Don't like my brakes...

bigjim

because they don't stop me quick enough. They are Shimano Cantis and rubbish. I have had too many heartstopping moments with them. I do almost all my own work on my bikes and I can't improve these. Even my LBS had a go and still not good enough. I am used to the dual pivot sidepull on my race bikes. These Cantis are on my tourers. I have replaced the set on one bike with frogglegs, an improvement but fickle to keep set up and they stick out too much. Both frames are 531 so I am considering drilling them out to take sidepulls. I have no intention to fit tyres wider than 28mm so wonder if anybody has done this or knows of any problems. My LBS can't see why not as the brake bolt will take the strain rather than the frame. Any comments?

andrew_s

Bear in mind that long reach dual pivot brakes, which will be required to reach from the fork crown to the wheel rim regardless of tyre size, are significantly less powerful than the short drop dual pivots that you get on a road bike.
The extra reach in itself reduces braking force (eg 49mm drop to 73mm drop reduces braking to 67% of what it was), then on top of that the brake calipers are of lower quality and are less rigid.

I'd recommend that you look at mini-Vs, which will limit tyre size to 28mm or so but will allow your existing brake levers, or full size Vs with the V-compatible Tektro brake levers. This would mean bar-end or down tube shifters if you are currently STI/ergo.
You'd need to check if the width the brake bosses on your bike(s) was suitable. Older touring bikes tend to have narrow set bosses which force the V-brake arms to splay outward like they shouldn't

desweller

Cantilever brakes are a bit of a fiddle to set up but there's no reason why they can't generate good stopping power. May I ask what you've tried to get them working and what pads you have on there at the moment?

unixnerd

I have the solution :-) MY tourer was just like yours, went down Cairngorm on it once and had cramp in my hands by the bottom.

I bought Shimano mini-V brakes and a thing called a Travel Agent to adjust the pull ratio from mountain to road brake levers. Works like a charm! I actually have a complete spare set as there wasn't enough clearance with my pannier rack to fit them at the back. So if you fancy my spare set PM me and I'll take a pic of the setup for you.

cycleclinic

Straddle cable position has a big effect on the performance of canti brakes. Lowering the straddle wire will increase mechanical leverage. Canti's can be set up well.

If you have wide angle canti's the straddle cable then you need high mechanical levergae levers (i.e standrd dual pivot brake levers won't work so well).

Don't blame your canti's there is something wrong witrh your set up that needs addressing.

unixnerd

Don't blame your canti's there is something wrong witrh your set up that needs addressing.

I'm an engineer and I spent years trying to get mine to work better before I gave up and replaced them.

Hoopdriver

thecycleclinic wrote:

Straddle cable position has a big effect on the performance of canti brakes. Lowering the straddle wire will increase mechanical leverage. Canti's can be set up well.

If you have wide angle canti's the straddle cable then you need high mechanical levergae levers (i.e standrd dual pivot brake levers won't work so well).

Don't blame your canti's there is something wrong witrh your set up that needs addressing.

I agree. There is something dodgy with your set up. Cantis are perfectly fine brakes if set up properly. They are a fiddle but once set up are fine. Brake pads can make a difference as well. Koolstop salmons are very good.

I would not go down the V-brake and travel agent route. It is workable, but not very good.

bigjim

I don't think there is anything dodgy with the setup as I have had them set up by the LBS and done them by the book myself. I also have these on my MTB and they also have never been great but that is never ridden fully loaded. They do work ok on my tourer if it is unloaded but once loaded up and descending forget it. I admit I never thought it would be a problem fitting long drop sidepulls, re loss of power, as these are sold and used without any mention of this. Thanks for all the advice.

Monty Dog

If you don't need the tyre clearance then swap to a mini-vee like a Tektro CX5 - you don't quite get the modulation, but you do get lots of power - I run a set of mini-vees on one of my CX bikes and they're strong enough to hold the bike at the top of drop-offs. I run cantis on other bikes, but the quality does vary and with most, getting the set-up critical is key. Frankly, the older Shimano low-profile cantis are rubbish. Agree on looking at softer compound pads too.

cycleclinic

You wouold be surprised at how many people complain about the perfarmance of the canti's and it's down to the setup. Many shops don't know about them any more. some still do though.

