Help me with Canti brakes

[Dan Le foot]

So we sell our backup road bikes and hardtails and buy a pair of Kish Ti cross bikes for traveling.
Excellent decision. Just a quick change of tires and we are roadies and vice versa. No need to travel with 4 bikes.
We are using Paul touring cantilever brakes on both bikes. My 1st opportunity of setting these up. No problem on Michelle’s bike. (Record 10)
But I have been getting a wicked shutter from my front end under hard braking. (Shimano 7800)Scary stuff descending a 10% washboard road. I have adjusted the pads many times with different toe-in positions.
So what causes shuttering and how to I stop it?
Thanks.
Dan

[oldpotatoe]

So we sell our backup road bikes and hardtails and buy a pair of Kish Ti cross bikes for traveling.
Excellent decision. Just a quick change of tires and we are roadies and vice versa. No need to travel with 4 bikes.
We are using Paul touring cantilever brakes on both bikes. My 1st opportunity of setting these up. No problem on Michelle’s bike. (Record 10)
But I have been getting a wicked shutter from my front end under hard braking. (Shimano 7800)Scary stuff descending a 10% washboard road. I have adjusted the pads many times with different toe-in positions.
So what causes shuttering and how to I stop it?
Thanks.
Dan

Shutter is caused by a combo of fork flex and the fact that the cable stop is up by the stem. Reduce shudder either with a less powerful(and less stopping power) front brake, a fork mounted cable stop or a TRP CX-9 mini V brake(the best option).

[Peter P.]

oldpotatoe has it right.

Lennard Zinn explains it well here (http://velonews.competitor.com/2010/09/cyclocross/technical-qa-with-lennard-zinn-return-to-cross_101807) .

[Kontact]

A very inexpensive solution from Origin 8. Works very well, is only a hair heavier than a steerer mount and you won't have to buy new brakes:

http://www.origin-8.com/images/new_400/14521.jpg

[RPS]

Scary stuff descending a 10% washboard road.
Is washboard surface the only time "wicked shutter" happens, or only time it gets scary? And is Michelle descending the same grade along with you at similar speed without shutter while using same brakes? :confused:

If brakes work well on different surfaces, maybe something else like fork and/or frame flex may be to blame. It’s not likely, but possible to set up resonance between frameset flex and washboard pitch at a given speed.

I’d try the easy fixes first, but would remain mindful of flex if other remedies don’t work. I’d guess Michelle’s bike is of different size and her weight is different also, so her frame may act differently than yours. IMO there are too many variables to assume brakes are main problem.

[BengeBoy]

A very inexpensive solution from Origin 8. Works very well, is only a hair heavier than a steerer mount and you won't have to buy new brakes:

http://www.origin-8.com/images/new_400/14521.jpg

+1

I had shudder issue on my bike with canti's and got *many* opinions from bike shops on how to fix it -- new brakes, new pads, new adjustments. I tried a lot of things but this new mount fixed it immediately. Very happy with the result.

[Ken Robb]

All the discussion of "shutter" makes me shudder and think I have been shifted to a camera users' site. You know: shutterbugs. :)

The forks on my canti bikes are apparently stout enough that I get no shudder or squeaks. I had a bike that would get some squeal from its cantis when I didn't have LOTS of grease on the studs and/or pivot bearings. It wasn't that they were dry as much as lots of grease damped the squealing--I think.

[Dan Le foot]

+1

I had shudder issue on my bike with canti's and got *many* opinions from bike shops on how to fix it -- new brakes, new pads, new adjustments. I tried a lot of things but this new mount fixed it immediately. Very happy with the result.
I read the article by Zenn provided by Peter. I didn't realize how wide spred the problem was.
I'll give this product a try. Not sure I will be able to find one while we are traveling though.
What source do you use?
Thanks everyone.
Dan

[Chousen One]

Origin8 is through Action around the mid Atlantic, and many times available next day at many LBS's. If you're on the move day to day you could call ahead and have them order it, it's a small low cost piece and I doubt you'd even be required to place a deposit.

[Kontact]

At our shop we have them in stock. I'm sure some others do, too. Calling ahead one evening makes sense.


The funny thing is that this problem did not seem to affect mountain bikes. I think current cross bikes combine a long head tube and a long 700c fork in a way that makes it much more likely than with MTB dimensions.

In the meantime, I wonder if putting tension on the exposed cable by running a cord around it and the headtube would interrupt the shuddering and act as a damper? Easy enough to try.

[Jason E]

I did not see it on their website, what is it listed under?

JE

[Ken Robb]

The funny thing is that this problem did not seem to affect mountain bikes. I think current cross bikes combine a long head tube and a long 700c fork in a way that makes it much more likely than with MTB dimensions.



