Cyclocross - Love my cross, hate it's brakes - are discs the way to go?

2008 Brodie cyclocross with tektro cantilever brakes and they suck. I tried different pads and nothing helped much. I see two options, Mtb lever brakes or discs. My frame is disc compatiable, but I'll need to get a front fork.

Has anyone made the jump to discs on their cross. Was it worth the extra weight? Are MTB brakes the best option between wieght and braking power?

Thanks

Canflyboy

I use tektro oryx and their wide-profile cantis and both work super awesome. You should mess around with setup first because they're good brakes.

Not saying you don't know what you're doing, but maybe it's the adjustment. If you don't know how to adjust them, check out this video. http://bicycletutor.com/adjust-cantilever-brakes/

I've played with the adjustment many times as did a menchanic from a pro cycling team. Maybe its the rim?
These brakes require a lot more effort to stop that any of my other six bikes (well not the track bike).

They're a little mushy and spongy.

If you're not competitively racing, there are few good arguments against discs. Discs give better power, linear response, clear mud and moisture better...what's not to like?

I've played with the adjustment many times as did a menchanic from a pro cycling team. Maybe its the rim?
These brakes require a lot more effort to stop that any of my other six bikes (well not the track bike).

They're a little mushy and spongy.

Maybe you've already tried this, but it's easy to overlook- the brake posts have a series of concave washers, some are thicker than the others. If you have the wrong thickness on the inside you won't get good braking no matter how you set them up. It's either the thick or thin washers on the inside. If your brakes look like they slant too far into the rim and the thin washers are on the inside, then put the thick on the inside. If your brakes look like they slant too far away and the thick are on the inside, put the thin on the inside.

I've played with the adjustment many times as did a menchanic from a pro cycling team. Maybe its the rim?
These brakes require a lot more effort to stop that any of my other six bikes (well not the track bike).

They're a little mushy and spongy.

Cantis are quite different from the brakes that pro road teams use. *Very* different! Set-up right they are much more powerful - so much so that they feel "mushy and spongy" set up correctly because they squash the brake pad against the rim in a way that eg centre pulls don't have the power to do.
So it's possible that your brakes are in adjustment but that you're not stopping because:

1. The brake pads are poor - if you have any doubt at all replace them with Kool Stops, the Salmon or Duals if you ride in the wet

2. Your braking technique is wrong because you're being thrown off by the to-you odd feel

3. Your brakes are slowing the rim, but your tyres have poor adhesion.

It is also possible that your cantis aren't feeling "truly" spongy and you have just mis-described them, read

www.sheldonbrown.com/cantilever-geometry.htm (http://www.sheldonbrown.com/cantilever-geometry.htm)

www.sheldonbrown.com/cantilever-adjustment.html (http://www.sheldonbrown.com/cantilever-adjustment.html)

and tell us what cantis, rims, pads and tyres you're using as well. .

Cantis are still the preferred stoppers for performance tandems - and these are bikes that need several times more stopping power than any other. At least one type of canti can brake a tandem fast enough to lift the 350-400lbs mass of bikes and riders using the front wheel as a pivot! That your brakes are cantis is not your problem.

If you're not competitively racing, there are few good arguments against discs. Discs give better power, linear response, clear mud and moisture better...what's not to like?

Spending the money to have the frame modified and buy a new fork. Increase in weight. Two more unboltable components that a have thief attraction rating.

Discs are great but they have their drawbacks, and going to them just because you can't get a set of cantis to work properly doesn't make sense.

Also standard discs aren't compatible with standard cross/road brake levers. The OP would need a special model like the Avid BB7 ***Road*** Disc Brake, NOT the MTB version!

Just ordered a set of tektro cr720's. We'll give them a try first before I add the weight and trouble of the discs. Will let you know how it works out.

I found adding a brake booster to the rear cantibrake made quite a difference.
http://i22.photobucket.com/albums/b337/plodderslusk/P1010339.jpg

You really don't need much braking power in the rear. You'll just skid the tire.

If you're not competitively racing, there are few good arguments against discs. Discs give better power, linear response, clear mud and moisture better...what's not to like?

The fact they they add about 1.6-2.0lbs at the wheels.

If you're not competitively racing, there are few good arguments against discs. Discs give better power, linear response, clear mud and moisture better...what's not to like?

