulic you should be able to (as you say) "loosen the screws, pump up the brakes and tighten down the now-centred unit." In practise it doesn't always work as it should. I should specify that I'm talking about callipers that bolt on to a bracket, instead of directly onto the tabs.--- Keithonearth (talk • contribs) 01:06, 30 November 2008 (UTC)

"Power Sliding"

If there are no objections, this should be removed. This section describes something that is simply skidding, it has NOTHING to do with power applied, just mis-use of brakes and very bad trail etiquette. On Concrete/tarmac it damages the tyre and it damages the trail offroad. 86.148.87.188 (talk) 19:38, 27 January 2008 (UTC)

Rim Brake Advantages and Disadavantages & Drag Brake

In the subsection "Rim Brake Advantages and Disadavantages" under the section "Rim Brakes", it states "But on heavily-laden touring bikes and tandems in mountainous regions, the heat build-up can increase tire pressure so much that the tire blows off the rim." Again in the subsection "Drag Brake" under the section "Drum Brakes", it states "Such brakes occur on some tandem bicycles used in mountainous areas, where extended use of rim brakes can cause the tire to become hot enough to explode." Is this true? I've never heard of this, I'm not sure I believe it, and would like to see a citation for this "fact". I would think that the brake pads on rim brakes would soften and wear away long before the tire got "hot enough to explode". Also, if it is necessary to "ride the brake" for a long period of time, wouldn't that indicate that you were descending a trail that was too steep for your ability, and that you probably should not be there? 168.103.134.214 (talk) 20:16, 18 May 2008 (UTC)

Sheldon Brown says "A brake that can be set so that it will stay on even when the rider lets go of the control lever. This is usually a drum brake operated by a friction-type shift lever. Tandems are often equipped with a drag brake when they are to be used for touring in mountainous terrain. This is because descending with a heavily-laden tandem using rim brakes only can cause the rims and tires to overheat, leading to blowouts." -AndrewDressel (talk) 01:33, 19 May 2008 (UTC)

Tubular tyres are more prone to this as the heat will cause the glue holding the tyre to the rim to soften Nick 3216 (talk) 20:17, 14 July 2008 (UTC)

Yes, it is a problem. If you have access to suitable archives, many years ago Bicycling Magazine had a time-lapse photo sequence of a tandem on a downhill blowing off the front (clincher) tire and the riders falling; one broke his collarbone, I forget the others' injuries. Blowoffs are usually when the bead of the (clincher) tire comes off the rim, though a weakened tire casing can also tear through, as elevated temperatures increase tyre pressure and this combines with hard braking to accelerate failure of the weak casing. Finally, the tire may "creep" relative to the rim and tear off the valve stem, causing the tire to deflate and then it can come off the rim, though in this case there is no "bang!", as tire pressure went down first and the tire came off second. The mechanism of blowoffs, by which the bead gets off the rim, is not well understood. Experimental data collected recently by Brandt et. al. suggests the increase in tire pressure is typically modest compared to the test pressures at which cold tires blow off. It may be the increase in temperature causes increase in lubricity at the bead/rim junction allowing other forces to push the tire off, but at present that is speculation. Nonetheless, there is a long history of blowoffs, and the standard approaches are to change riding habits and/or fit a third drag brake so less energy is dissipated through the rim.

Riding the brake may be a reflection of rider skill, but may also simply reflect necessary braking for the road or trail conditions. And if a rider can descend successfully by riding the brakes, then apparently the descent is within the rider's abilities. At any rate, riding the brake would normally be expected to lead to brake wear, not cause catastrophic tire failure, so it is important to note the failures. —Preceding unsigned comment added by Pardo (talk • contribs) 22:29, 3 February 2010 (UTC)

I agree with the recent edits on this subject, but reviewing the section I found problems that parallel those found in the similar Disc brakes Advantages and disadvantages section.

• Organization. It jumps back and forth between issues. [fixed, I hope]
• Lots of equivocation and subjunctive mood. [improved, I hope]
• It tends to be a dumping ground for unencyclopedic content.
• Off-topic text. E.g. there 's a large paragraph on brake pads that has little to do with "Advantages and disadvantages". [fixed, moved to a new section]
  • There's a paragraph on Bowden cables that really doesn't belong in a discussion of Rim brakes - other systems also use Bowden cables. In fact, I'd just remove the whole paragraph and refer to Bowden cable article for such discussion. Or move it to its own section. (Maybe we need one on Maintenance?)
• There may be unmentioned topics that belong in Advantages and disadvantages. Glaze on rim and pad; difficulty adapting to suspensions; lower cost and weight. Possibly others. Dmforcier (talk) 22:02, 6 May 2010 (UTC)

And just to add to that, i do think that yep. —Preceding unsigned comment added by 76.118.247.225 (talk) 10:47, 17 June 2010 (UTC)

National variety of English

This article was started using British English. It evolved over time to be a mix of US an UK English, and recently was changed to be pure US English. While I don't really care if this particular article is in US or UK English, I'd hate to see all wikipedia use US English. (Or even for all things that are not specifically non-US. If that makes sense.) I'd prefer to see this article in UK English. Anyone other opinions? --- Keithonearth (talk • contribs) 00:59, 30 November 2008 (UTC)

By 22:42, 16 November 2004, when Sfahey "moved stuff from main page", it was all American English. I picked the one that matched the main bicycle article and required the fewest changes. -AndrewDressel (talk) 04:48, 30 November 2008 (UTC)

i totally agree about it being preferable to be in one type of English, all I'm saying is that I'd prefer to have it be uk.en. I didn't know that it's relevant what the main bicycle article is written in, I thought it was just based on what variant the article was started in. I'm happy to go threw and change it all to uk.en, but wanted to talk about it first. To clarify do you want it in us.en, or is your only goal to have it consistent?--Keithonearth (talk) 19:03, 30 November 2008 (UTC)

Although Wikipedia:Manual_of_Style#National_varieties_of_English doesn't comment on a group of related articles, it does state "if an article has evolved using predominantly one variety, the whole article should conform to that variety, unless there are reasons for changing it based on strong national ties to the topic." I guess I have to admit that my personal preference is to have it in American English, but my main goal is to have it be consistent. -AndrewDressel (talk) 20:01, 30 November 2008 (UTC)

Looks like UK english back to the first edition, which uses Aluminium over Aluminum, and there's later corrections over the spelling of Disk, correcting to en_gb form: Disc. Indeed, the article Disc Brake uses the UK spell in its title. Looks to me like the UK spelling has historical right of way. That said, it is a mess. Caliper over Calliper, for example. If the page is to stay UK-english, it needs proofing. SteveLoughran (talk) 15:25, 1 December 2008 (UTC)

I'm the same as you Andrew, my main goal is to be consistent, but in this case I do think en_gb makes sense. I'm happy to proof it and change it to en_gb unless there are objections. No time now, but maybe this evening.

