This not being an issue for MTB stems from two apparent reasons:
-most people use hydraulics for mtb
-it would largely be irresponsible to mtb on trails that were consistently torn up the way wet/mudbog cx races are. Even on race days (short track excluded) you likely only do several loops on any given XC course. At least in New England, there are people consistently on the course from 8am until 4pm, many of which cover far more than 10 laps between race+preride.
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Disc brakes cyclocross bike observation.
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The complaints I hear about discs on CX bikes is the modulation. Apparently not very good on most mechanical systems.
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nordicX- Although mtb races are fewer laps they are longer by both distance and duration.
Jam Econo -
we did an mtb race here in florida where the trail was extremely wet but not muddy. lots of sand though. there were lots of people buying new disk rotors due to the pads being used up. one thing with cx, can't they change pads when they do a bike swap in the pits? or is that too much to undertake in the time allotted?
If you are not hallucinating, you are not trying hard enough -
Well Skinny, that would be a very fast job as most cross races I have done are 7-12 min laps. On a super muddy bike, minimal workspace, limited tools I doubt if I could change pads that fast. Mine are usually couple beers and 20 minutes in my clean, well lit work area , on the stand with the pads and tools ready to go. I would suppose a whizbang mechanic could, I am not that guy.
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CB2, I think the point nordic was making was that the trail of a MTB course isn't traveled many hundreds of times at one event. By the end of the day at a CX event, the muddiest parts of the trail are a place only a pig could love.
Just for some crude numbers: say 5 races, 40 starters average, 45 minute races, 7 minute laps. 45/7 x 40 x 5 = 1286 laps ridden racing. Say times 1.25 to include warmups. 1600 laps. If the first lap was muddy, lap #1600 will be require little curly tails and cute hooves.
And to add to velojo's post: It's 40 degrees, rainy and windy. Those fingers aren't working so fast!
Ben
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It's unlikely you'd need to actually change pads. You'd need to dial in the caliper adjustment. The problems with that are that a) you absolutely need two bikes which the vast majority don't have and b) you need to have a dedicated competent person working the pit for you. The overwhelming majority of amateur riders self-pit. Our elite races might have three people in the pits for 30 people.
For disclosure purposes, I am a partner in November Bicycles. This fact probably colors everything I say. I'm clearly not to be trusted. -
I have done more than one xc off road race where I had to dial out the barrel adjuster for the rim brakes. I have dialled up in cross races too. I recall one race on Cypress where it was especially wet and I wore out the rear u brakes pads to the metal in the 2.5 hour race. Deep sandy gravel along a steep downhill guaranteed brake wear. Not surprising at all that a mechanical disc could see enough pad wear that it requires dialling out. That's why hydraulic brakes are far superior. Or one reason anyway.
Lance who?? -
79mooney, you are a funny guy. I have had that exact thought at every PDX cross race I have done. 1500 riders say 10 laps , two wheels on all the bikes cept the unis some 20- 30 thousand wheels have hit that off camber turn before the last guy in the last race. Oh my.
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velojo, do you remember last year's CX at Alpenrose when it started raining before the woman's start. Casualties on the off camber climb to the track were higher than 90%. (That includes those who chose to "run".)
Ben
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I wasn't there last year, but have done that race a few times. When it is raining getting up to the track is tricky indeed, turning on to the track is a slow fall on slick concrete. Charging to that steep banked wall going clockwise, muddy and wet, will tighten the pucker factor way up there. The Raceway and Alpenrose are my two favorites in PDX.
When they first built Alpenrose, I got there lost finding the place. Unpacked my stuff, warmed up for about 3 minutes on the rollers and tried to do a kilo for time. The only track I had been on prior was Northbrook that looks flat compared to the dairy track. Needless to say it was not pretty. I have been in love with your town since Strawberry was the bike to have in the PNW and craft beer was not even thought of. Drank a lot of Lucky Lager , Oly, and Rainier in your town back in those days.
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The vast majority of disk brakes used today use sintered metallic pads working against hardened, heat-treated rotors. It normally takes a ‘ton more’ hard braking in muddy gritty conditions than one cross race to put any appreciable wear it this type of set-up. In addition to the various metallic pads, there are also some soft resin pads available. Resin pads sometimes paired with softer non-hardened rotors have the advantage of an almost instant bed in period and quiet running. In tight twisty slow speed conditions these pads provide great friction and pinpoint braking. This is a dry weather set up only, as wet conditions do wear the pads quickly.
The OP omits to tell us what make or model of brakes in question, so we are left to guess at this improbable result. Often if the caliper and lever are not made for each other it can take more cable pull than ideal. This can work ok, but a little wear or bed-in can use up all the available cable pull (levers hitting the bars).
The OP seems to be a fatuous fellow with the proverbial chip-on-shoulder, so I suggest not worrying too much about his constant chicken little-ism.
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+1 AF. That makes sense of my contrary experience with BB7s in Pisgah National forest before I switched to hydraulics, where it's almost always wet, and a mud granite gravel slurry bathes the brakes. I descended trails like Black Mountain many times with virtually no brake pad wear. And the brakes worked great. I've raced cross in heavy mud back in the day, and for sure the braking loads and wear potential were less than in Pisgah.
It's got to be the pads and rotors.
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