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increasing braking power on stock cantilevers

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shekky

· the half breed devil
Santa Cruz 5010 v.3, rigid single speed karate monkey
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Discussion starter · #1 ·
my cross bike (2011 GT series cx-1) rolled out of the shop on mafac-style tektro cantilevers.

sometimes when i descend long fire roads i feel as if i have no brakes but that's compared to the braking power of the discs on my hardtails.

what suggestions might some of you have to improve my GT's (stock) braking power--especially up front? i've just installed some fairly burly kool stop MTB pads on the cantis but is that going to do the trick?

thanks in advance for your thoughts, as always!
 

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#2 ·
Your rim looks glazed. Once you've overheated a rim, not much you can do. Roughing up the rim will only help for a very short period, and you're accelerating wear of the side walls.

The cool stops may be better as the original pads probably were also hardened due to excess heat.

Problem, though, is those long fire road descents. All brakes have a limited amount of heat they can absorb and dissipate over time. You might need to incorporate stops to prevent killing your stopping parts.
 
#3 ·
shekky said:
my cross bike (2011 GT series cx-1) rolled out of the shop on mafac-style tektro cantilevers.

sometimes when i descend long fire roads i feel as if i have no brakes but that's compared to the braking power of the discs on my hardtails.

what suggestions might some of you have to improve my GT's (stock) braking power--especially up front? i've just installed some fairly burly kool stop MTB pads on the cantis but is that going to do the trick?

thanks in advance for your thoughts, as always!
Click to expand...
Check your straddle cable angle, if you haven't already. Straddle cable geometry can have a lot to do with braking performance on cantilevers. Ideally your straddle cable should make a 90 degree bend or slightly wider as it passes the straddle cable hanger. As the angle between the legs of the straddle cable gets narrower than 90 degrees the amount of force applied to each brake arm decreases.
 
#4 ·
I had Kolo brake stiffeners on my old Zaskar. They look like horse shoe shaped plates which fit to each brake set. The braking improvement using them is significant not to mention consistent.

Came across a video on Youtube
 
#5 ·
Definitely lower the yoke on your straddle cable. It looks like you've got it pretty high, which is frequently done for extra rim clearance but sucks your braking power. Also, make sure the brake pads are exactly perpendicular to the rim when they make contact.

Check out this link for an interactive model of how the yoke height affects braking power: MAITOY: Cantilever Brake Geometry

If the link above doesn't show you a clear image, try a different browser. I'm having trouble viewing it in Chrome lately, but IE seems to work.

Next, if your fork will allow it get a fork-mounted cable hanger. In addition to giving you increased power, this will help eliminate any fork shudder you might be experiencing.

Make sure that you don't have any bad bends in your cable routing. Look especially at the noodle where the cable housing meets the hanger and try to eliminate any drag. You can also gain marginal improvement by switching to compressionless brake cable housing.

Once you've done the above if you're still not happy you might consider different brakes. I've been a lot happier with Shimano CX70 cantilevers than I was with the Tektro CR720's that it looks like you have. The CX50's supposedly perform the same at about half the cost but just don't have the nice finish of the CX70's. A lot of people rave about Avid Shorty Ultimates too (though you shouldn't expect Shorty 4's or 6's to do as well). Lastly, mini V's can be a great option, eliminating many of the problems with cantilevers at the cost of not having any adjustability. TRP makes some really nice mini-V's, but you can get really cheap ones that work pretty well.

Of course none of this will give you braking anywhere near what you get with hydraulic discs, but you can probably get a lot of improvement over what you're experiencing now.
 
#6 ·
Mini V-Brakes... I had a number of canty brakes, including Avid Shorty and TRP Eurox. Had them all dialed (humbly... I know how to get mechanical advantage out of my brakes)... Switched to V-Brakes (TRP CX9 & TRP CX8.4) half way through this cross season... and will NEVER go back. I can only think that for your application they would be FAR superior to what you have. The braking power is hands down better, with a slight decrease in modulation. Just a consideration.
 
