Originally Posted by
jsdavis
Exactly this...I think my rotor is slightly warped because it scrubs once per rotation and only starts after I start to descend the hill from work, about 300 ft in 1/2 mi with a stop sign every 400-500 ft. It will last the rest of the ride home, but I won't hear it on the way to work the next morning. I suspect the rotor is expanding slightly just enough to cause scrubbing. My ride is all urban so I'm braking at least once every 300 ft so probably the brakes don't have sufficient time to cool and contract between stops. Just a guess though.
Rather than any kind of rotor expansion (it'd have to expand
a lot), I'd suspect vibration. I have a rotor that behaves similarly. Mine is a 203mm rotor (a giant thing) that may twist in the wind a little or just vibrate due to the road. It's constantly making the same noise movie makers use for a sword being drawn from a scabbard.
Originally Posted by
apollored
Having had only rim brakes on all the bikes I've had, I am interested if and when I get a new bike on having one with disc brakes.
Are they better than rim brakes as I have read that they dont last very long out of the LBS and can still squeal like mad if they arent set up properly.
Which are best?
Thanks
mechBgon summed it up nicely. I'll add that braking
techique goes much further than the braking
mechanism, even in the worst conditions. I have discs on two bikes and rims on 5. They all stop. They all stop very well. I've mountain biked...not mild stuff either...for years and years without discs and never had a time when I wished that the brakes worked better. I did a 1200 mile loaded tour in Appalachia this spring on a touring bike equipped with cantilevers including one 20 mile downhill run with speeds up to 50 mph in a driving rain and never lacked for braking ability.
Learn
how to brake and the
kind of brake becomes much less important.