OK, done. Or at least I think I got everything.

greying the background of images

I've just put some work into greying out the background of a couple of the images. I'm really happy with the way the single pivot calliper turned out, and not so happy with the way the V-brakes turned out. The problem with the V's in my mind is all the blue reflected in the arms of the brakes from the frame paint. I may redo the V's, but I'll do some of the others first. That is, unless people don't like the idea, I'd hate to do a bunch of work and then have it not used. Anyone not like this idea?--Keithonearth (talk) 07:54, 8 January 2009 (UTC)

Looks sharp to me: very striking. What app do you use to do it? -AndrewDressel (talk) 12:06, 8 January 2009 (UTC)

I also like the way it looks - I think it really helps to define the part to people unfamiliar with it. I did something similar with Bowden cable a while back. If you have problems with a grey part blending in to the greyed-out background, a colored background might help (for example with File:Pedderson-bremse.jpg) -SCEhardT 16:40, 8 January 2009 (UTC)

Thanks for the positive feedback. I'm using GIMP to do the image editing, I like working with it. A coloured background is a good idea to get around the already grey brakes, but I would like to see them look consistant, both in regards to background colour, and ideally the angle of the viewer. I don't have a fancy camera, but I do have access to lots of bikes so I may be able to get a shot of high profile canties that fits both criteria. I notice the centre pull brakes were uploaded by you Andrew, do you have a higher resolution version of the centre pulls? And/or would you mind taking another photo of the dual pivot? I was thinking more level would make it easier to compair with the single pivot. Of course that would mean the way the arms overlap would not be visible, but I think it would be a worth while trade. You?-Keithonearth (talk) 09:09, 9 January 2009 (UTC)

Delta brake

The article references to Delta Brakes, and goes on to describe something that sounds nothing like what I know as Delta brakes. To my knowledge "Delta brake" refers exclusively to a type of brake manufactured by Campagnolo (maybe trademarked). It's a pretty obscure design. Like the one described the cable pulls from the centre, but the similarities end there. For a nice change I have references this time, Jobst Brandt agrees as does Jan Heine in the latest issue of Bicycle Quarterly. The ones described seem to be Shimano's aerodynamic" Dura-Ace AX (early 80's -- a more obscure design). If no one objects I'll rewrite the section.--Keithonearth (talk) 21:51, 20 January 2009 (UTC)

Ok, I got solid references, so I rewrote it, without waiting around much. That said, this section seems a bit unnecessary, it's such an obscure brake. I'd be happy to see it removed. --Keithonearth (talk) 08:44, 22 January 2009 (UTC)

Good refs. I did a bit of a rewrite to separate the "what is it, how does it work" info from the "history" info. (Also as a test of removing the wikitables - see below.) IMO we should keep the section. I don't know of any policy against completeness. ;) --Dmforcier (talk) 15:39, 31 July 2009 (UTC)

I'm with you on that. -AndrewDressel (talk) 16:18, 31 July 2009 (UTC)

Disc brake advantage

Does Jan Heine in the reference cited really say "Disc brakes can operate with a higher mechanical advantage than rim brakes, as the rotor is more perfectly straight than a rim, and the pads do not need to move as far on release." I don't have a copy and so can't check. My experience in the shop is that discs don't run that much truer than good rims. I would suppose instead that discs can withstand higher pressure, provided by cable or hydraulic systems, because they are solid steel disks instead of aluminum or carbon fiber box sections. -AndrewDressel (talk) 23:18, 20 January 2009 (UTC)

The quote is: "A small disc provides less leverage than a large rim, so the brake must have much higher mechanical advantage. By squeezing the disc much harder than a rim brake squeezes the rim, the disc brake better is able to scrape water off the disc in the wet. However, the pads must be very close to the disc, and often rub if the disc is slightly out of true." So no, nothing about the trueness, it was the higher mech advantage and the removing water that I was referencing. (Is there a way I could make that more clear in the article?) However, my experience is the trueness of a disc in good condition is better than a well trued wheel. A disc in poor condition could be worse than a well trued wheel. The tools used for the wheel and disc illustrate this. (these are the ones we use at the shop I'm at) The callipers on an ordinary truing stand don't give any feedback other than by eye and ear. The gauge used to measure the trueness of a disc is far more accurate, working like a dial calliper.

I think you do have a point about the fact that a disc is solid, a rim not. It seems to make sense but I've no idea if it's true or just makes sense.

(I just got a subscription to Bicycle Quarterly it's a great magizine, focused on Randonneuring but lots of good info, I'd totally recommend it.) --Keithonearth (talk) 07:52, 22 January 2009 (UTC)

Cool. I'd try to stay closer to what the source says with something like this: "Because of the smaller radius of a disc, compared to a rim, disc brake calipers must generate more force to produce the same braking effect, and this greater force does a better job of clearing water from a wet disc. The greater force requires more mechanical advantage which, in turn, requires that the pads be positioned much closer to the disc in the relaxed position than the pads of rim brakes."

While the tools for measuring trueness of discs may be fancier than for rims, the tools for improving trueness are not. The best I can find is the Park disc truer which isn't much better than an adjustable wrench. -AndrewDressel (talk) 14:55, 22 January 2009 (UTC)

Ok, I changed it to make it clear that the statement that rotors are more true than rims is not is not referenced. That said I do believe it's true, the park tool that I use (see above) measures in 1/100ths of mm, I expect to get a rotor within 0.05 mm of trueness on a rotor that's in reasonable condition, or 0.1 to 0.15 on one that's taken some hard knocks. Beyond that I recommend replacement. On a rim I expect to get it within 0.5mm on a new wheel build, and <1mm on a wheel that's been ridden, (or even as much as 3mm on a wheel that's old and expecting to be replaced soon). You are right the tools used for bending the rotor are crude, but with quality feedback, quality results are attainable.

Anyways, I don't have a reference yet, put up a {{fact}} if you feel the need. I'll look for a reference either way, but it's not the highest priority for me, as the main thing is that disc brakes do use a higher mech advantage, and that's solidly referenced. And self evident, as if they didn't they would work more poorly than rim brakes due to lower leverage. --Keithonearth (talk) 07:29, 23 January 2009 (UTC)

They do - must - use a higher mechanical advantage, but that does not imply, as is claimed somewhere in there, that they require less operator input for the same stopping force. Nor, for that matter, that they have "superior modulation". I want to see some references. Dmforcier (talk) 02:44, 9 February 2010 (UTC)

"Disc brakes are able to operate at a higher mechanical advantage than rim brakes because disc rotors in good condition are more true than rims in good condition, and thus do not need to retract as far from the rim when released" That sentence is a mis-statemant. Pads run closer to the disc because they have to. Disc brakes require a higher mechanical advantage so the piston has a shorter maximum throw (how far it moves with a full swing of the lever) than a rim brake cable. No one can make such a grandiose statement as "discs are truer than rims", but it doesn't matter because that is unrelated to the point. I know that there's a citation on it, but quoting nonsense makes it none the less nonsense.
Dmforcier (talk) 02:57, 9 February 2010 (UTC)

Maybe the advantage of disc brakes is that you can put way more force on the rotor without damaging it. Whereas you can apply enough force from cantilever or other rim brakes to damage (worn) rims. I know this from personal experience, though I suspect the age/state of the rims were the primary cause. As disc rotors are solid, I don't see it being possible to crush them.