Squealing, rotor bending/truing, aligning calipers to avoid pad rubbing, line bleeding (if hydraulic), weight, special forks & wheels, limited options for road lever compatibility, risk of locking out if you push lever with wheel off.

Don't get me wrong though, I absolutely love the power and feel of disc brakes. Just drives me nuts sometimes with the issues they bring.

+10000 on the Sheldon Brown article. Helped me immensely the first time I had to set up some Cantis. Read it once, then read it again. If you fully understand all of the principles it lays out and properly apply them in setting up your brakes, and they still persist in showing poor performance, that's when it's time to try another brand or type of braking system.

Cantis are quite different from the brakes that pro road teams use. *Very* different! Set-up right they are much more powerful - so much so that they feel "mushy and spongy" set up correctly because they squash the brake pad against the rim in a way that eg centre pulls don't have the power to do.
/snip/
Cantis are still the preferred stoppers for performance tandems - and these are bikes that need several times more stopping power than any other. At least one type of canti can brake a tandem fast enough to lift the 350-400lbs mass of bikes and riders using the front wheel as a pivot! That your brakes are cantis is not your problem.
Mark Abele at Rivendell, who runs cantis on all of his bikes and who Rivendell says is "the best cantilever brake adjuster in the land" said to me via e-mail that dual pivot calipers have superior stopping power to cantilevers. He said the sole reason to spec cantis is for fat tire and fender clearance.

So all this talk about the superior power of cantis is just hooey.

You can also do the math on the stopping power as well, but I don't feel like doing it right now. It's basic geometry and mechanical advantage calculations though.


Spending the money to have the frame modified and buy a new fork. Increase in weight. Two more unboltable components that a have thief attraction rating.

Discs are great but they have their drawbacks, and going to them just because you can't get a set of cantis to work properly doesn't make sense.

Also standard discs aren't compatible with standard cross/road brake levers. The OP would need a special model like the Avid BB7 ***Road*** Disc Brake, NOT the MTB version!
The OP said his frame is already compatible. He'll just need a fork. The Nashbar CX fork is a Winwood muddy without the label, and is highly affordable. I also fail to see the problem in your bold text, as the mechanical BB7 is a fine brake...so is the Shimano R505 road disc.


Squealing, rotor bending/truing, aligning calipers to avoid pad rubbing, line bleeding (if hydraulic), weight, special forks & wheels, limited options for road lever compatibility, risk of locking out if you push lever with wheel off.

Don't get me wrong though, I absolutely love the power and feel of disc brakes. Just drives me nuts sometimes with the issues they bring.



Squealing is a notorious cantilever problem. A lot of the other issues you raise are for hydraulics, which doesn't apply here. And how is disc caliper alignment more difficult than the arcane art of cantilever setup?

As an aside, disc brakes don't have the cosine error that cantilevers do. This is a big plus in their favor.

Mark Abele at Rivendell, who runs cantis on all of his bikes and who Rivendell says is "the best cantilever brake adjuster in the land" said to me via e-mail that dual pivot calipers have superior stopping power to cantilevers. He said the sole reason to spec cantis is for fat tire and fender clearance.


Ah. Argument from authority.

Just because Rivendell say their guy is the best means nothing. Zip. Nada. As in "They would."

Firstly, from an engineering point of view, ***you cannot divorce stopping power from permitted tyre width***. Either brake can lock its wheel - it's tyre width that decides how much braking the point just before lock provides.

Secondly, braking force on the wheel isn't Mechanical Advantage - which is the error that I think you and your Authoritative One have made. MA is about the multiplier on hand force at the brake - nothing else. What produces actual braking power is (doh!) force applied at the brake. High MA means nothing if the brake can't move the pads a sufficient distance to squash them. The more squashing the better. Dual pivots are much more restricted than cantis in travel, which is why they have to be set close to the rim, and hence in braking power. Which one again, despite the misconceptions of a thousand half-smart vulgarians, is NOT the same as MA.

Thirdly, it's quite easy to set a canti for the same mechanical advantage - or higher than a dual pivot. It just won't be a very good brake any more, because pad travel will be so small that braking force will no better than a dual pull, and with a standard canti design you'll be limited to skinny tyres because of the yoke angle.

