stevage

I don't race cyclocross, but I ride a Specialized Tricross Sport, which recently took an unexpected[1] trip through some extremely heavy mud, that was like clay and sand mixed with water. The mud was so thick that it clagged up in huge clumps around the cantis, around the cranks, and even jammed between the rear wheel seat tube. It got so bad I could barely turn the wheels against the force of all the mud.

My buddy, on a Giant MTB with disk brakes, was fine.

What I'm wondering is, is aren't cyclocross bikes supposed to be designed for good mud clearance? Why don't they use disk brakes, considering they're apparently far superior in these kinds of conditions? Or is it just that the Tricross Sport isn't really a true "cyclocross" bike?

I'm not complaining, as I certainly have no intention of riding in those kinds of conditions again if I can help it, I'm just curious to understand the design of cyclocross bikes a bit better.

Steve
[1] See https://xkcd.com/geohashing

M_S

Pit bikes.

The Tricross has great mud clearance.

Also, cross courses often have water you ride through that sort of clears the mud off (a bit). Also, sometimes you're just better off carrying the bike and running. Part of the sport.

In terms of the disc brake thing, I aint touching that one with a ten foot pole. Nuh-uh.

dirtyphotons

the short answer is that disc brakes are illegal according to the major international sanctioning body, uci.

the long answer can be obtained by searching this forum for that very question.

flargle

A cross bike with cantis has better mud clearance than a road bike with calipers, but not as good as a mountain bike with disc brakes.

Horses for courses. Pretty simple, that.

flargle

The UCI rule is irrelevant for the vast majority of us, because very few of us actually race in UCI-sanctioned events. There is, however, a trickle-down effect that has probably slowed the adoption of discs. Nevertheless, a few mass-producers (Lemond, Cannondale, now Salsa) have gone ahead and produced race-worthy disc-equipped cross bikes.

There are three valid arguments in favor of cantis for a race bike, namely:
- lighter weight
- disc brakes are "overkill" for the vast majority of cross races (no sustained descents, for example)
- wheel changes slower with discs

There are also many irrelevant, primarily theological arguments against disc brakes.

cardstock

god says disc brakes are evil

rbiked

the amount of weight difference between disc brakes and traditional brakes is not that much... the Avid BB7 disc brakes only weigh 300grams... that is nothing and isn't going to slow you down considering it's only a fraction of a percent of your overall weight.

disc brakes were outlawed by the UCI due to their clear advantage, Disc brakes perform equally if not better in all conditions including water, mud and snow. This is due to their position closer to the hub and away from the ground and possible contaminants like wate. The pads are usually made from metal sinters or an organic compound instead of rubber. Water acts as a lubricant to rubber but not metal, therefore disc brakes maintain their stopping power in wet and muddy conditions.

changing a wheel with disc brakes actually takes time.. you don't have to touch the brakes to remove the wheel, the discs slide in and out of the caliper without any need to touch them while traditional cantilevered brakes require you to disconnect and reconnect the cables.

d2p

thats why bike changes are allowed in cyclocross.

flargle

I think most of your points are valid, but not this one. The below article puts it pretty clearly. (Emphasis mine.)

https://www.dirtragmag.com/web/news-article.php?ID=170

When asked why the UCI had disallowed disc brakes in cyclocross, Shawn Farrell, the USA Cycling Technical Director responded, "It isn't so much that the UCI has disallowed disc brakes as it is that they have not approved them yet. Our rules system is based on freedom of choice unless someone tells you you cannot do something. The UCI system is not the same. Any new piece of equipment is automatically disallowed until it is approved by them. That is a subtle distinction, but one that is important to understanding this situation with disc brakes.”

[...]

For others, the fall-back makes sense. “Disc brakes are unnecessary for Elite-level cyclocross races. Cantilever brakes keep the bike as simple as possible. Also, by adding disc brakes, you have to overbuild the fork and frame, which is where a lot of the necessary compliance comes from. At last year’s Napa Finals I saw probably three disc brake-equipped bikes. I just don’t see the need for disc brakes on cyclocross bikes.”

rbiked

sorry if i passed any misinformation with that quote, i was quoting the the Avid bb7 info page. i have not researched the UCI or the issue directly.

https://www.sram.com/en/avid/mechanic...es/bb7road.php

stevage

>Also, cross courses often have water you ride through that sort of clears the mud off (a bit). Also, sometimes you're just better off carrying the bike and running. Part of the sport.

In this case, neither would have worked. I tried riding through lots of water for that reason but the mud was too gluey and wasn't even slightly affected. And running on the slippery mud would have been impossible...very hard to even walk up the hill.

I ended up dunking my bike in a lake for 10 minutes to try and get the mud off but was only half successful.

Steve