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#7 ·
strat819 said:
Mini V-Brakes... I had a number of canty brakes, including Avid Shorty and TRP Eurox. Had them all dialed (humbly... I know how to get mechanical advantage out of my brakes)... Switched to V-Brakes (TRP CX9 & TRP CX8.4) half way through this cross season... and will NEVER go back. I can only think that for your application they would be FAR superior to what you have. The braking power is hands down better, with a slight decrease in modulation. Just a consideration.
Click to expand...
I've used mini-v's before and was not impressed. The power was there, but the feel was terrible, they were like a light switch. I could either go, or be stopped. I'd rather have poorly performing cantis than those mini-V's again.

To answer the OP's question, dropping the straddle cable is the way to go. There's a great writeup on Sheldon Brown's website for adjusting cantis:

Adjusting Traditional Center Pull Cantilever Bicycle Brakes
 
#8 ·
I like mini-Vs too. I did have to get used to the much faster braking action, but that's worked out fine. I have cheap ones, Tektro BX3v. For more money, most of the cyclocross-specific ones are available in a few arm lengths to match different brake levers.
 
#11 ·
shekky said:
thank you all for your good suggestions, but...please re-read the title to the thread.

my goal is not to buy new brakes, it is to increase the power of what i have already.

my straddle cable height could be a little lower...
Click to expand...
On my Zaskar, my cants stop as good as my disc brakes. In certain circumstances, they are better ( no kidding ).

1. Keep your rims clean, true. Use coarse wet and dry paper to roughen them if they are shiny.
2. Make sure your pads have a slight toe-in
3. Use Koolstops
4. Keep gap between pad and rim no more than 2.5mm
5. Ensure angle of straddle cable where it intersects with pull cable is no less than 100 degrees. I usually set mine between 110 and 120
 
Discussion starter · #12 ·
c8stom said:
On my Zaskar, my cants stop as good as my disc brakes. In certain circumstances, they are better ( no kidding ).

1. Keep your rims clean, true. Use coarse wet and dry paper to roughen them if they are shiny.
2. Make sure your pads have a slight toe-in
3. Use Koolstops
4. Keep gap between pad and rim no more than 2.5mm
5. Ensure angle of straddle cable where it intersects with pull cable is no less than 100 degrees. I usually set mine between 110 and 120
Click to expand...
for andrew, here's a photo. i hope you can get a better idea from that angle.

c8stom, i probably have three out of your five suggestions with the exception of the last two. actually, i think i need to toe my pads a little more because i'm getting some fork juddering with the new kool stops--which seem to stop waaaay better than the old kool stops.
 

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#13 ·
Yeah, that's the kind of brake I thought you were talking about.

So the deal with lowering the straddle cable is that as it approaches horizontal, the mechanical advantage of the vertical cable pulling on it gets ridiculous. Since the arms on your brakes stick out to the side, you can't get the kind of angle you'd be able to get with low-profile brakes. Making the arms longer would help, but that hardly seems like an option.

You might get a small improvement playing with the length such that the straddle cable is perpendicular to the actuation arms when you apply the brakes. I don't think it'll get you much joy, though.

Something that might help more would be to clean up your front brake cable's route. That angled piece in your cable stop may not be doing you any favors. Using a little longer housing and routing straight to the stop might be better. A cable stop on the fork could maybe let you mellow out the bend even more. Basically, the more friction there is in the system, the more force goes to fighting friction instead of squeezing your rim. You can even route that front cable up over the stem if you like.

I know you didn't want people to tell you to just get mini-Vs. But I know I fought this, and I bet a lot of other "just get Vs" people have too.
 
Discussion starter · #14 ·
"That angled piece in your cable stop may not be doing you any favors. Using a little longer housing and routing straight to the stop might be better. A cable stop on the fork could maybe let you mellow out the bend even more. Basically, the more friction there is in the system, the more force goes to fighting friction instead of squeezing your rim."

BINGO!
 
#16 ·
The gap between the rim and pad can be greater and the angles different . Really depends on how firm you like pulling the lever to feel. My setup feels like a disc brake and allows me to lock front or back wheels easily with 2 fingers for back hopping etc.
 
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c8stom
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