In the interest of more thoroughly investigating crankset and chainstay clearance, BikeCAD version 21 accounts for the chainring mounting surface and bolt heads that can be a cause of interference at the front end of the chainstays. BikeCAD dimensions J4, K4, J5 and K5 correlate to dimensions X4, Y4, X5 and Y5 in this drawing issued by Shimano. To account for other dimensions in this drawing, BikeCAD now features the option to locate chainrings by the distance from the centerline of the frame to the inner surface of the chainring using dimension J3 as opposed to the distance to the middle of the chainring W3. Also instead of specifying the thickness of the crank arm E, we now have the option to specify the distance from the centerline of the frame to the inner surface of the crank arm with dimension W4. Finally, while BikeCAD used to collect a dimension for the diameter of the crank arm at the pedal end of the crank, we can now recognize that crank arms aren't always perfectly round at the ends and therefore, not only do we collect dimension C for the width of the crank arm, but also dimension P to define how far the crank arm extends beyond the center of the pedal spindle. The standard crank library now includes all these specs for 11 and 12 speed versions of the Shimano Dura-Ace, GRX and Ultegra cranksets.
Bicycle Design Software
