Cantilever brakes: reducing stopping distance

tomasrojo

Hi everyone,

I've been using V-brakes for years, but my new touring bike (Dawes Horizon) has cantilever brakes (Tektro Oryx).

I'm find that stopping distance is quite a bit longer that I've been used to, which has given me a surprise on one or two occasions.

Perhaps a superior brake pad would let me stop sooner? Anyone have any quick recommendations? I've seen Kool Stop mentioned somewhere.

DirkVoodoo

Yes, Kool Stop Salmon (Wiggle)

Other, cheaper alternatives include: keeping your rims and pads clean and free of debris and grime or perhaps if you tell us how you normally brake, i.e. do you favor the rear brake over the front brake?

I would imagine that losing the superior mechanical advantage of cantis can be quite unsettling at first, but I have never really found I needed extra braking force on the road. Well, I did once, but that was because I reinstalled my brakes incorrectly!

tomasrojo

DirkVoodoo wrote: »

I would imagine that losing the superior mechanical advantage of cantis can be quite unsettling at first, but I have never really found I needed extra braking force on the road.

I'm finding the cantilever brakes a bit inferior in terms of mechanical advantage so far. Not awful, they just don't grab the rim the way the V-brakes did on my older bikes.

The rims are clear; I gave the bike a wash at the weekend, but the stopping times are still a bit disappointing.

I usually use both brakes in an unexpected stop, but I'd squeeze the front far harder. I use the rear brake mostly for going over ice and gravel, or when I'm signalling right.

penexpers

I get the impression that Oryx are not really regarded as great cantilever brakes. I'm currently using mini-V's and they are not great, so I am going to try out some Tektro CR520's soon.

blorg

I have a fair bit of experience with cantis and (mini) V brakes on road bikes and you are not wrong, the braking is substantially worse than either road levers+calipers or flat bar levers+V brakes. Pads will not help here I fear. The mini Vs do work better than the cantis but they are a little fiddly and you have to set the pads VERY close to the rim, which causes problems if your wheel gets even slightly out of true. Next thing I am going to try is wide profile cantilevers.

dave2pvd

penexpers wrote: »

I get the impression that Oryx are not really regarded as great cantilever brakes. I'm currently using mini-V's and they are not great, so I am going to try out some Tektro CR520's soon.

I agree 100%

I have Tektro CR720s (pictured; note the critical 90deg hanger cable configuration) on my CX bike and they are more powerful than the Ultegra set-up on my road bike. Both using standard pads.

There are some very good cantis and some very mediocre cantis.....

Lumen

dave2pvd, any chance of a proper picture of that bike? Looks interesting.

Single Malt

Canti brakes are at a mechanical disadvantage to "v" brakes. The levers pull less cable, causing the modulation to suffer. Also the lever ratio in canti brakes gives you less power than "v" brakes. There is a reason "v" brakes replaced canti brakes on mtbs in the mid 90's;)

dave2pvd

Single Malt wrote: »

Canti brakes are at a mechanical disadvantage to "v" brakes. The levers pull less cable, causing the modulation to suffer. Also the lever ratio in canti brakes gives you less power than "v" brakes. There is a reason "v" brakes replaced canti brakes on mtbs in the mid 90's;)

With the bike pictured I can lock up either wheel in the dry. With perfect modulation. As I fly over the handlebars.

It's just physics. Less cable pull means more leverage is needed. See how wide the CR720s are? The pivot -> cable bolt is long, the pivot -> brake pad is short. Plenty of multiplication there. You don't see that with the Oryx model.

I've seen some heated debates about touring canti vs low pro canti vs V-brakes. I did a lot of reading up before determining that the 720s would work well with Ultegra levers. They appear to have similar geometry to what the pros use, like Paul and TRP Eurox. Only at 1/10th the price.

dave2pvd

Lumen wrote: »

dave2pvd, any chance of a proper picture of that bike? Looks interesting.

Sure Lumen.

