Cantilever brakes

Hi I am having a look for a road-type bicycle with which I can do some commuting as well and I am checking some cyclocross bikes.
Most of these bikes are equiped with cantilever brakes which dont seem to be very reliable...
Do you think these brakes are very bad in rainy and mud conditions? Do you think that I can replace those with a v-brake system or a road bike brake system? Are the fittings the same?
Thanks. /img/vbsmilies/smilies/smile.gif

 

Cyclocross is all about mud and rain, and that's what cantilevers were designed for.

Cantilever brakes are reliable provided they are correctly set up and maintained.

It may be possible to replace the cantilevers with regular V-brakes, but they will not work with road levers. You will have to use a "travel agent" in the cable if you want to keep the levers. With the extra cable complication I can't see how this can be any better than cantis.

It will also be impossible to fit a normal caliper brake as it will not reach far enough from the crown or brake bridge to the rim. The crown/bridge may also not even have a hole for mounting the brake anyway.

In short, if you're interested in a 'cross bike, don't be put off by the brakes.

 

+1 on the gist of the message above. Cantilever brakes are plenty reliable and offer the best balance between stopping power and mud clearance which is why they're the most typical brake in cyclocross racing. But there are cross specific V brakes designed to work with the pull ratios of normal road brake levers and integrated brake/shifters like these: http://www.pricepoint.com/detail/20901-040_TRPC90-3-Parts-843-Cyclocross/TRP-CX9-Ti-Mini-Cross-V-Brake.htm

You'll get additional braking power and less brake chatter with full carbon forks but lose some mud clearance if you go to V brakes for your cross bike but if it's really a concern (it shouldn't be) then there are cyclocross specific V brakes you can buy.

-Dave

 

My commuter bike uses ordinary 105 STI levers and ordinary V-brakes with no "Travel Agent" or equivalent. I have used this combination in rain or shine for 5 years. This combination, almost universally said to be unworkable, is actually perfectly workable. With SwissStop green or XT pads on Mavic rims,the brakes are more powerful than any other rim brake I have tried, including Magura hydraulics.

I would make a big proviso on this claim, and say that you have to be motivated to keep your rims just about absolutely true on a regular basis, and that you have to shorten your brake cables, to make up for pad wear, frequently. In addition, it can be a bit hard to unclip the v-brake noodle to get the wheel off, so I always travel with a hex key to loosen the cable clamp bolt. Because the pads always sit close to the rim, the mud clearance probably wouldn't be too good.

 

Oy! I'm glad that you finally added the proviso which you omitted in the past when describing your V-brake setup ...

• As I mentioned in the now-distant-past, I found that you can use a standard V-brake on the rear because the "stretch" in the cable provides some pseudo-modulation ...
• As noted, due to the limited gap between the brake surface & the brake pads, the rim has to be true!

A mini V-brake can be used with standard Road brake levers ...

Tektro also has one V-brake whose appearance (length) looks closer to a standard V-brake (to me) than a mini V-brake, but it uses a standard Road brake lever, so it must be shorter than a standard V-brake!?!

Unless the frame's head tube is very long, as others have noted, then cantilever brakes are generally more-than-fine if they are set up properly AND the headset is properly adjusted AND rider does not put all of his-or-her weight on the front wheel when stopping ...

In the worst case scenario (i.e., supposedly a longer head tube), you can apparently induce chatter in the front fork under heavy braking with cantilever brakes (presumably) because of the flimsy gauge cable used for the straddle cable whereby some unintended modulation occurs if the cable stretches by otherwise imperceptable amounts OR some other (!?!) reason(s) ...

• If the chatter is due to the straddle cable, then I reckon that the chatter can possibly be mitigated by simply installing a heavier straddle cable [i.e., use a straddle cable cut from a brake cable].

 

(front) brake chatter = vibration when braking ?
if yes, is it harmful for your fork and/or frame ? could it lead to fork/frame failure ?