Fourthly, there are no dual pivot equivalents of the several boosted canti designs.



So all this talk about the superior power of cantis is just hooey.


Based on someone telling you their guy is Teh Greetest! and his telling you what to think. Sure.



You can also do the math on the stopping power as well, but I don't feel like doing it right now. It's basic geometry and mechanical advantage calculations though.


Wrong.

You can deduce MA by geometry - until you get into the boosted designs - but once again, this IS not the same as stopping power!

And calculating MA for cantis and dual pivots isn't quite as simple as you think, as MA changes as the brake closes.

To calculate actual braking power you'd have to take the more complex version of these calculations - which I am sure are quite beyond you - and feed it into a model of the brake pad. That squashiness that a canti creates and a dual pivot, because of its limited travel, doesn't, is everything.



I also fail to see the problem in your bold text, as the mechanical BB7 is a fine brake...so is the Shimano R505 road disc.


Sure. But he needs to know to buy a road disc rather than the "mountain bike brakes" he had referred to.



Squealing is a notorious cantilever problem. A lot of the other issues you raise are for hydraulics


Vague and wrong. For instance, mechanical disc brakes do weigh quite a bit more than cantilevers!



And how is disc caliper alignment more difficult than the arcane art of cantilever setup?


I never mentioned disc alignment.



As an aside, disc brakes don't have the cosine error that cantilevers do. This is a big plus in their favor.

Congratulations on knowing a technical term! In practice I'd say that reduced rim wear matters more. Cosine error, like non-linear response, is something the sophisticated computers that control bicycles adapt to very easily. Braking is done in a feedback loop, not by looking at a corner and the speedo and going "Oh yeah - that's an 8lb pull for 2.3 seconds."

Ah. Argument from authority.

I see no problem with citing an experienced mechanic. No matter what you may think about Rivendell, a lot of them have been around the bike business for some time. While I find your goal of dismissing my post via invocation of formal fallacy to be novel (at least around here), I also don't think it is valid. Lord forbid we ever invoke an expert... :rolleyes:

Firstly, from an engineering point of view, ***you cannot divorce stopping power from permitted tyre width***. Either brake can lock its wheel - it's tyre width that decides how much braking the point just before lock provides.
Quite right. But the disc tends to win in both linearity and constancy regardless of environmental conditions.


Secondly, braking force on the wheel isn't Mechanical Advantage - which is the error that I think you and your Authoritative One have made.
Mechanical advantage is not the fulcrum upon which my point turns. It has some minor relevance when comparing different brakes and their effectiveness with the cable pull allowed by a "road" lever though. Your reading comprehension is clearly lagging though, since my "Authoritative One" never once utilized this term. Are you purposefully creating straw men, or is this simply an unfortunate side-effect? Either way, you are starting to make foolish assumptions.


Which one again, despite the misconceptions of a thousand half-smart vulgarians, is NOT the same as MA.
Never said it was.


Thirdly, it's quite easy to set a canti for the same mechanical advantage - or higher than a dual pivot. It just won't be a very good brake any more, because pad travel will be so small that braking force will no better than a dual pull, and with a standard canti design you'll be limited to skinny tyres because of the yoke angle.
Sure, but you're getting hung up on MA to a degree that I don't understand. Why would one do a setup like this?


Based on someone telling you their guy is Teh Greetest! and his telling you what to think. Sure.

Your assumptions are getting ridiculously belligerent now.


To calculate actual braking power you'd have to take the more complex version of these calculations - which I am sure are quite beyond you - and feed it into a model of the brake pad.
And now you're just being foolish. Typical "keyboard tough".



Vague and wrong. For instance, mechanical disc brakes do weigh quite a bit more than cantilevers!
Sure they do. I said that "a lot" of the issues raised applied to hydraulics. I did not way that "all" applied. You've done very well in re-stating this for me, with some added - and unnecessary - "eff you" thrown in. Well done.



I never mentioned disc alignment.
You also never mentioned that you didn't understand that "kenshinvt" said it, and that I was quoting him.



Congratulations on knowing a technical term! In practice I'd say that reduced rim wear matters more. Cosine error, like non-linear response, is something the sophisticated computers that control bicycles adapt to very easily. Braking is done in a feedback loop, not by looking at a corner and the speedo and going "Oh yeah - that's an 8lb pull for 2.3 seconds."
Congratulations on being exceedingly foolish. You haven't the slightest clue who I am, and you are making a great many assumptions. I love forum "toughs"...Always willing to shoot from the hip before they know who they're actually talking to.