I suspect that the forks on mtn. bikes were/are stiffer than the ones that suffer from shudder. My 1989 MB-3 has never had this problem and neither has my Riv Allrounder or Hampsten Strada Bianca which has Alpha Q cross fork which I guess is no longer available?

[fourflys]

Dan,
I feel your pain... when I was running regular cantis, I had the same issue and that is why I switched to the CX9's mentioned... hopefully, the part mentioned above will help as well...

just curious, do both bikes have the same fork?

Chris

BTW- the best I ever got my cantis set up was using a business card folded in half under the back half of the brake pad to set toe-in... there are tons of techniques, but that one seemed to work best for me (least amount of shudder)...

[RPS]

I suspect that the forks on mtn. bikes were/are stiffer than the ones that suffer from shudder.
That's why I asked about other differences between his and Michelle's bike. If they both have the same brakes that were set up by same person, then it's a little odd that one appears to work fine and the other can't be made to work correctly. Something else might be missing, or is contributing to the problem beyond the brake itself.

[Onno]

I replaced the cantis on my cross bike with Tektro Mini-v brakes. They cost 12 bucks a piece (pads included), are very easy to install and set up, and work MUCH better than cantis. I think they are widely available, in part because they are so inexplicably cheap.

[John M]

My solutions in order of cost:

1. More toe-in on brake pads
2. Higher straddle cable--The Paul touring canti instructions say to run the straddle 3 inches above the tire. This is too low for the front, in my experience. Run the straddle cable about 10-12 cm above the tire on the front. On the rear 3 inches or even less is fine.
3. Fork mount cable stop--As mentioned above, but only a viable solution if your fork is drilled in the crown. Many carbon forks are not.
4. Use a different type of brake, such as a mini-V.
5. Stiffer fork. I had shudder with the Easton 90X cross fork that was reduced quite a bit with solutions one and two above, but was completely eliminated with replacement with an Edge cross fork.

[Dan Le foot]

Dan,
I feel your pain... when I was running regular cantis, I had the same issue and that is why I switched to the CX9's mentioned... hopefully, the part mentioned above will help as well...

just curious, do both bikes have the same fork?

Chris

BTW- the best I ever got my cantis set up was using a business card folded in half under the back half of the brake pad to set toe-in... there are tons of techniques, but that one seemed to work best for me (least amount of shudder)...
Hi Chris.
Both forks are Envy cx.
The only difference between the two bikes is Mic's is a 52 and mine a 58. She weights 110 and me 180. She is running Campy 10 and me 7800. I built up both bikes.
No shutter today. Than again we are in Rexburg Id. right now and had 74' of climbing in 25 miles. (not exactly the hills of San Diego north county)I don't remember touching the brakes. :beer:

[Dan Le foot]

My solutions in order of cost:

1. More toe-in on brake pads
2. Higher straddle cable--The Paul touring canti instructions say to run the straddle 3 inches above the tire. This is too low for the front, in my experience. Run the straddle cable about 10-12 cm above the tire on the front. On the rear 3 inches or even less is fine.
3. Fork mount cable stop--As mentioned above, but only a viable solution if your fork is drilled in the crown. Many carbon forks are not.
4. Use a different type of brake, such as a mini-V.
5. Stiffer fork. I had shudder with the Easton 90X cross fork that was reduced quite a bit with solutions one and two above, but was completely eliminated with replacement with an Edge cross fork.
Thanks John.
I'll try 1 and 2 above. I have The Edge cross fork with out the drilled crown so I guess the solution above won't work.
How does the higher straddle cable help if you know?
Dan

[veloduffer]

On my Kish and Serotta cross bikes, I put the Tektro CX-9 mini-V-brakes on the front and kept the cantis in the rear - no more shudder. It's a very common occurence with cross bikes and cantilever brakes. Since you don't need absolute stopping power for cross bike racing (just modulating your speed), cantilever brakes suffice. But for out on the road in traffic, stopping power is more imperative.

Besides eliminating shudder, the mini v-brakes are easier to set up and require a lot less hand pressure on the brakes. The only downside is the pad/rim clearance is much smaller and taking the front wheel off may require some deflation (if you have a wide tire).

[Ken Robb]

That's why I asked about other differences between his and Michelle's bike. If they both have the same brakes that were set up by same person, then it's a little odd that one appears to work fine and the other can't be made to work correctly. Something else might be missing, or is contributing to the problem beyond the brake itself.
There is a lot more weight on Dan's bike and the steerer length is different.
I suppose you have cleaned the rims on the shuddering bike to eliminate vibration caused by varying degrees of friction, right?