Unixnerd I am also an engineer/physist now bike mechanic. So being an engineer has nothing to do with setting them up properly.

Lever mis matched with cantilever arms could be the issue, along with straddle cable height also pads could be issue. If a link cable is used instead of straddle wire there are 5 different length avaialble not that you can buy those easily or get a choice when buying your brakes. Chainging to a straddle cable and straddle cable hanger can solve this as you can set your straddle cable length to the height you want it set at.

Low profile canti's have high mechanical advantage I believe so need low mechanical advantage levers. Also they need a low straddle cable postion as when you pull the lever and the straddle cable rises the mechanical advantage plumits, hense the poor performance noted. Set the straddle cable low enough and performace should be accpetable but never brilliant. The best canti's in my opinion are wide profile ones (Mafec) as the mechanical advantage doe not drop as much when the lever is pulled.

As for long drop sidepulls if you need them for mudguard clearance you do not have much of a choice do you.

dw300

Couldn't this have something to do with pads? I have Shimano Sora brakes, pretty cheap stuff, which I thought sucked to begin with, but although it took a while to bed in they are now very effective.

cycleclinic

Pads are just one part of the brake system. How do your levers feel. Hard - that is the pad hit the rim with little lever travel if they do your brakes are not set up correctly, or spongy - that is once the pads hit the rim you can still pull the lever deforming the pads. The latter is the more effective setup.

Are your levers and brakes a matching set. any photo's of your set up.

bigjim

This is my current setup. The pads feel hard when lever is pulled. I have them set close to the rim. But only the straddle wire moves when lever is pulled. I'm suspecting the straddle wire is too short to bring the l/hand cati arm to the verticle to enable equal force?

unixnerd

You need to arrange it so the second notch point on the straddle wire is in the brake, that'll help. You also need to align the brake cantilevers so that they're at an equal angle when not under load, then adjust the pads towards the rim.

Lastly, you seem to be using pads with a plastic backing so only the centre of the pad is transmitting much force. Get some metal backed pads with interchangeable inserts. I have a spare pair you can have for a fiver inc. postage.

cycleclinic

Your issues are with the set up. The lever feeling hasrd is the giveaway. Mechanical advanbtage is too low!

1) replace that link wire with a traditional straddle cable and hanger. Your link wire is too long.
2) Set your straddle cable a lot lower. Set it below the 90 degrees between the brake arms and straddle wire that is often quoted as being the best.
3) ensure the canti arms are balanced that sittting symmetrically.
4) change the pads but only when everything is set up right. Koolstop work as do Swiss stop but I use Jagwire basics with O.K results.

It's all in the set up.

kentphil

what condition are the wheel rims in? perhaps this is affecting brake performance?

Hoopdriver

Yes, that set up is definately wrong, as noted above. If your LBS set that up you need to find an LBS that is familiar with cantis. Cantis may be fiddly to set up properly, but when they are, they are pretty useful brakes.

bigjim

Hi wheel rims probably less than 500miles. I've spent hours fiddling with this and I'm not known for my patience.
So I've thrown the ... things in a corner and fitted these in 30mins and I now seem to have a good solid brake. I don't know whether it is the proper thing for the frame but they fit the bridge easy enough and feel fine. If the rain ever stops I will go out and test them. If they are not good enough, will have to try mini Vs. I will never put a larger tyre on the front and will not fit front panniers. The thought of having to deal with those cantis on tour is a nightmare.

cycleclinic

It is a shame you gave up on them but at least you have a brake that works.

They are actually quite easy to set up. Having a stand really helps though as the bike is at least stable.

bigjim

I've not totally given up but I don't have other bits to try or the time to mess around any more. I may try again over the winter. There again it might be winter now. Thanks for all the advice.
Jim.