Other thoughts (again, experience, risk of personal research)

1. What advantages do hydraulics offer? You can get hydraulic rim brakes and cabled disc brakes, so there should be some data.

2. Does the requirement to dish the front wheel reduce its strength, or just make spoke tightening trickier?

3. Heat dissipation issues. Rotors do get so hot they glow, -but it does't matter. Whereas coming off Hardknott Pass I did experience the pads on my rim brakes melting as the first sign of an overheating rim. There are claims that tyres can explode/melt too, but that may be a road bike event not an MTB one, not something I've experienced. SteveLoughran (talk) 22:31, 21 February 2010 (UTC)

One can generally apply more force to a rotor than to a rim. But that may not be significant in practice: the rotor is a shorter lever arm so a higher force is required to achieve the same stopping power. However, this question is largely irrelevant. The limit on stopping power is rarely the brake, but rather tire adhesion and (hopefully beyond that) the amount of force that produces an endo. If the disc brake has an advantage here, it is minor at best.

1. Depends on the design. There's nothing inherently better about either.

2. Both.

3. Agreed, and it is in the list.

Dmforcier (talk) 18:50, 25 February 2010 (UTC)

New name

the name of this article should be changed to cycle brake systems since it talks about trikes too. Username 1 (talk) 20:14, 5 June 2009 (UTC)

That seems unnecessary to me. --Keithonearth (talk) 18:10, 30 July 2009 (UTC)

why tables?

A number of the brake types have been put into tables, I'm not sure why this was done. It's not been done for all the brake types, but only the ones that have pictures. This seems unnecessary and makes the sections on brakes that we have a picture for and the ones that we don't look very distinct from each other visually, this seems undesirable to me, and I don't think it's common practise on WP to do this. (Or am I missing something?) I'd like to remove the tables, any objections? --Keithonearth (talk) 18:20, 30 July 2009 (UTC)

It too was wondering about that. Perhaps the contributor was unsure how to align pics to headings? I vote to go to a more standard style. --Dmforcier (talk) 19:16, 30 July 2009 (UTC)

FYI as a test I tried pulling the wikitable from the Delta brakes section. Since the text is relatively short the next section begins in the middle of the pic. If there's a better way to control how the sections respect the pic, I don't know it. Let us know what you think - is this a better way? (Please don't do a straight revert if you decide to keep the wikitables - I made some editorial changes too.) --Dmforcier (talk) 21:32, 30 July 2009 (UTC)

I couldn't stand the tables any more and finally got rid of the last of them. Here is a tutorial on how to deal with picture stack-up http://en.wikipedia.org/wiki/Wikipedia:PIC I think it looks better now.
--Dmforcier (talk) 00:27, 14 August 2009 (UTC)

Thanks for doing that, the new layout looks way better to me.--Keithonearth (talk) 00:47, 14 August 2009 (UTC)

Phew! Thanks for getting rid of them! -AndrewDressel (talk) 02:24, 14 August 2009 (UTC)

Calliper?

My dictionary does not list "calliper" as an alternate spelling of "caliper", though I see that several online dictionaries do. You can change it back if you want, but it still looks wonky to me.

Btw, sorry about "centre". I was unaware of the policy on alternate spellings.
--Dmforcier (talk) 19:13, 30 July 2009 (UTC)

Calliper is the British spelling, as can be confirmed at dictionary.cambridge.org -AndrewDressel (talk) 19:37, 30 July 2009 (UTC)

Oh maybe that's it. I gotta use a British dictionary. :D --Dmforcier (talk) 20:23, 30 July 2009 (UTC)

That is definitely it, along with centre, tyre, fibre, aluminium, license, etc. You can check out American and British English spelling differences for more details. -AndrewDressel (talk) 21:36, 30 July 2009 (UTC)

So, is it 'Direct pull' or 'Linear pull'?

The terms are used both as if there is a distinction between the two, as in the section title "Cantilever, direct-pull, and linear-pull brakes". Yet there is no subsection for Direct pull. Elsewhere the two terms seem to be used interchangeably for the V-brake design. Sheldon understands them to be synonyms. "Linear Pull Brake - Another term for a direct-pull brake. "

Everyone seems to refer to them as V-brakes, but I know we can't use that. So what should it be? One or the other (and not both)?
--Dmforcier (talk) 23:04, 1 August 2009 (UTC)

I considered changing the Rim Brakes heading outline to add a new level:
-Rim Brakes
--Caliper Brakes
---Single Pivot ...
---Dual Pivot ...
--Cantiliver Brakes
---Traditional
---V-Brakes
---Roller Cam
but I don't think it adds much, and complicates the juxtaposition of the nearly identical Caliper and U-brake. So I think I'm going to use a flat list instead:
-Rim Brakes
--Caliper Brakes
--Single Pivot Caliper Brakes
--Dual Pivot Caliper Brakes
--Traditional Cantiliver Brakes
--V-Brakes
--Roller Cam
And I'm just going to go ahead and use "V-Brakes" in the heading. If this it wrong speak now or forever hold your piece.
--Dmforcier (talk) 20:31, 13 August 2009 (UTC)

Just to complicate matters: V-brake is or was a trademark, which was why the terms "linear pull" and "direct pull" were introduced.

Also, calliper brakes (arguably) include single-pivot sidepull, dual-pivot sidepull, and center-pull. The center-pull brake and the U-brake are indistinguishable mechanically, but the U-brake uses the frame as the calliper portion.

Finally, some brakes use a conventional linkage with a different cable routing. For example, the Scott Superbrake is a sidepull but with the arms in an X so the cable routes across the top; and some BMX and triathalon brakes are shortend to clear the down tube, for instance a dual-pivot "side pull" with the cable routed funny or a U-brake with no straddle wire and instead the cable pulls between the two arms.

Nomenclature!

... put their legs over the handlebars they would be launched feet-first ...

