Explanations
Effective inner diameter of the rim
The effective inner diameter of the rim is measured from the point where the spoke nipple heads rest in the rim bed. When measuring manually, you should add about 3 mm to the measured inner diameter. If you have the exact technical data from the manufacturer, specify the "Effective Rim Diameter" (ERD).
Bolt circle diameter
The bolt circle diameter of the hub flange describes the diameter of the circle in which the spoke holes are arranged in the hub flange. In hubs for disc brakes, the diameters can be different on each side. This is also called a half hub .
Distance hub center to flange
This distance indicates the distance from the centerline of the hub flange to the center of the wheel.
For symmetrical hubs, this corresponds exactly to half the distance between the two hub flanges.
For asymmetric hubs, such as cassette hubs or disc brake front hubs, the rims are slightly offset from the hub. Therefore, you must use different spoke lengths for each side and enter the corresponding values for "left" and "right".
Number of spokes
Here you enter the total number of spokes for the wheel. For example, 36 spokes if the hub has 16 spoke holes on each side.
