Originally Posted by
Lars Halstrom
All great discussions. One thing I didn't state is that it happens in my lowest gear. I modified my 9 speed drivetrain to an 11-36 cassette instead of the 11-32 and a long cage Shimano Deore rear derailleur instead of the OEM Sora. So when on my 34t chainring and 36t cog, I have a lot of torque climbing. Maybe that is affecting the rear hub bearings, dropout deflection, wheel deflection and chain stay deflection adversely. The 2013 bike has over 4K miles on it. i've test ridden many other bikes with 11-32t cassettes and 50/34t chainrings with hydraulic disc brakes without any issues of drag while climbing. Maybe the best thing to do is take it to my trusted LBS and have him ride it up some hills.
How about a small experiment.
Loosen the mounting bolts and kick the caliper over a hair so it rubs slightly on one side. Tighten and ride. I'll bet 3 beers to one that you hear it more than you feel it.
Not saying that fork flex can't make a disc brake rub, just that you'd hear it if that were the case.