The History section includes:

“ The earliest bicycles braked using the rider's leg force to resist the pedals ... larger wheels meant less leverage ... and riders were often thrown head-first ... leading them to put their legs over the handlebars so they would be launched feet-first instead of head-first. However, this meant removing the rider's feet from the pedals, and thus required a mechanical brake. ”

This doesn't make sense. If their feet were removed from the pedals and put over the handlebars, then they were not braking at all - but if they're not braking, how are they thrown over the handlebars? I find it difficult to believe that the riders used their legs to brake sufficiently hard for them to be thrown over the handle bars and then put their legs over the handlebars to avoid being thrown head first. I think a re-write of this paragraph is required. Mitch Ames (talk) 03:03, 3 February 2010 (UTC)

Hmmm. Also, David Herlihy, in Bicycle, The History mentions on page 76 that Michaux velocipedes had spoon brakes in the 1860s, before the advent of the high-wheeler. -AndrewDressel (talk) 03:52, 3 February 2010 (UTC)

The recent change to the article to link to Penny-farthing#Operation doesn't resolve the problem, so I've re-inserted a {{clarify}}. If anything the link confuses things, because Penny-farthing#Operation doesn't state that the "feet over the handle bars" was to allow them to come off feet first - it says it "made for quick descents" implying that it allowed the pedals to turn faster. In fact Penny-farthing#Operation specifically says that it "left no chance of stopping", which is directly contradictory to being launched feet-first on a sudden stop. Mitch Ames (talk) 08:37, 3 February 2010 (UTC)

Here's a try in many words, maybe this will help lead to a clear explanation. See also the linked-to page on penny-farthing cycles which explains this, the explanation probably belongs there. The rider's weight is high and nearly over the front axle, making the bicycle prone to tip over forward, throwing the rider head-first to the ground; a "header". This is exaggerated by braking, but also happens in dips and when striking rocks, etc. In response, riders were in the habit of removing their feet from the pedals and putting them over the handlebars, so when the bike tipped forward, the rider was thrown feet-first instead of head-first. However, with the feet off the pedals, there was no braking using the feet, and a mechanical brake became necessary. —Preceding unsigned comment added by Pardo (talk • contribs) 21:54, 3 February 2010 (UTC)

OK that makes a bit more sense - the feet over the handlebars was to prevent "headers" cause by events other than braking, but in turn necessitated a different means of braking. Mitch Ames (talk) 00:45, 4 February 2010 (UTC)

Protecting the article?

I ran across an article (wish I could find it again) with a bug on the Talk page that said the article had been set so that only registered? users could change it. With the spelling issues and vandalism, I think this article would benefit from such a treatment. Anyone know how to do it? Dmforcier (talk) 19:01, 23 March 2010 (UTC)

Procedure here. --Old Moonraker (talk) 12:57, 2 April 2010 (UTC)

Rim band brake

Does the odd rim band brake merit any discussion? It is rare, found on Nordic Trak (formerly Yankee) bicycles: http://ustimes.com/Bicycle/ —Preceding unsigned comment added by 71.57.231.68 (talk) 04:19, 2 April 2010 (UTC)

That's a great find. Why not include it? We can source it from the Popular Science August 1991 article here. --Old Moonraker (talk) 08:01, 2 April 2010 (UTC)

Done. Thanks for the excellent sources. -AndrewDressel (talk) 14:25, 2 April 2010 (UTC)

Brake load

I reverted an edit eliminating "(up to 75% of the total)." In retrospect that was probably a mistake. This morning it reads a lot less like an estimate, and more like a hard number. I agree with Andrew that it could easily be 100%, although that's far from normal. Perhaps a better statement would be "(up to 100% of the total in extreme situations)". Or just take it out. Opinions? Dmforcier (talk) 14:23, 14 April 2010 (UTC)

Here's a source which suggests 80%, but it's not a technical work and there is no indication of how the figure was derived. --Old Moonraker (talk) 14:34, 14 April 2010 (UTC)

Nice source, but it is difficult for me to see who actually wrote it, and even harder to tell how they arrived at that number. Perhaps a direct quotation is called for. Wilson in Bicycling Science states "The front brake therefore has to provide of 90 percent of the total retarding force at a deceleration of 0.5 g, even if the tire-to-road coefficient of friction is at the high end of the typical range (0.8)." The problem is that the actual number depends on so many factors: available friction, center of mass location, brake lever force, etc. -AndrewDressel (talk) 15:12, 14 April 2010 (UTC)

There is no "actual number" since there are so many variables. Even "90% at -0.5G" assumes a certain mass distribution. I'd phrase it as a range or estimate (e.g. "(up to 90% of the total)"), then add a citation with quote (use the quote= param). (Hmmm. I think we need referenced sources in a new section. Then the quote would be the ref text.)

Btw, this issue suggests a missing section: something along the lines of Brake system dynamics where weight transfer is discussed. (The section(s) in 'The Complete Guide to Public Safety Cycling' is quite good. There probably is such a discussion in the less specialized articles here that we could refer to for the meat.) Then reference that section wherever the issue comes up. Dmforcier (talk) 16:26, 15 April 2010 (UTC)

It is already discussed in Bicycle and motorcycle dynamics, and that discussion is already linked to in the Braking technique section. Perhaps another link would be helpful. -AndrewDressel (talk) 19:23, 15 April 2010 (UTC)

I added the Wilson cite with quote. You're right: it's hard to get a quotable number out of his statement. I could as easily accept 80% (since that's the implied limit of adhesion). Need the page for the citation, please. What do you think? Dmforcier (talk) 17:28, 15 April 2010 (UTC)

Page number added. --Old Moonraker (talk) 17:57, 15 April 2010 (UTC)

Thanks. I reverted your edit to keep the short form reference. Note that if you click on "Bicycle Science" in the note, it will take you to the linked citation. Dmforcier (talk) 17:45, 16 April 2010 (UTC)

It was a actually my edit that was initially reverted. I think the number should either be removed or the weasel words improved. Up to 90% doesn't suggest an estimate, it suggests a limit, which is clearly not accurate. It depends on far too many variables, most of which are dynamic. Stoppies aren't unusual, and when your back tire's off the ground, 100% of the braking is on the front. Perhaps an allusion to the cause would be appropriate, such as: "...because weight transfer during braking allows more traction for braking on the front wheel." Even estimating a number seems pointless, as it can vary to such extremes.Nwimpney (talk) 03:50, 1 May 2010 (UTC)

Broken ref

Ref 22 (at the time of writing) doesn't work. My previous repair, to give the standard short form suggested in Wikipedia:Footnotes#Style, was reverted, with the admonition "leave the short form reference". What am I missing here, please? --Old Moonraker (talk) 14:27, 18 April 2010 (UTC)

I guess you didn't read my reply to you on the line above your new section?

Ref 22 worked fine when I tested it and it works fine now. How is it not working for you?

Your edit is a short-form reference (I didn't use the right term in the edit note), but it does not produce a Wikilink to the full citation as mine did (and now does again). See Wikilinks to full references. Why did you change my ref format? Did you not understand how it is supposed to work? Dmforcier (talk) 18:48, 19 April 2010 (UTC)

Yes, I do understand how it works, after a long and painful apprenticeship in such featured articles as Charles Darwin and William Shakespeare. Accordingly, I was expecting something like the {{Template:Harvard citation}}: see WP:CITESHORT. I would also expect the title of the work in the footnote to be the same as the title of the work in the "Sources" section. It isn't. When I referenced the correct title and added the page number, I naturally used the method with which I was familiar. --Old Moonraker (talk) 20:27, 19 April 2010 (UTC)

Afterthought: why, actually, is this reference using a different system from all the other 30-odd (at the time of writing)? The work is cited twice (incidentally in two inconsistent formats) whereas the relevant style guide suggests that this should be done only for "frequently cited sources": in our case, Sheldon Brown. For consistency the method should be applied to Brown's work: all the rest should be in the footnotes only. --Old Moonraker (talk) 21:21, 19 April 2010 (UTC)

Oops. Got the title wrong. Thanks for pointing it out.

