Originally Posted by
Lmuir
Yeah, unfortunately I bought the wheel used (before having it rebuilt, trued, etc) and I don't know what the spokes are. They are round (not aero) and they look pretty thick, but I don't know really.
It seems like it rubs every time I hit ~1000w, so it will only be one or two times per race (or maybe none at all if I'm not in contention for any sprints/prims) I'm not really too worried about the .005 seconds I'm going to lose in a sprint, but having my bike functioning at 100% helps keep my mind clear and free of distractions. I guess this issue is really common, so I'm not going to lose any sleep over it, just trying to learn.
Thanks
OK, assuming all is OK, and it's just flex, there are two sources. Lean flex because the bike is tilted when sprinting putting side loads into the system, and chain load flex because the chain is pulling one side of the rear forward with great force (minimum 2x the pedal load).
You can test for both. Check lean flex by leaning the bike, and putting root pressure directly on the BB or chainstay. Do this from both sides and observe. Chain flex is tested by putting the bike along a wall in a corner with the front wheel against the other wall. Mount the bike and set the pedal at 3 o'clock and try to ride through the wall (hopefully you won't be able to). You'll need a friend to observe for flex at the brake.
As I said, some flex is normal, and more at high loads or when the bike is off plumb is expected. The testing is more for your reassurance than anything, but may show an actual problem, such as a cracked chainstay.