Dropout spacing

In BikeCAD, it is important to specify the rear dropout spacing. With quick release dropouts, the rear dropout spacing is the distance between the inner surfaces of the dropouts. These surfaces are used as a reference for defining the ends of the chain stays and seat stays. The ends of the chain stays are offset by dimension Cz from this surface. The ends of the seat stays are offset by dimension Sz from this surface.

With the advent of thru axle hubs, we talk about how the over locknut dimension went from 135mm for mountain bike hubs to 142mm for thru axle hubs. And while it is true that the distance between these two surfaces on a set of thru axle hubs is 142mm, there is still an inner surface of a thru axle dropout that remains 135mm from its counterpart on the other side. For consistency, we would still like to reference this surface when defining the attachment points for the chain stays and seat stays through dimensions Cz and Sz.

In BikeCAD version 20.5, we've enhanced the menu for defining rear dropout spacing to document both the over locknut dimension (or O.L.D.) and the distance between the two inner surfaces of the dropouts (or DS).

The menu still includes track, quick release road, and quick release mountain where in each case values for DS will be the same as the value for O.L.D. as well as options for standard thru axle, Boost and Super Boost spacing where the O.L.D. values will be 142, 148, and 157 respectively, but values for DS will always be 7mm less than the O.L.D.