Originally Posted by
theopowers
I have some instructions for using a standard wheel dish gauge that touches the hub and the rim at two places. It has a formula that takes the distance the non-touching point is from the rim or hub and determines approximately how many turns of the nipples will properly dish the wheel.
This suggests to me that one turn of a nipple will move a rim a standard amount to the left or right. Is this true, and does anybody know how far? Thanks!
PS does this amount vary based on rim size? e.g. 700c vs 650c?
Spokes are generally 56 tpi, so one turn of the nipple will shorten the spoke by 1/56"
How much that will move the rim sideways depends on the angle of the spoke from the central plane of the wheel.
To properly dish a rear wheel you need to start out with shorter spokes on the right than on the left, usually a 1 or 2 mm difference. Then you fine tune the dishing as you fine tune the truing.
See:
http://sheldonbrown.com/wheelbuilding
Sheldon "Not Everything Is Done By The Numbers" Brown