Re the different systems, there's always a f*g Catch-22, isn't there? Introduce a feature and someone complains about it. Don't you have anything better to do? The second ref is inconsistent because I haven't found it yet! Think you might be constructive and say where it is? <<grrr>>

The reason I started using a centralized citation style is I'm hoping to combine and standardize all the many references to the same sources, especially Sheldon's Glossary. The solution is not straightforward in that the Glossary has sub-pages and I don't want to cite each separately. Now I have a way to do it (re: Template:cite web Discussion page). Essentially you use a {{harvnb}} with the |p= param as a link (or {{sfn}} in much the same way). I just haven't got around to doing it yet. It will be a big job, and you're welcome to help.

You still haven't said why you think ref 22 is broken. Dmforcier (talk) 01:46, 20 April 2010 (UTC)

Re: "Don't you have anything better to do?" Don't forget that you asked someone to complete this. My answer, though, is "yes I do", on several more significant articles, in preference to fiddling around here. I was going to harmonize all of these refs to the same style but left it alone for fear of upsetting other editors' seeming preference for non-standard formats. Now I see that you are going to give it a try: good. --Old Moonraker (talk) 05:50, 20 April 2010 (UTC)

That didn't refer to your contributions (for which I thanked you), but to your denigrating mine. Can we declare this pissing contest over now? Dmforcier (talk) 17:44, 21 April 2010 (UTC)

Finished converting footnotes to {{harvnb}}. I suppose it was worth it... Dmforcier (talk) 17:36, 22 June 2010 (UTC)

Larger rotors equals Greater stopping power ?

In the 'Disc sizes' section the following statement appears: "Larger rotors provide greater stopping power by virtue of a longer moment arm for the calliper to act on." This seems to be causing some dispute. IMO, a {{cn}} flag is proper as the statement is doubtful and not, as some have claimed, "basic physics".

The basic physics are these: For the same torque, less pad pressure is needed with the larger rotor (and its correspondingly longer moment arm). That does not necessarily equate to "greater stopping power"! First, stopping power is usually limited by adhesion. All systems that can reach that limit have the same "stopping power". Second, potentially greater - possibly unusable - torque can be traded for throw, effort, or modulation. This is engineering, not physics.

Unless this is clarified, I'm in favor of deleting the statement. Dmforcier (talk) 15:10, 25 May 2010 (UTC)

Trading a smaller rotor for a larger will result in an increased resistance to the rotation of the wheel for the same application of clamping force. Obviously, if one begins to tinker with other variables a the same time, simply enlarging the diameter of the rotor may not change anything, because one is not simply enlarging the rotor diameter. It is clearly implicit in the article as written that all else is assumed to be equal. Perhaps that needs to be stated explicitly, or perhaps the phrase "stopping power" should be exchanged for a more specific term; but a {{cn}} is not the most graceful solution when a sufficient application of Newtonian physics alone will provide the correct answer, and removing the statement entirely is excessive, as it may not be readily obvious to some that this is the case.

Further, when you state that "stopping power is usually limited by adhesion," remember that the limit of adhesion is not a fixed value and will change with surface condition, tire pressure, weight of the rider, load transfer under braking, lateral loading during turns, tire contact patch distortion, and a variety of other factors. Saying that "all systems that can reach [the limit of adhesion] have the same 'stopping power'" makes the naive assumption that there will never be a higher limit of adhesion. Particularly in the case of bicycles, this is ridiculous; even motorcycles, much heavier machines with a MUCH lower center of gravity (and thus a lower percentage of forward weight transfer under braking), will on dry asphalt lift the rear wheel before the front tire even begins to approach the limit of adhesion; and especially with their far higher centers of gravity, I have yet to find the bicycle that will lock and slide the front tire before doing the same. In any case, as stopping power cannot usefully be defined in relation to a constantly changing limit of adhesion, as this assumes the limit of adhesion to be a fixed value, it is best defined as resistance to rotation. After all, this is engineering. There are physics involved.

Lastly, the placement of this phrase in a clearly labeled discussion about disc sizes renders consideration of other factors in the same section moot. Just because discussion of the problem can be made more complex does not mean it should be; in context, a section about disc size with no discussion about the effect of varying disc sizes in isolation would be a severely lacking section.

I have (again) removed the tagging here, now with added wording to make explicit the implication that disc size and its primary effects are being considered in isolation. Greater clarity here should remove the source of the problem altogether. web user 11:19, 23 June 2010 (UTC)

I reverted the edit. The "All else being equal" phrase helps, but by itself isn't enough. And removing the pointer tag to an ongoing discussion is bad form. (If there's an alternative to {{dubious}} you're welcome to use it.) BTW, there's been a {{cn}} tag on this for quite a while. Surely there's a more in-depth discussion of the topic somewhere?

Perhaps the problem is more with the phrase "stopping power". As noted above, increased counter-torque does not necessarily yield a shorter stop. In fact, if it induces a skid the stop may be longer (the phenomenon is the justification for ABS on cars). If the phrase "stopping power" or "braking power" is used, there must be some note that it might make no practical difference. If that makes the discussion more complex, so be it. It's not like we're short on space here.

But there may be a bigger problem with the 'Disc brakes' section that you've crystallized with your rather specious argument about "complicating a section". No other section here isolates one factor in an engineered system. IMO it is improper to do so since it makes it all too easy to ignore the interaction between factors in such a system. For instance, larger radius means a longer bending moment arm on the fork blade. and, unless the chord length remain similar by the addition of support arms (i.e. even more weight), increased lateral flex - a potentially fatal problem. On the upside, increased radius can allow lighter hydraulics since less clamping force (with lower internal pressure) is required. But then the claim of "better stopping power" would be bogus. Perhaps the other 'component' sections are likewise flawed?