 

Front brake chatter is entirely down to stiffness (or lack thereof) in the fork steerer tube. Lennard Zinn has given a good explanation of the source of this.

http://velonews.competitor.com/2010/09/cyclocross/technical-qa-with-lennard-zinn-return-to-cross_101807

Basically when you brake the fork begins to flex slightly under the bike. If the front cable stop is at the top of the headtube, this flex pulls tighter on the brake cable, in turn pulling the brake on harder and causing the fork to flex under more. Eventually the brake is pulled on so hard that the friction point between pad and rim is what gives out causing the bike to lurch as the flex suddenly unwinds and the brake releases a bit. The process then starts again. This oscillating flexing and unwinding pulses the front brake giving you chatter.

If the steerer is stiff enough this flexing oscillation is either reduced or non-existent and (in general) it is less of a problem for smaller bikes (where the steerer - and brake cable - is necesarily short). So there are bikes for which this doesn't happen. If it does happen, the simplest cure is to move the front cable stop down to the fork crown (as long as you have a fork with a bolt hole in the crown). Then the cable stop will move with the flex keeping cable tension constant. Most other "cures" rely on defeating the problem by making the brake less powerful (with slack or over-long straddle cables).

I doubt it is a serious structural problem since the flex which causes it is present in all forks on all bikes to some degree. The only reason it is noticeable on a cross bike is due to the long unstopped section of front brake cable. The flex doesn't need to be much to cause it.

Lennard's personal cure is to use a front Vee-brake so that the outer can be run all the way to the brake, again eliminating the effect of flex on cable tension. To run the Vee he uses a special compatible left lever and therefore does without front shifting.

Alfeng is correct in saying there are smaller Vees for road levers. But it seems to me that they may provide less clearance than cantis (with the low cable). Perhaps someone can verify this.

 

I've used V-s with regular levers too.
For the front I rather like the setup, although getting the wheel out can require an additional step. The supposed lack of modulation has never bothered me. People are obviously able to ride in both rainy and dry conditions, on everything from SS rims through alloy rims to ceramic(coated) rims, on old and dry brake pads to spanking new Salmons, all of which has far greater influence on brake behaviour than V-brake+ regular levers.
For the rear I haven't been as succesful. The longer cabling run means there's more room for slack, so the sweet spot between clearance and full engagement w/o bottoming out becomes a lot smaller.
I'd like to try it using Nokon cabling sometime. It's suppose to be less compressible than the other stuff out there.

 

Nor me. I'm never quite sure what people are talking about when they use the term "modulation" to descibe why certain systems allegedly will work, and others allegedly won't. I'm not sure that the word describes a relevant commodity.

 

I can see what they're getting at, but I fail to see the specific importance for a long-pull/short pull mix up. The brake response(or whatever you want to call it - what happens between squeezing the lever and slowing the bike down) is always different from bike to bike anyhow, and anyone who fail to realize this is in for a world of hurt and fear when they transition from one bike to another, or even face a large change of weather during a ride anyhow. A brake mix is just another contributor, and not a very important one at that.

But then there are always the people who pushed for the invention of the "brake modulator", that special, spring-loaded, compressable V-brake noodle intended to prevent people from OTB-ing by V-brakes. Naturally hybrid systems like long/short would scare their pants off.

 

Maybe this will help: http://sheldonbrown.com/rim-brakes.html#ma

Braking systems are just that, 'systems' and matching the components from both ends of that system delivers the best performance. You can certainly mismatch pieces and in general get away with it, especially with cantilever brakes where you can vary the brake's mechanical advantage quite a bit by changing the length of the straddle cable. But mismatching brake levers to brake characteristics still represents a poorly designed mechanical system which may not be important to you if you don't ride in the rain or ever ride with rims that take a ding and wobble a bit or worry about mud clearance as cyclocross riders do but it's still a suboptimal solution.

Braking modulation isn't just a marketing term, if you ever are unfortunate enough to ride a bike with poor modulation characteristics (often poorly setup cantilevers with poorly chosen levers) and lock up the wheels when you're trying to feather the brakes then you'll appreciate what good braking modulation can do for a bike.

-Dave

 

I have a Cannondale CX 9 frame that I have fallen in love for training and commuting. But the only thing I will mention is that I put a pair of Avid Shorty brakes on it that are fine in most conditions but I also added a rack and panniers for the bike if I want to do some hotel touring. I would not trust the braking power on them on a fast downhill with the panniers fill on them. I guess that is why they have touring bikes.