Oh well. Done with this thread.

To the OP; I hope you find a satisfactory solution.

While we're back on cantilever brake adjustment, a quick question that's been on my mind. I have the Tektro CR720 brakes which are very wide - so wide in fact that the arms point out perpendicular from the rims. In most diagrams on cantilever adjustment (including Sheldon's), the arms stick much closer to vertical - parallel to the rims.

Question: Does this have any effect on Sheldon's (or other people's) advice on how to set up the brake cables? Does the same rule still apply - raise the yoke cable (further from tyre) for less MA, lower it for more?

You can increase the power by using a shorter straddle cable. If you have noise problems that cant be cured by toe-in, a bridge like plodderslusk uses will fix.

While we're back on cantilever brake adjustment, a quick question that's been on my mind. I have the Tektro CR720 brakes which are very wide - so wide in fact that the arms point out perpendicular from the rims. In most diagrams on cantilever adjustment (including Sheldon's), the arms stick much closer to vertical - parallel to the rims.

Question: Does this have any effect on Sheldon's (or other people's) advice on how to set up the brake cables? Does the same rule still apply - raise the yoke cable (further from tyre) for less MA, lower it for more?

everything still applies, just pay attention to the geometry and make the proper corrections.

To calculate actual braking power you'd have to take the more complex version of these calculations - which I am sure are quite beyond you - and feed it into a model of the brake pad.


And now you're just being foolish. Typical "keyboard tough".

This thread just degenerated into a couple of adolescent boys calling each other names. Why don't we keep it on topic and cut out the insults.

Congratulations on being exceedingly foolish. You haven't the slightest clue who I am, and you are making a great many assumptions.

Actually I know exactly who you are - you're someone who thought that calculating the mechanical advantage in a cantilever was a matter of "simple geometry". I.e. you didn't realize that it would vary as the canti arms moved. Nor did you realize that the MA of a canti brake is a function of the yoke angle (and the clearance, although that is often overlooked) and that if you were to configure a canti to work only under the same cirucmstances as a dual pivot it's MA would increase considerably.

If those two pieces of high school physics were beyond you I think it's fair to say that you won't be able to cope with the much more complex equations that result from modeling a brake block...

Anyway, if the OP wants more MA - ie to have to squeeze less hard on the levers - then all he has to do is set up his brakes with minimal rim clearance (rather than the huge mud gap common on crossers) and to move the yoke closer to the wheel - say to the bottom of the fork. If he is the cautious type he might want to install one of those little widgets that will hold the straddle cable if it there is a break - a straddle cable caught in a knobbly tyre can be very nasty.

If he really needs the mud gap - which most MTB riders get by without (riding on trails reduced to mud *is* considered an act of vandalism outside a race) - then MA will suffer but he should still move the yoke down. (The reduced clearance matters because with standard cantis MA decreases as the brakes move in - so the less far the cantis have to move before reaching the desired level of braking, the higher the MA will be at that point.)

The practical limits on increasing MA this way are:

1. The straddle cable intersecting the tyre (not really a great problem with crossers)

2. More MA means more cable travel. That means setting up the brakes with either less rim clearance and/or - the point overlooked by people who don't understand the difference between MA and actual braking power - less maximum squashing of the pad and hence less maximum brake.

However, I'm not sure that it is smart to increase MA to the point that I'd have it set on a canti braked MTB. The thin knobblies on a cross bike have much lower adhesion than MTB offroad tyres, so it's much easier to over-brake and send the bike into a skid - and more MA would make this worse. I'm sure that I can at least double the MA of my current bike's brakes (MA flies through the roof as the yoke moves down) but I won't bother unless I decide to put road tyres on and keep it mostly on the road. Or find narrow offroad tyres with much greater grip, which I don't expect. Otoh, a rider with lower hand strength could benefit from more MA. Ymmv.

Actually I know exactly who you are

Meh. Welcome to "ignore".