There's an good argument to avoiding all this engineering argle-bargle here. The way to avoid it is avoid making statements that require qualification. Perhaps a better approach would be to note in a paragraph within a non-component section the move to larger rotors as a trend. Dmforcier (talk) 20:49, 27 June 2010 (UTC)

I have replaced the term "stopping power" with "braking force" in an effort to avoid bringing things like tire adhesion into the scope of the claim. There is nothing dubious about the effect of rotor diameter, it is in fact basic physics, and it is a well-understood fact of life for anyone who has experimented with different rotors on their bike. Per the recommendation above, I have left the dubious tag in place, though it pains me to do so. 207.118.89.78 (talk) 03:15, 25 September 2010 (UTC)

The statement in question, "Larger rotors provide greater braking force for a given pad pressure, by virtue of a longer moment arm for the caliper to act on" is factual and easy to demonstrate: FrictionForce = uN, where u is the coefficient of friction and N is the normal force, which would be directly proportional to pad pressure, a given constant in this case. Therefore, the (friction) force on the disk from the pad is constant, as well, as the coefficient of friction does not change in this scenario. The other formula is this: torque = Fd. Torque equals force times distance. Since the force is constant, the torque on the hub (via the disc) is directly proportional to the distance (length from the center of the hub to the brake pad), which is directly related to the diameter of the rotor. The assumptions here are the wheel is moving in both instances (i.e. not locked-up). This is easy enough to visualize for anyone who's used a ratchet or wrench to remove a bolt. The longer the wrench / ratchet, the more torque is applied to the bolt for the same force applied on the end of the wrench. I think "Dmforcier" tries to distort this with references to "adhesion" and such, but I think it's fair to assume the wheel is spinning, has non-slipping contact with the ground, and the differences in the length of the rotor will keep these conditions constant. In other words, I think it is fair to assume the statement refers to “normal riding conditions”. In that case, the larger rotor will have a greater braking (and stopping) force as shown by the above formulas. Sure, the larger rotor might lock the wheel easier under some conditions, but that is beyond the scope of the sentence. Continuing to keep the dispute of this statement in place will likely just confuse those without physics backgrounds. The principle is sound: larger rotors stop the bike easier (i.e. take less finger pressure). —Preceding unsigned comment added by 174.21.143.81 (talk) 03:46, 10 December 2010 (UTC)

What gets my goat is that some people in this discussion page would rather dispute all sorts of statements that are true under normal conditions, yet this article doesn't go in to any depth about what the differences in the disc standards are, which is why I came to the page in the first place. It seems to me if just a fraction of the energy put in to disputing things these users (one in particular) was used to contribute to the article itself, the article would be vastly improved. It seems that Dmforcier wants to argue about engineering trade-offs, and not general principles, yet later he says that engineering “argle-bargle” should be avoided. Arguing against statements because "The way to avoid it is avoid making statements that require qualification" just leads to shorter articles that have less useful information. Just as there are different educational levels of physics and engineering, there can be different levels of bicycle brake education, as well. Choosing to omit statements from the article for fear of making a statement that can be disproved under specific conditions or without naming all the engineering trade-offs behind them tends to omit the basic level of potential education the article could have. If the goal is to educate people, it may make more sense to write to their level, and something they can understand, rather than write to appease people who already know all the engineering trade-offs and exceptions. Here's another example of useless bickering by Dmforcier: ""Disc brakes are able to operate at a higher mechanical advantage than rim brakes because disc rotors in good condition are more true than rims in good condition, and thus do not need to retract as far from the rim when released" That sentence is a mis-statemant (sic). Pads run closer to the disc because they have to." Last I checked, disc brake pads don't "have" to do anything, Dmforcier. This is just another engineering trade-off. Either the pads travel further such as they do on a rim brake, where the rim is subject to bending during cornering and tends to get much more out-of-true than a disc, or you have the pads close to a disc. Since the pads of the disc do not need to be retracted as far, the mechanical advantage of the levers can be designed to incorporate less travel and more pressure for a disc brake caliper. Although the rim is effectively a giant disc and therefore could potentially have more stopping power than the disc, the pads must be retracted far enough in practice that the mechanical advantage of the levers is reduced and these gains are not seen. The ideal situation is to have the pads as close as practically possible to the braking surface such that the brake lever travel can be used to create force instead of pad displacement. But again, Dmforcier, you could nit-pick specific sentences with exceptions until the article is so concerned with only containing absolutely true statements that it has no educational information and is only four sentences long, or you could ask "which are more effective?" It doesn't take much observation to see that discs are preferred by professional downhill racers and riders who can ride solely on their front wheel for extended distances, and, generally, race cars and big trucks have much bigger discs than common cars. Racing motorcycles generally have bigger rotors than cruiser motorcycles. And bigger discs do provide more stopping power (regardless of whether it can all be utilized). Therefore, the statements you dispute are generally true, in general situations, for a general audience. —Preceding unsigned comment added by 174.21.143.81 (talk) 04:53, 10 December 2010 (UTC)

I've asked repeatedly for a citation or in-article rationale for the statement. When you get around to actually contributing to the article instead of sniping, try your hand at providing one. Dmforcier (talk) 19:36, 22 November 2011 (UTC)

Whilst I agree that basic Newtonian physics says a larger disc will result in a larger retarding torque there are other complicating factors. A larger disc will have a higher surface speed than a smaller disc, since the coefficient of friction varies (falls) with speed, doubling the size of a rotor will not double stopping power. In addition, the higher speed will lead to increase in heat generation (after all if we have ‘better braking’ we are converting the same amount of kinetic energy into heat in a shorter period), although this may be offset by the larger surface area of the disc. None of this undermines main point of the article though and for practical purposes I believe it is fair to say that a larger disc does result in improved braking power.

Note that I use the phrase ‘braking power’; I feel this is a valid phrase since in engineering power is defined as ‘work done divided by time’. In the case of a larger disc brake that stops a bike more quickly, the same amount of work is done but in a shorter time period. 138.38.72.19 (talk) 16:29, 5 January 2012 (UTC)

No. The argument that one arrangement generates more heat that another is fundamentally flawed: the same amount of work must be done to cause the same change in speed of the same mass. This is simple conservation of energy - different brakes can't simply cause that energy to disappear. Whether th energy is converted to heat at low power over a long time, high power over a shorter time, or the same power via a difference in applied force doesn't alter that. If you want to keep temperatures down to a minimum that is actually an argument in favour of larger discs: the increased thermal mass does not heat up to the same extent for a given amount of work, and the increase in surface area makes it a more efficient radiator to dissipate that heat more quickly. Unless there is some more convincing argument that someone wants to present I'm tempted simply to remove the dubious tag since it appears without foundation. You can argue it needs a cite, but there's nothing dubious about it. Crispmuncher (talk) 15:01, 23 July 2012 (UTC)

New Actuation mechanism section

Attendant to moving the discussion of the potential problems with Bowden cables to that article, I noticed that there were several duplications of discussion of the types of actuation mechanism, notably cables and hydraulics. The actuation mechanism is generally independent of the type of brake; both types of rim and disc brake exist. So I combined the discussions in to a new section enclosing the Brake levers section.

