Mountain Biking - Disc Brakes

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brinks13081
02-28-06, 08:45 AM
I just got a new Stumpjumper with disc brakes. Its my first bike with disc brakes. My question is, when I turn the front wheel I can hear the brake pads and the disc rubbing a little bit. The wheel turns just fine and it doesn't seem to be slowing the wheel, is this normal?
The rubbing is normal. It may go away some once they break in.
It will go away.
It will also do that when dirt gets in them from time to time.
willtsmith_nwi
02-28-06, 11:28 AM
The rubbing is normal. It may go away some once they break in.
Well it may be normal on a poorly maintained bike. But when you do things right, there shouldn't be any rotor rub. It will slow you down a little bit.
For the original poster, the rub will not hurt anything unless it really bad. Depending on what brakes you have it may be easy or difficult to tune out. You may also try removing the wheel and re-seating it. Sometimes the spacing can get thrown off a little bit.
How to fix:
Avid BB7 - Easy Schmeezy - just adjust the dials so the pads are as close as possible without rubbing.
Other mechs - If it's rubbing on the inner pad, back it out. You may have to adjust the tension in the lever cable to get the brake to work well.
Hydro (all brands except some chepos with only one piston) - the pistons are self adjusting. If you're still getting rub, you may need to "center" the caliper over your rotor.
Bent rotor - if your rotor isn't perfectly straight it will rub every time the crooked spot comes around. Take and adjustable wrench and gently "push" the bent portion back where it is supposed to be until the rubbing goes away.
Expect rubbing to return since we are mountain bikers and hitting that rotor on anything is likely to knock it out of line again.
Seeing that you get the rubbing when you turn your front wheel, could it be that your brake cable lengths are too short and/or not routed properly. Assuming your brakes are mechanicals, you may effectively be slightly engaging your brakes everytime you turn. I wouldn't call it normal brake rub since it only happens when you turn.
crosseduprr600
02-28-06, 07:37 PM
i currently just bought a Yavapai with front and rear brakes and my bike also has this slight rubbing in the front wheel can u adjust the brakes on this model???
P.S i bought the bike from dicksporting goods so i am not sure what the put together fully or not i have already found a few loose bolts,brake levers could touch the grips and barely slow the wheels and the forks where on backwards bought the bike yesterday monday febuary 27,2006 and i have already found all this any other area's i should check ?
mtb-chop
02-28-06, 07:53 PM
i currently just bought a Yavapai with front and rear brakes and my bike also has this slight rubbing in the front wheel can u adjust the brakes on this model???
P.S i bought the bike from dicksporting goods so i am not sure what the put together fully or not i have already found a few loose bolts,brake levers could touch the grips and barely slow the wheels and the forks where on backwards bought the bike yesterday monday febuary 27,2006 and i have already found all this any other area's i should check ?
I may catch a blast for this, but who cares - with those problems, I'd check the return policy. With all those problems, you can't tell if that thing is safe to ride and from the looks of things (brakes barely engaging after a full pull to the lever) it isn't. If you don't return it, take it to a real bike shop (not Dicks) and have them go over it and correct any problems from the original poor assembly.
If you aren't too attached to the bike, I'd return it, and take the funds from that plus what you would have spent at a shop to ensure it's safe (about $50) and go to a shop and get a properly assembled bike. Your experience is a great example why people should not trust the kid in the back of Dicks with their safety.
Whatever you decide, I hope it works out for you, and you end up having a great time riding.
crosseduprr600
02-28-06, 07:57 PM
forks are fixed brakes grab with about a 1/4 pull on the lever now and i have gone over the bike about 2 times already and gonna go over 1 more time to just check the stuff and maybe catch something i over looked before
FreeRidin'
02-28-06, 08:27 PM
its fine when just means the disk is a little bent, with a little bit of hard braking the pads will get smaller the the sound will go away.
brinks13081
03-01-06, 11:44 AM
Just to be clear, this bike is brand new, just assembled and has about ten miles of road riding on it.
willtsmith_nwi
03-01-06, 08:24 PM
Just to be clear, this bike is brand new, just assembled and has about ten miles of road riding on it.
If it's brand new, you could take it to the shop and ask them to true the rotor. That should have been done before the thing left the shop. If the shop people are nice, ask them to show you how to do it. They'll be happy to show you how to fix the little things that they make no $$$ fixing.
Rotors go out of true ... period, get used to it and learn how to fix it yourself.
More expensive rotors stay straighter, longer though right?
blue_neon
03-02-06, 02:33 AM
More expensive rotors stay straighter, longer though right?
I would hope so.
willtsmith_nwi
03-02-06, 09:50 PM
More expensive rotors stay straighter, longer though right?
At the thickness of a bicycle disc rotor, they bend ... period. No amount of money will change that. A ceramic rotor would not bend, but I'm not sure that material is strong enough to stay in one piece at that thickness (they would shatter).
The most expensive rotors out there are titanium. Titanium is more "springy", it will flex farther and retain it's original shape. However, I've read accounts that they wear VERY rapidly. I'm not entirely sure about this as I've also read reports that titanium chain rings last forever.
Any metallurgists out there like to weigh in?
The most expensive rotors out there are titanium. Titanium is more "springy", it will flex farther and retain it's original shape. However, I've read accounts that they wear VERY rapidly. I'm not entirely sure about this as I've also read reports that titanium chain rings last forever.
Titanium chainrings normally are replacing aluminum chainrings, so they'll last longer. Steel chainrings should last even longer. Inexpensive disc rotors use steel for the entire rotor or at least the braking surface. Aluminum disc rotors wear out extremely quickly. Titanium rotors shouldn't last any longer than steel rotors as far as wear goes, but they may -- in theory -- resist warping better versus steel (I'm not entirely sure on that one, I'll have to look into it).
Jeez all this talk of Ti not lasting longer than steel is shattering my belief thats its the toughest most durable metal like i was lead to believe!
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