race wheel question

[dave.delano]

I have Tufos on my Zipp wheels, 303 front & 404 rear. The set-up is new this year and has raced 250-odd miles. Sometimes, when on a really smooth surface, I have noticed a slight bump in the rear. Any ideas where to start the investigation?

[Serotta PETE]

Sounds like the rear tire could be irregular. Easiet way to find out is to switch out the rear tire. (yep a pain). It should go away, unless the rim has a flat spot. THe one time that I had the problem, it was the tire.

Pete

[Too Tall]

Put a chalk mark on the bump and yank the tire off. Mount it dry on a clean tub wheel, pump it up, get it straight and spin it on a truing stand. Bump still there? Prolly a bad tire otherwise clean up the old glue and remount it and the problem should go away.

If you mounted the tire crooked it will cause the bump.

LAST! if your "bump" is happening only at high speed. The cause can be an unbalanced wheel...which is real easy to do with Tufos if you use a heavy valve extension. Bean there dun dat. Solution is to use the shortest aluminum extension possible or (GASP) stick on weights.