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Discussion Starter · #1 · (Edited)
The number one cause of car disk brakes warping is by heat. It's not the heat itself that warps rotors. Bike disks are very similar to cars in how they deal with thermal expansions.

It's the cooling down from a long hot descent that warps rotors. You can prevent this by not locking up your brakes after they've become hot. Most people will warp their brakes while waiting to get back on the ski lift or while taking a mid trail 10 min break.

Imagine that the whole rotor is red hot from a 4000 vert ft run down the mountain and you sit there waiting in line for the lift. The whole rotor is going to cool down very quick except for the area where the caliper is still in contact. The caliper itself should also be very hot and will retain heat longer than the rest of the rotor.

By sitting on one spot after riding really hard you are forcing the rotor to cool off unevenly. 90% of the rotor will have lost 50% of it's heat while the portion still covered by the caliper has only lost 10% of it's heat. The portion left inside the caliper (only takes several seconds) will remain more thermally expanded than the remaining 90% that has cooled off and contracted it's thermal expansion. It's in that exact spot where your warp will show up.

Basically sitting in one spot after a hard run is what causes rotors to warp even if they haven't been touched by anything that can bend them. You want to keep the rotors spinning for a minute or two after a hard ride to prevent them from warping due to thermal inconsistancies.. Try pedaling around the lift for a minute or move your bike back and forth to spin the wheels while waiting in line.

Remember this works for cars too. Never brake hard at a stop and hold the brake. Always brake before the stop and coast slowly to a stop. Your front car brakes will last much longer.
 

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I know this, but it's still hella cool to pour water on them from your camelback and watch it get vaporized....

6" hayes and "DH descents" do not mix. They can be adaquate, but they warp when they get "red-hot" and cool..
 

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For sure!!!!

Jm. said:
I know this, but it's still hella cool to pour water on them from your camelback and watch it get vaporized....
I'm a big fan of touching the rotor to my leg. It gives you a wicked burn with cross-drilled marks! The scars are sweeeeeet..

Beau
 

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Discussion Starter · #4 ·
I've been riding on a hayes front disk for 3 months of hard use and have never noticed any warping. The rotor is still within .1mm of being true. I ride really hard on it and I do 3000ft DH runs on a frequent basis, no warping, at all. I've never locked up the disk when it's red hot, nor have I ever left the bike sitting in one spot directly after heavy braking.

I would think people who ride at ski resorts would experience brake warping more than others. I personally never ride ski resorts. My freind's and I always hike up our vertical or shuttle. One of them went up to Whistler for two days and came back with badly warped rotors. None of us have ever warped a rotor until then.
 

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BudhaGoodha said:
I've been riding on a hayes front disk for 3 months of hard use and have never noticed any warping. The rotor is still within .1mm of being true. I ride really hard on it and I do 3000ft DH runs on a frequent basis, no warping, at all. I've never locked up the disk when it's red hot, nor have I ever left the bike sitting in one spot directly after heavy braking.

I would think people who ride at ski resorts would experience brake warping more than others. I personally never ride ski resorts. My freind's and I always hike up our vertical or shuttle. One of them went up to Whistler for two days and came back with badly warped rotors. None of us have ever warped a rotor until then.
the amount of vert is almost meaningless. There's a nice 2500 descent around here off of Bill Williams mountain near Flagstaff, but the thing is that for the first couple miles it is so steep that you are "on" the brakes almost completely. You got to let go every once and a while to try and let them cool, but even that is fairly futile, they simply can not cool enough because the slope is so steep. It's runs like this that I wish I had the 8" rotor back on this bike, but it's just my trail bike. I don't have problems with the 8" hayes getting too hot, but definitely the 6"ers, I know some other places where I can do the same thing as far as get them way-too-hot, and they most definitely "warp" when that happens, in fact the rest of the way down this particular mountain they were screaming like a banshee, even though up to that point there was nothing wrong with them.
 

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Discussion Starter · #6 ·
True,

It's doesn't really matter how much vert a run is. Hard braking is hard braking. It's the steep sections with many turns and switchbacks that get my pads steaming hot. Otherwise I never use the brakes. :D

Heck, I rode a crappy Diamondback that had only a rear brake for 6 months, but never took it on anything too steep. It really depends on the rider and terrain more than vertical.
 
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