One question: does the new section need to be closer to the top? Or is it okay where it is? Dmforcier (talk) 20:29, 15 June 2010 (UTC)

Ad/Dis - a question of style

Andrew has been agglomerating come of my one sentence paragraphs (some of which I completely agree with, btw), particularly in the Advantages/Disadvantages sections. This brings up a question of style. In those sections I use a paragraph to treat a single Advantage (or Dis). That often leaves single-sentence paragraphs, but it seems to me that it makes the section clearer. Andrew seems to want to group the points by component, so several points can appear in the same paragraph. To me this looks prettier on the page but is less clear and harder to gloss. Discussion? Dmforcier (talk) 18:06, 19 June 2010 (UTC)

See Wikipedia:Paragraph#Paragraphs: "One-sentence paragraphs are unusually emphatic, and should be used sparingly." "Some paragraphs are really tables or lists in disguise. They should be rewritten as prose or converted to unmasked form." I'm all for bulleted lists. -AndrewDressel (talk) 21:27, 19 June 2010 (UTC)

Yeah, that's really the issue. I didn't want to go there (bullets), so let's leave it as it is, unless there's a popular movement in one direction or the other. Dmforcier (talk) 18:46, 20 June 2010 (UTC)

What the heck is this?

And how does it work?

http://www.vintagebicyclepress.com/images/Schulzbrake.jpg

Answer: http://www.bikequarterly.com/images/SchulzBrakeSolution.pdf
:Dmforcier (talk) 19:32, 22 November 2011 (UTC)

Hydraulic vs Mechanical

The article currently states that "modern hydraulic disc brakes generate more stopping power than mechanically actuated disc brakes." Why would this be true? Both transmit displacement and force while usually converting the former into the later. Both have frictional losses. A citation has been requested for more than a year. Unless a reliable source can be found, this claim should be removed. -AndrewDressel (talk) 00:05, 11 November 2011 (UTC)

Okay. Out it comes. -AndrewDressel (talk) 16:37, 16 November 2011 (UTC)

Dubious statement

In Braking Techniques, this: As the front wheel does not skid,
I've skidded the front, though to be fair it rarely happens on a good surface. So what's the best way to fix this? (Btw, I'm not in favor of advocating front-wheel-only braking at all. So should the whole paragraph go?) - Dmforcier (talk) 19:27, 22 November 2011 (UTC)

On the one hand, talking about braking technique at all is heading down the slippery slope towards how to, but on the other hand, load transfer is a real phenomenon that occurs whenever bicycle brakes are used. Perhaps it is sufficient to insert on clean, dry pavement. -AndrewDressel (talk) 19:44, 22 November 2011 (UTC)

Btw, Sheldon Brown says "skilled cyclists use the front brake alone probably 95% of the time, but there are instances when the rear brake is preferred."

Load transfer makes it harder - not impossible - to skid the front. Dmforcier (talk) 20:05, 25 November 2011 (UTC)

I believe that on a standard upright bicycle with rubber tires on clean, dry pavement, where the coefficient of friction is close to 1.0, it really is impossible to skid the front wheel. Instead, load transfer increases friction enough to create a moment about the center of mass that flips the bike and rider over the front wheel contact patch before skidding can occur. Although I can't find where he explicitly says so, Sheldon Brown appears to agree in statements such as these:

• "Maximum braking occurs when the front brake is applied so hard that the rear wheel is just about to lift off. At that point, the slightest amount of rear brake will cause the rear wheel to skid." (Notice no mention of front wheel skidding or the danger of it.)
• "Long or low bicycles, such as tandems and long-wheelbase recumbents, have their front braking limited by the possibility of skidding the front wheel, since their geometry prevents lifting the rear wheel." (Notice the distinction that it is only long or low bicycles that have the possibility of skidding the front wheel.)

John Allen, to which Sheldon provides a link, is more direct:

• "This is your braking technique for straight-ahead stops on clean, dry pavement. Under these conditions the front wheel will never skid, so you can adjust the front brake to keep the bike under control."

You make a good point: this is dangerously close to "How To". But I'm not yet moved to strike the whole section (might become so, though). However, the more I think about it the less I like the "front brake only" thing. Seems to me that under heavy braking it even decreases stability, as the back end wants to come around. If you want to keep the section, how about replacing with "since the front wheel is less likely to skid"? Dmforcier (talk) 20:05, 25 November 2011 (UTC)

Both authors suggest that the best way to prevent the rear wheel from coming around is to apply less force to the rear brake. It is only when the rear wheel is skidding that there is danger of it coming around. Sheldon says "Using both brakes together can cause "fishtailing." If the rear wheel skids while braking force is also being applied to the front, the rear of the bike will tend to swing past the front, since the front is applying a greater decelerating force than the rear. Once the rear tire starts to skid, it can move sideways as easily as forward."

So, after all that, I am inclined to think that simply inserting the qualifying on clean, dry pavement is the most efficient solution. -AndrewDressel (talk) 00:49, 26 November 2011 (UTC)

Thank you for the references. I understand why you believe that your proposed edit will correct the problem. I disagree. If the challenged, unmodified statement is not true in all situations, then it is not valid as a rationale for the technique. A 'braking technique' is a habit. This habit (front-only) can get the rider in trouble in other situations, i.e. those that are not straight-ahead, clean, dry, etc. Thus while I initially challenged the rationale, I now believe that "fixing" the rationale doesn't fix the actual problem.

A note, btw. The second quote is in my favor: the front WILL skid. A geometry more resistant to flipping is more likely to skid, true, but single-rider geometries also have length and a degree of flip resistance - they too can skid. Dmforcier (talk) 18:11, 26 November 2011 (UTC)

NEVER MIND. In re-reading the offending section, I was much less offended than the first time I read it. The "never skid" statement isn't as unqualified as I initially read it to be. And IMO the section can stand as it is (though I might come up with a tweak or two). Dmforcier (talk) 18:17, 26 November 2011 (UTC)

Well, maybe not "Never Mind" entirely. What's with the "does not cause rapid tyre wear" statement? Since when does split braking cause rapid type wear? Or is it refuting an unstated objection that front-only will "cause rapid tyre wear"? (If so, bad form. Either make the objection explicit or lose its refutation.) Dmforcier (talk) 18:27, 26 November 2011 (UTC)

rod brake image

The image associated with the rod brake seems to have Bowden cables, even thought 1st sentence of the existing section specifically says that the rod brake doesn't use Bowden cables. -— Preceding unsigned comment added by Erkyturkey (talk • contribs) 23:01, 29 July 2012 (UTC)

The Bowden cable in the picture is not connected to the brake. Instead, it passes behind the rods and is probably for shifting. -AndrewDressel (talk) 14:19, 30 July 2012 (UTC)

Perhaps it should be written to express that the defining element of the rod brake is the rod-like tube that's pressed against the rim, not the means of transferring that braking force from the hand to the wheel? -— Preceding unsigned comment added by Erkyturkey (talk • contribs) 23:01, 29 July 2012 (UTC)

I am not familiar with a brake that presses a "rod-like tube" against the rim. Do you have a picture? -AndrewDressel (talk) 14:19, 30 July 2012 (UTC)

Coaster brakes and uneven tyre wear

I recently became aware that, allegedly, it's common for bikes with coaster brakes to have uneven tyre wear. This came up when my daughter's rear tyre wore completely through. On inspection, it had a few severely worn patches evenly spaced around it. The guy at the repair shop explained this by observing that when coaster braking, the pedals are usually more-or-less horizontal, and this corresponds to only one of a few positions for the rear wheel. (This wouldn't be true if the front and rear chain rings had a relatively prime number of teeth, but this appears not to be how it's done.) Anyway, combine this with the common tendency to skid the rear wheel, and uneven wear ensues.