[Dan Le foot]

There is a lot more weight on Dan's bike and the steerer length is different.
I suppose you have cleaned the rims on the shuddering bike to eliminate vibration caused by varying degrees of friction, right?
I'll give it another real good cleaning, Ken.
dan

[RPS]

There is a lot more weight on Dan's bike and the steerer length is different.
I suppose you have cleaned the rims on the shuddering bike to eliminate vibration caused by varying degrees of friction, right?
Isn’t the greatest degree of variation in friction in this reported case likely caused by the road surface?

What Dan implied in the OP that got my attention was that it shuddered while braking on a washboard road; going down a 10 percent slope. IMO if you apply brakes hard on any bike (it’s even happened to me driving vehicles off road) on a washboard surface the tires will load and unload as they grab and release traction at a frequency dictated by the road surface and bike’s speed.

[jamesutiopia]

I would speculate key difference here is probably the length of the head tube if you are using a spacer-mounted cable hanger. Per Zinn's article the problem is the long length of the un-dampened cable from the hanger to the brakes themselves, which is a few cm more on your taller frame.

The fork mounted hanger solves the problem by making the unsupported/dampened length of cable very short (so the resonance situation still exists in theory, but is not a practical concern).

Mini-Vs work, but not everyone loves the lever feel (improve it by getting the hardest pads you can find-- Swissstop green work better than Koolstop salmon in this case) and they aren't great with fenders. They also come in multiple arm lengths (80mm, 85mm, and 90mm) which work better/worse with various brake levers. The cheap Tektros are usually 80mm long and the expensive Tektros (CX-9) are 90mm. Campy once made a mini-v brake that was 85mm long.

The other thing to think about if you try mini-v brakes is the post spacing vs. rim width. Cantis can be tuned to work well with a variety of combinations but mini-vs need a lot of space to work well (e.g. a wide rim like 24mm wide Velocity Synergy combined with narrow posts will be bad).

If it's only an occasional situation you can reach down and dampen the cable movement yourself... :)

[acckids]

I have an Alpha Q CX20 and gave up on the canti's. I got tired of the shudder and everyone telling me I didn't have my cant's set up correctly. I like to grab my bike and ride; not mess with the brakes.

I went cheap with the Tektro Rx 5 mini V. The arms were 85mm. They actually stop me plus the shudder is minimal and the shudder is only present going from 22mph to a quick stop.

The mini V give plenty of clearance also/see below.

[Kontact]

I did not see it on their website, what is it listed under?

JE
They're listed under cables.


This shuddering is a cummulative effect, I think. It requires a long, softer riding fork, a long cable (like the one on a 58), a certain rim surface, etc. You can probably break the chain at any one of those points, but using a $5 cable hanger makes a lot more sense to me than changing out a fork you like or using brakes that require adapters and don't truly quick release for wheel changes.

Those Origin 8s work on the rear pretty well, too.



I recall another sort of canti adapter in years past. It mounted to the fork center hole, but pivoted. A little L shaped thing. Anyone remember what those are?

[Dan Le foot]

Isn’t the greatest degree of variation in friction in this reported case likely caused by the road surface?

What Dan implied in the OP that got my attention was that it shuddered while braking on a washboard road; going down a 10 percent slope. IMO if you apply brakes hard on any bike (it’s even happened to me driving vehicles off road) on a washboard surface the tires will load and unload as they grab and release traction at a frequency dictated by the road surface and bike’s speed.
Hi RPS.
It will shutter on any surface when front braking agressively.
More scary on the washboard.
Dan

[palincss]

I hate to be pedantic, but please - the word you are looking for is shudder. A shutter is something you find on a camera, or put in front of a window.

[mso]

I hate to be pedantic, but please - the word you are looking for is shudder. A shutter is something you find on a camera, or put in front of a window.


Bet that made you feel good :banana:

[Ken Robb]

Bet that made you feel good :banana:

It made me feel good---but that's easy these days. :beer:

[trevorluke]

I've had terrorable trouble with the TRP cantis on my cross bike, so I feel you pain! I just swithced to their mini v-brake and it works great. So now I'm running a v-brake in the front and the canti in the rear, saving hours of hassles. I would recommend this solution. It seemed like I could get the cantis to work without shudder for a while, but it would always come back.

[John M]

Using a longer (higher position) straddle cable on cantis increases the modulation, and decreases the overall power of the brake. This will reduce the tendency of the brake to grab and release, which is what causes shuddering. Too long of a cable position will reduce braking power too much, but in cross racing, brakes are used mostly for slowing and controlling speed rather than stopping, especially from lower speeds than encountered on the road, so massive stopping power isn't that big of a deal. That said, with the Paul touring canti and a higher straddle position, I still have plenty of stopping power, even when riding my cross bike down steep hills on the roads here in Seattle.