It's easy to do a roll out.
1. Put the bike on a flat surface.
2. Make a chalk mark on the ground and the tyre where the tyre contacts the ground. Do it in the middle of the contact patch.
3. Roll the bike forward until the chalk mark on the tyre is again in the centre of the ground contact patch, but one wheel revolution further forward.
4 Make another mark on the ground at the centre of the contact patch.
5. Measure the distance between the two marks on the ground.
Job done. Any wheel. Any tyre. No tables needed. Just measure and mark carefully and use a thin chalk to get accurate marks.
If you have no chalk, just use the tyre valve as the reference point on the wheel and place a matchstick on the ground at either end of the wheel roll out.
Last edited by EvilV; 06-11-09 at 01:46 AM.