It's a compact-ish 56cm Fuji Cross Pro with Mavic Aksiums, Ultegra RD & shifters (triple!), Truvativ 5-bolt 110mm crank, FSA shallow drops, a flexy Richey stem, a 130g saddle that is a wee bit tough going, Maxxis Raze tires, a lovely made-in-Georgia Thomson seatpost, eggbeater SLs and CR720 cantis.

The bike gets used on the road just as much as my race bike does. It's basically my training bike. Weighs in at a shade under 20lbs. I have all of $750 in it:

Single 42 ring up front with 'bash' ring and dog fang:


Sorry about the poor quality:


CR720s:


Ultegra RD. SRAM, Ultegra or 105 sprockets. Looks like the SRAM 11-23 in this pic:

BostonB

Someone set the pads on my MTB (with canti's) really close to the rim, and it transformed the brakes. I was setting them just that bit too far back. Now they can lock the wheel no problem.

dave2pvd

Here's a setup guide from the L Zinn book: Mountain Bike Performance Handbook

I liked this comment, from Plusonelap: "This post isn't about whether cantilever brakes are the best option for cyclocross, that's already been decided. Verdict: they are".

The previous post helped me find this old gem, from the Godfather himself, Sheldon Brown: Cantilever Brakes

tomasrojo

I wrote a thanks to everyone, but it hasn't appeared.

So once again, thanks everyone. Very helpful.

I guess in the short term I'll keep the pads very close to the rim and keep the wheel very true.

On the bright side, I'll be replacing the brake pads less often. There seems to be far more rubber on cantilever brake pads.

blorg

Keeping the pads close works with mini-Vs, I don't think it will make any difference with low-profile cantilevers (the cantis I have, Shimano Altus, I think even more low-profile Oryx.) Note Dave's cantis are wide-profile, sticking right out from the wheel, I think this makes all the difference.

My cantis:



Cantilever angle is key I think

Sheldon Brown wrote:

Wide profile cantilevers have a cantilever angle much greater than 90 degrees. The best example of this type is the old Mafac cantilevers, in which the anchor arm actually sloped downward from the boss in some installations. This design is now pretty much obsolete. Wide profile cantilevers have rather low mechanical advantage, and work well only with levers with a high mechanical advantage.

Medium profile cantilevers have a cantilever angle of around 90 degrees. Most late-1980's cantilevers belong to this family. Medium profile cantilevers are very forgiving and give excellent all-around performance with a wide range of set-ups.

Low profile cantilevers have a cantilever angle of less than 90 degrees. The principal advantage of narrow profile cantilevers is that they don't stick out so far from the frame or fork. This is a very desirable thing, because protruding cantilever arms can cause a multitude of problems, particularly in the rear, where a rider's feet may hit them. Narrow profile cantilevers are also capable of excellent performance, but only if properly set up. A carelessly set-up low-profile cantilever may have very low braking power, even though it feels great on the workstand.

...

The lever's mechanical advantage is determined by the distance from the lever's pivot to the cable end, and by the effective length of the brake lever from its pivot to where the rider's fingers grip it. Typical mountain-bike type brake levers give a mechanical advantage of around 3 1/2, old-style drop-bar levers around 4, and "æro" drop-bar levers around 4 1/2. Levers for direct-pull ("V-type") brakes are around 2.

This would suggest to me that low-profile cantis are going to work best with "æro" drop-bar levers (which have the highest mechanical advantage.)

Apparently with low-profile ones you can look at changing the yoke cable.

@dave2pvd- how close do you have your pads to the rims? I am imagining with wide profile you don't have to go crazy close?

dave2pvd

blorg wrote: »

@dave2pvd- how close do you have your pads to the rims? I am imagining with wide profile you don't have to go crazy close?

blorg, I set them as close as possible, plus a millimeter or so to account for wheel deflection, just like my road bike.

Good job posting up that diagram. Note: it has an error, it should depict the brake pads touching the rim. That's when you want maximum mechanical advantage.