In a strange way got me used to do less braking when training which is a nice trade off. Recently they made terrible noise and my LBS said it is cause of the humdity and use some rubbing alcohol on the rims. It did eventually work.

-js

 

Sure there are performance/feel differences between brake setups. There are plenty of factors that influence braking, and lever/brake mismatch is just another contributor. Maybe it's worse than some, but it's certainly better than some others.
IMO, you can't say "don't ride a mismatched system" unless you also say:
- "don't ride dried-out pads",
- "don't ride a rim-braked bike with SS rims",
- "don't ride in the wet",
- "don't ride with dusty rims",
- "don't transition between hydraulic discs and any kind of rim braking"

As far as I'm concerned, the change in brake response that occurs between initial braking and rim being swept dry when riding in the rain has a far greater influence than mismatched levers/brakes. But even that one is completely dwarfed by the change in going from rim to (hydraulic) discs.
There are far bigger changes to be had within otherwise "approved" or maybe "not actively warned against" scenarios, so why single out mismatched brakes/levers as a special danger?

 

That worries me a bit too. I used to have a bike with v-brakes and I remember one day that the bike was not slowing down whilst pulling the brakes on a snowy day so after that I have a bit of a worry about any rim brake. The thing is that I was thinking of a road bike with a bit of touring abilities and these are not usually available with disk brakes. I saw some fitness bikes with disk brakes. I was also thinking of a steel frame since I want to have a bike that I can have for a long time too and I did not find a single carbon steel bike with disk brake fittings around. At the moment I am using a bicycle with drum brakes. These are not very powerful but the wheel does slow down when I use them. If the bike doesnt slow down its just a matter of the road surface and the tires.
I checked these cyclocross bikes mainly because they seem a bit more rugged then standard road bikes since I will be using the bike mainly on road but also in some bad road surfaces possibly sometimes whilst raining. But keeping the rims true and checking the cantilever brakes every once in a while its a bit too much trouble I think. I also tried to repair some cantilever brakes once and they really dont seem to keep straight very easily even if the rim was straight since the two pads are not connected with a stable bridge like linear pull or v-brakes but just a wire that seemed to move about quite easily.

 

Cantis/v-brakes not staying centered is mainly an aestethic issue, as long as one pad isn't dragging. Once there's a little more than token force in the system the power will be equalized between the sides anyhow. The trick to centering them is to tweak the return spring tension. Park tool and Sheldon Brown will tell you how.

All rim brake system will be a tad weak initially in bad weather. It takes a few rotations before the pads have swept the rims clean/dry. But once that's done, even rim brakes should be operational at least.

CX bikes are popular as year-round commuters, due to ability to take wider wheels, and these days, available with disc brakes. They're so-so as touring bikes, as they often have fairly short wheelbases to promote manouverability.

The "don't transition" bit was a comment in relation to the dire warnings about using mismatched brake parts, on account of that upsetting the intended brake response. But IMO the difference between hydraulic discs and any rim braked system is bigger than pretty much all the differences that can be achieved within rim brake systems regardless of setup. And yet using both rim brakes and disc brakes is something a lot of people do regularly, apparently none the worse for it.

 

I use V brakes with Travel Agents and am very happy with them.

I notice that everyone who finds V brakes with regular throw levers (i.e. integrated type) "satisfactory" has major provisos such as the need to keep them within a gnat's a$$ of the rims, the need to keep the rims perfectly true, and the need to fiddle around dismantling the cable when you want to remove the wheels because of the tight clearance required.

I used V brakes w/ conventional throw levers for a few weeks and found all of the above to be true. They indeed worked fine as long as you put up with the above. BUT, I find all of that stuff "unsatisfactory", not "satisfactory", and therefore would not use the V brakes without the Travel Agent.

The TA is cheap, easy to install and works perfectly. I haven't found a downside to them yet in two full years of use. Although the brakes worked "fine" without them, they work much better with them. Why wouldn't you use them? Maybe it's aesthetics? (I can't imagine, but you know bike weenies). Maybe they fail under harsh conditions? (I'm not a mud or sleet and snow rider).

 

Quote: Originally Posted by tafi .

