This has come up here and on the framebuilders, so I thought I would post with a title that is easily searchable.

I just set up a 26" cruiser with U brakes, using an Odyssey Evo brake and a high-volume 2.1" tire for the setup. Measurement shows 318.2 mm between the axle center (slammed) and the centerline of the boss. On an old Diamondback Apex that had roller-cam brakes, that dimension is 316.2 mm. The distance I used on a 20" street bike with a Primo E-brake and 20" street tire for the setup is 233.5 mm.

Every brake is different for tire clearance, so a live setup is still your best bet.

jn

"Thursday"