Cantilver Brakes - Clearance and adjustment

[KneesUp]

I have cantilevers on my bitsa bike. They are attached to Weinmann drop bar brake levers from about 1979.

It all works well - the brakes are great, actually - but in order for them to work well the brake blocks need to be very close to the rim, which seems to run counter to the whole point of cantilevers which I always thought was to give more clearance for mud and gruft. If I put the blocks further away from the rim the lever hits the bars before the brakes are fully on.

This means that as well as having no clearance for mud or much leeway if the wheel gets a wobble, it also means that it's hard to get the wheels off because you can't squeeze the arms together enough to get enough slack in the yoke to release it.

It occurs to me that it might be because the levers are designed to work with callipers, but I thought that it was V brakes that needed a different 'pull' and that levers for cantilevers should be fine.

Any advice much appreciated. I want to replace the old Weinmanns at some point because I find aero lever much more comfortable on the tops, but I'd like to get to the bottom of why I have to have them adjusted this way first.

Thanks.

 

[TheDoctor]

Cantis give clearance for mud on the tyres, rather than the rims.

 

[Shut Up Legs]

@KneesUp: I agree, that's one of the main disadvantages with canti brakes (which I have on my tourer/commuter bike). There's no quick release to help you remove the wheel to change you-know-whats . I also prefer to have the brake pads as close to the rims as possible, but then sometimes to change a tube (because of the aforementioned you-know-whats ), I need to use my multitool to partly remove one of the brake pads, which is a nuisance.

 

[raleighnut]

Cantilever and V-brakes require the same lever pull and are interchangeable, Caliper brakes do have a different pull but will work OK-ish what you need are old school levers where the release is on the lever arm itself.

 

[Rickshaw Phil]

Cantilever and V-brakes require the same lever pull and are interchangeable, Caliper brakes do have a different pull but will work OK-ish what you need are old school levers where the release is on the lever arm itself.

That's the wrong way round. Cantilevers use the same pull as calipers but V brakes need V brake compatible levers.

Sheldon Brown explains in this article.

 

[John the Monkey]

Cantilever and V-brakes require the same lever pull and are interchangeable, Caliper brakes do have a different pull but will work OK-ish what you need are old school levers where the release is on the lever arm itself.

I don't think that's the case, Caliper and Canti brake levers are similar, V-brake levers are different, and mixing and matching V brakes/levers with different types of brake/lever is sub-optimal.

Per the post on wheel removal, why not take the wheel out with flat tyre, and pop it back in before reinflation?

 

[Rickshaw Phil]

This means that as well as having no clearance for mud or much leeway if the wheel gets a wobble, it also means that it's hard to get the wheels off because you can't squeeze the arms together enough to get enough slack in the yoke to release it.
.

Are you using the quick release correctly? On the cantilevers I've come across they are designed for one end of the straddle cable to be released rather than the yoke, as shown in these (not very well focused) photos:

This is usually pretty easy with the brake blocks set close to the rim.

 

[raleighnut]

That's the wrong way round. Cantilevers use the same pull as calipers but V brakes need V brake compatible levers.

Sheldon Brown explains in this article.

Ah got it the wrong way round, Bugg*r maybe its because I've always binned sticky out canti's as being horrible but changed to integrated lever/shifters at the same time on all the MTBs I've ever done.

 

[the snail]

This is usually pretty easy with the brake blocks set close to the rim.

It isn't with mine. I've got cross-style top levers on mine with cable adjusters, so I usually loosen the adjusters off to release the cable end. The OP could fit inline cable adjusters, or as above, old style levers with QR.

 

[Rickshaw Phil]

It isn't with mine. I've got cross-style top levers on mine with cable adjusters, so I usually loosen the adjusters off to release the cable end. The OP could fit inline cable adjusters, or as above, old style levers with QR.

Ah, fair enough. I've not used a bike with cross levers so haven't experienced how they change things.

 

[jay clock]

I went from a trad tourer with cantis that had me pooing myself regularly, to a bike with V brakes (Koga Miyata World Traveller) which inspires huge confidence.

 

[KneesUp]

Thanks all. I take my bike in the car quite often, and with my mountain bike (with canti's) it's easy to release the yoke and pop the wheel off. With this bitsa bike there just isn't enough give, so I wondered if I'd missed something. Thinking about it, what I've missed is that the brakes on the MTB are really badly adjusted and hardly work

I'll need a solution though, it's a pain getting the wheel off at the moment. I have cross tops levers to go on @the snail so good to know that works. The old style levers would be good too - the Exage ones on my old road bike had the button. Does anyone still make levers like that? I have bar-end shifters so the brake levers don't need to change gear too.

 

[RecordAceFromNew]

I have cantilevers on my bitsa bike. They are attached to Weinmann drop bar brake levers from about 1979.

It all works well - the brakes are great, actually - but in order for them to work well the brake blocks need to be very close to the rim, which seems to run counter to the whole point of cantilevers which I always thought was to give more clearance for mud and gruft. If I put the blocks further away from the rim the lever hits the bars before the brakes are fully on.

This means that as well as having no clearance for mud or much leeway if the wheel gets a wobble, it also means that it's hard to get the wheels off because you can't squeeze the arms together enough to get enough slack in the yoke to release it.

It occurs to me that it might be because the levers are designed to work with callipers, but I thought that it was V brakes that needed a different 'pull' and that levers for cantilevers should be fine.

Any advice much appreciated. I want to replace the old Weinmanns at some point because I find aero lever much more comfortable on the tops, but I'd like to get to the bottom of why I have to have them adjusted this way first.

Thanks.

I think there are three likely areas that give rise to your dilemma:
1) The cable outer is too compressible, and/or
2) The hanger is flexing too much, and/or
3) The mechanical advantage of the canti is set too high, which is possible if the straddle wire is short / set close to the tyre for a mid/narrow profile canti unit

The issue you seem to have is too much lever pull translating to too little pad movement. For your levers I would expect every 4 cm of pull at the lever would only result in circa 1 cm of cable pull at the point where it exits the lever. If the mechanical advantage of the canti is set high (say 2 or 3 e.g.), and/or a lot of the cable movement is wasted by compression of the cable outer and/or hanger flex, then only a mm or two may remain in terms of pad movement, which will result in your having to set the pads super close to super true wheels, or else your levers will bottom out.

To examine the mechanical advantage of your brake, you can try comparing cable movement where it exits the hanger and brake pad relative movement.

You can get a feel of cabling compressibility and/or hanger movement by seeing how much lever you can still pull after the pads have just hit the rim.

 

[KneesUp]

Thanks for all that information, @RecordAceFromNew

I've had a look at the bike having read your advice and discovered that the hanger was slightly loose and (ahem) that one of the blocks was a bit out of line, so I've moved that and tightened the hanger and I now have brakes that work and enough clearance to get the wheel off. The hanger bolt only took another 3/4 turn but it does seem to have made a big difference to how it flexes.

Thanks again all.