I found this to be interesting, useful, and non-obvious. However I'm not sufficiently expert in the art to want to insert it into the article on my own authority. I leave this here as a suggestion for others to review and possibly incorporate. -Jgs42 (talk) 23:37, 4 October 2012 (UTC)

It sounds more like the problem is that skidding when braking wears out tires, and the article already states "As coaster brakes are only made for rear wheels, they have the disadvantage common to all rear brakes of skidding the wheel easily." -AndrewDressel (talk) 13:02, 5 October 2012 (UTC)

Drum brake

A long section about drum brakes was deleted. I wonder why. Nikolas Ojala (talk) 16:28, 11 March 2014 (UTC)

Brake disks are fitted back-to-front : why ?

Google Images [ bicycle disk brakes ] shows many brake disks that have spokes. The spokes are slanted or spiral, not radial. From an engineering viewpoint, the disks should be the other way round. The spokes are in compression, not under tension. Yes, Jobst Brandt said wheel spokes push, not pull, but he is not a reliable source. Is there a reason, or is it just fashion ? I'm expecting a brilliant response along the lines of the left-hand thread on a left pedal argument ...

Yes, I'm off-topic, but Google finds no answers, and I was sure Wikipedians would have the answer. It's probably not notable enough to add to the article, though !

--195.137.93.171 (talk) 10:28, 16 April 2014 (UTC)

Brake discs cannot "have spokes". They mount to the hub completely independent of any wheel mounting system. Otherwise you couldn't get a caliper around the edge of the disk.

What happens when you put a spoke into compression? It buckles. Spokes are in tension, not compression.

No, there is nothing here that merits adding to the article. Ask questions in BikeForums.net Mechanics forum, not here. Dmforcier (talk) 16:05, 24 April 2014 (UTC)

Take a look at the picture of a bicycle disk brake provided in the existing article to see what he means. The disk has so much material removed that what remains looks like spokes.

Compression spokes have been in use with great success for thousands of years. Tension spokes are a relatively new invention. Mavic even tried carbon fiber compression spokes in their ill-fated R-Sys wheels.

If there is a good explanation for why the "spokes" in brake disks appears to be designed to be in compression instead of tension during braking, I would sure like to know it. If the orientation is merely for aesthetics, and the compression doesn't matter, that would also be interesting. Either way, it deserves a mention, if reliably sourced. -AndrewDressel (talk) 17:06, 24 April 2014 (UTC)

Yes, historical spokes (e.g. wooden wheel spokes) are compression spokes. I was talking about bicycle wire spokes, which are a different animal. One could consider disk "spokes" to be in compression, in which case they would be oriented to oppose the force vector, which is anti-rotational. Dmforcier (talk) 17:29, 13 August 2014 (UTC)

Kinetic vs Mechanical Energy

In several places, this article refers to the brakes as converting kinetic energy into thermal energy. Yes, often they convert kinetic energy when slowing the bike. But they also convert potential energy when limiting speed while descending without necessarily slowing the bike. Wouldn't it be more accurate and more general to say the brakes convert "mechanical energy to thermal energy"? JDHeinzmann (talk) 14:52, 5 May 2015 (UTC)

Brakes also can hold the bike stationary. Then they're not converting anything; they're maintaining stasis. --Dennis Bratland (talk) 17:51, 16 May 2015 (UTC)

The best way to state this is to say that a brake resists motion. Exactly how it does it depends on the workings of the brake. Not all brakes dissipate kinetic energy as heat.

38.69.12.5 (talk) 03:13, 30 October 2016 (UTC)

Coaster Brake Inventor

Another WP article states that William Robinson invented the bicycle coaster brake, not Willard M. Farrow. However, a 1947 publication of Cycling Handbook produced by the League of American Wheelmen asserts on page 21 that the inventor of the coaster brake was Alvin J. Musselman. I'm inclined to think that these men all developed different versions of the coaster brake. Of the three, Robinson seems more likely to be the one to have invented the first coaster brake, due to his extensive activities in safety-related fields. That said, definitive information seems to be elusive.

38.69.12.5 (talk) 03:10, 30 October 2016 (UTC)

Please register so that we know who we're talking to.

The contents of your edit are not in question, though they should be cited. The issue is that this is not the place for controversies about who invented what. The article is about brakes, not about inventors. If there is an undisputed inventor, then he can be referenced. Otherwise the appropriate thing to do with the controversy is to put it in a footnote, not a new section. Dmforcier (talk) 01:04, 2 November 2016 (UTC)

Is helpful for someone to point out that this article contradicts another article. I would say that the biggest problem with this article is that it obsessively details every mechanical fact about bicycle brakes as if this were an engineering textbook, and gives too little attention to non-mechanical topics like history. An improvement would be to shift much of this excess detail about brake mechanics to sub-articles, especially the more obscure and obsolete brake types, and expand the content about wider topics. Why does the history section start at 1817 and stop at 1898? We need to cover everything that happened after that. We say nothing about bicycle brake regulations and laws, like the coaster brake requirement on US children's bikes, and the wider implications of that law. The braking technique section is a thinly disguised how-to, and needs to be pared back a lot.

Anyway, the article is a trainwreck. Correcting the fact of who invented the coaster brake is one small step toward improving it. --Dennis Bratland (talk) 01:53, 2 November 2016 (UTC)

I won't say that you're wrong. Some of use have been standing athwart the tsunami of "common wisdom" shouting "Stop!". I will say that there is a limit about what can be contained in an article. For instance, if someone wanted to create an article about coaster brakes, then go for it. If you have an outline of how this article could be decomposed, several of us, at least, will be glad to entertain it. Dmforcier (talk)

Electric regenerative brake in e-bikes?

Electric cars make good use of regenerative brakes, electric bicycles apparently not so much, even when fitted with a hub motor. Would be really helpful for riders in hilly areas with high brake wear. --2003:C6:3738:2C5D:79B1:D58E:AEEA:DBF6 (talk) 00:35, 17 February 2022 (UTC)

Brake sides

I've recently needed to know which is the standard brake side for 2-3 countries, and there does not appear to be a good global source. I'd like to add a table to note the standard country by country of left=front vs left=right. Would this be best placed on this page, or in a linked separate table only page? — Preceding unsigned comment added by 2406:E003:E15:F001:10EE:9464:C019:7661 (talk) 06:27, 21 April 2022 (UTC)