Front brake chatter is entirely down to stiffness (or lack thereof) in the fork steerer tube. Lennard Zinn has given a good explanation of the source of this.

http://velonews.competitor.com/2010/09/cyclocross/technical-qa-with-lennard-zinn-return-to-cross_101807

Basically when you brake the fork begins to flex slightly under the bike. If the front cable stop is at the top of the headtube, this flex pulls tighter on the brake cable, in turn pulling the brake on harder and causing the fork to flex under more. Eventually the brake is pulled on so hard that the friction point between pad and rim is what gives out causing the bike to lurch as the flex suddenly unwinds and the brake releases a bit. The process then starts


FWIW. Lennard Zinn's how-to books are certainly amongst the best ... and, he is a font-of-knowledge ...

• and, of course, I certainly don't ride a larger frame where chatter is a significant problem ...
• regardless, if one thinks about it then one would think that the longer head tube would actually make the steering column MORE stable!

I'm not saying that Zinn is wrong in why he believes that chatter occurs on the CX bikes which he sets up ... but, I have learned to take what he promulgates in his VeloNews columns with a grain-of-salt ...

Regardless, I must point out that the way Zinn appears to set up his CX bike harkens back to the early days of cantilever brakes (i.e., the 80s, AFAIK) where the cable was often fed through a hole in the stem! Instead, of course, Zinn apparently uses a hanger that must (appears to!?!) attach to the stem's face plate ... THAT's got to be even worse than the intermediate pass through which a hole drilled in the stem provided ...

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WTF?!? I could be wrong, but it looks as though the location which Zinn prefers for his cable hanger places an unnecessary, exacerbating "tension" on his cantilevers AND (therefore) the fork by not having the hanger feed the brake cable as close to parallel to the head tube as possible:

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Talk about aggravating a potential weakness in the overall design!

• someone more clever than I am can perform the actual vector calculations if it matters to them ...

I will suggest that Zinn could mitigate the chatter on the CX bikes which he sets up by changing to a brake cable hanger which runs the brake cable closer-to-paralle than the hanger he prefers to use ... AND, as I previously suggested, the chatter induced by "oscillation" can probably be reduced by using a thicker straddle cable ... AND, on Zinn's bike(s), the "oscillation" can be probably be mitigated by shortening the straddle cable, too! Again, WTF is Zinn thinking with his straddle cable setup?!?

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BTW. As I noted, previously, I can live with what I referred to as pseudo-modulation on the rear brake ... From viewing-up-close a handful of bikes set up by one bike shop that is local to me, that shop's Wrenches prefer to set up "regular" Road brake calipers with the pads as close to the rim's braking surface as a V-brake pad needs to be when used with regular Road levers! One guy I know says he likes THAT configuration because he says that he likes to "pulse" the brake levers to stop ... Really?!?

• maybe he had glazed pads on one of his bikes in the past, so the hard clamping of the pads against the rims is reassuring to him!?!

Well, I suppose I don't have a deft enough touch to "pulse" my brakes in order to come to a controlled stop ... And so, I prefer having modulation over the comparatively hard clamping which having the pads mounted to the brake surfaces results in ...

• basically, modulation is the difference between an on-off switch and a rheostat ...
• or, turning a shaft using a knob attached to the shaft vs. turning just the bare shaft ...
• et cetera.

 

That's very much my opinion too. I have used v-brakes with canti/caliper brakes for quite some time, but I've also eventually stopped using them. Keeping the rear brake operational would eventually grow tiresome, and when revising that I'd revise the front as well. The only bike I left in a mixed state had the original cantis at the back, which circumvented the nuisance.

Depending on riding conditions, Travel Agents can pick up a lot of dirt, something to watch for after a mud-slinging MTB ride. But for a bike that stays mainly on road, or get the appropriate post ride care, that's pretty much a non-issue.

 

I simply can't be bothered to buy them and fit them, as I don't feel that I have a problem that requires fixing. I guess I'm not mad keen on the idea of less powerful brakes, as I'm used to the ones I have. For what it's worth, I switch frequently between road sidepulls, the v-brakes, cable discs, hydraulic discs and hydraulic rim brakes, so I'm used to different feedback from different bikes. The only ones I don't much care for are the road sidepulls.