Now, for a serious question for the cyclocross crowd;

For all the people running "short" profile cantilevers, why not use 57mm reach dual pivot calipers? Stepping around the logical, and logistical answer of almost no frames currently being manufactured that are appropriate for 'cross and spec'd with those brakes, I offer the following:

Correct me if I'm wrong, but for UCI sanctioned events, isn't the max tire size allowed 35mm? A 57mm reach caliper like the Tektro R538 will fit a 35mm tire, or a 32 plus fenders.

If you look at the pics in this article (plus read the commentary about the setups and stopping power), the mud clearance is only marginally worse than the short cantilevers here. Velonews cantilever cyclocross article. (http://www.velonews.com/tech/report/articles/9054.0.html)

When one considers that, unlike MTB races, a 'cross racer can have a fresh bike waiting for him/her at each lap, plus the benefit of a wash station...I think a 57mm reach caliper would work nicely on everything save for the most peanut-buttery mud.

Banzai,

I dont see what the advantage of going to a long reach caliper brake would be. When my cantilever brakes are adjusted to my liking they stop great. In my opinion most of these posts about people hating their brakes comes from people who for, whatever reason, dont have their brakes properly set up, or are you using some terrible stock pads. My avid 4s with with a yoke and transverse cable seem to stop a lot better than my road brakes, and I would certainly miss the ability to change their feel at the lever if I moved to a caliper brake.

I do think calipers would be awful in most areas as most mud, even the rare mud in the SW, would clog them almost immediately. That large piece of aluminum over your tire will certainly hold a lot more mud than a straddle cable.

Also, your argument about the tire width does not take into account the overall radius introduced by knobby tires. I imagine you would be forced to use something that is narrower than the 35mm allowed by the UCI, which only applies to UCI races which are a rare occurrence in North America. In addition, I doubt too many posters on this board have a back up bike along with a mechanic to wash it.

To move to caliper brakes you would have to show that they have a significant stopping advantage over low profile cantis that are set up well, and I just dont think that is the case. Disc brakes, which add weight, but have clear advantages in stopping power, especially in cross races, are the more arguable position, in my opinion.

jonestr,

It was just a random thought as I briefly pondered the dimensions in question, so I thought I'd pose the question. It seemed workable for a bike appropriately drilled and for a person who hates cantis...provided the course isn't a super muddy one.

I'm a disc fan anyway.

jonestr,

It was just a random thought as I briefly pondered the dimensions in question, so I thought I'd pose the question. It seemed workable for a bike appropriately drilled and for a person who hates cantis...provided the course isn't a super muddy one.

I'm a disc fan anyway.

sounds like we probably agree

Banzai,

I dont see what the advantage of going to a long reach caliper brake would be.



The set-up is more nearly idiot proof, just as with a v-brake. But they would be worse in every other way.



When my cantilever brakes are adjusted to my liking they stop great. In my opinion most of these posts about people hating their brakes comes from people who for, whatever reason, dont have their brakes properly set up, or are you using some terrible stock pads.


Yes.

Assuming the OP is using reasonable pads, he needs to

- Reduce the rim clearance by moving the pads in (unless he is riding in heavy mud)

- Re-set the brakes with the yoke much lower - say at the bottom of the fork. I'd add a cable catcher for safety.

- Consult Sheldon Brown's pages re cable path and maintenance.


See http://www.bikeforums.net/showthread.php?t=580124

These two tweaks will greatly increase mechanical advantage. Total braking power will be the same, but it will be easier to apply.




Disc brakes, which add weight, but have clear advantages in stopping power, especially in cross races, are the more arguable position, in my opinion.

I thought discs were only rarely allowed in US races?

I thought discs were only rarely allowed in US races?

They are not uci legal, but you might be able to use them in countries that do not have all of the uci restrictions, like USA cycling

If you're not competitively racing, there are few good arguments against discs. Discs give better power, linear response, clear mud and moisture better...what's not to like?

I agree 100%. The only reason I didn't buy the disk version of the Lemond last year was because of stupid UCI rules of which I race maybe 2 times a year in.

I agree 100%. The only reason I didn't buy the disk version of the Lemond last year was because of stupid UCI rules of which I race maybe 2 times a year in.

I wonder if they even care in the lower cats at UCI races

I did Tour of Gila and they measured all of the P,1 bikes for the time trial, but not for any other categories

wonder if the same thing happens at UCI cross races in the amateur categories