Shimano XT Disc Brake Ques.

[jben415]

I just bought a new mountain bike and it came with XT Disc Brakes. This is my first bike with Disc brakes and I have a question - the space b/t the pads and the rotor is extremely small and I understand that this is normal. However, the brakes are rubbing (slightly) on the rotor. Can this be adjusted and if so, how?

Can anyone recomend a competent shop near Bethesda...competent being the key word.

Thanks...hope to meet some of you on the trails in the near future.

Ben

[drevil]

Well, one thing you might want to try is taking it back to the shop you purchased it from. Shops usually have a limited adjustment period where they'll fine tune your bike as it breaks in.

If you don't want to do that, you can read the FAQ (http://www.mtbr.com/techtalks/brakes/brakesfaq.shtml#operation) on MTBR's website pertaining to brakes and try to fix it yourself. Sounds to me like a slightly warped rotor, which is not uncommon, and relatively easy to fix. It involves an adjustable wrench and slight tweaking with the rotor.

If you just want to take it to a shop, I've heard the City Bikes shop in Bethesda/Chevy Chase does good work.

[IFBikeMD]

I've got Hayes disk brakes and have grown accustomed to some infrequent rubbing that comes and goes. Check the roter and also check to make sure the wheel is completely seated. I've played with the roter before only to discover that the wheel wasn't 100% in.

I've tried most of the shops in the Bethesda, Chevy Chase, Rockville area. City Bikes is the only one that seems to care that we love our bikes and are obsessed with riding. They fix most things while you wait.

- James

[td_va]

I've got Avid disk brakes, so this might not apply. But, my brakes have a round knob on each side of the caliper. Turning them adjusts the tolerance for their corresponding brake pad. I have to adjust them occasionally to prevent contact (squeaking) when I'm not using the brakes.

Hope this helps,
TD

[DaveG]

In addition:

The Shimano disc brakes tend to run VERY close to the rotors. I usually have a slight rub (i.e. zing noise) from my rotors because honestly I can't be bothered to tweak them very often.

I would try truing them by hand first before using an adjustable wrench. You can really wreak havoc w/ an adjustable wrench if you don't know what you're doing (trust me on this, my advice comes from experience :) )

What I usually do is grab a clean cloth to cover my fingers (never touch the rotors w/ bare hands; it will get oil on the rotors), spin the wheel to find the low/high spots in the rotor, and tweak them appropriately. I usually just give it a push opposite the direction it's rubbing.

This takes longer, but it's less prone to screwing things up.

If you find that it's rubbing consistently on one side or the other, then I'd look at two things:

1) I find that QR tension makes a big difference. If the brake is centered correctly I can usually get the front to run rub free by popping the wheel free, rotating the axle and re-installing. Sometimes is takes a few tries. For some reason I haven't had as much luck w/ the rear.

2) It's possible that the brakes weren't setup/centered correctly when the bike was assembled. I think the new XT calipers use IS adapters, so you could probably loosen the fixing bolts, apply the brakes to center them and then snug up the bolts.

Since it's a new bike, I'd suggest taking it back to the shop. Ask them if you can watch while they fix it so you can see if it's something you feel comfortable with doing yourself.

Good luck.

Dave