The BB30 bottom bracket system uses a 68mm (road) or 73mm (mtb) wide shell and a 30mm diameter crank spindle. The frame's bottom bracket shell itself is not threaded; instead the bearings press directly into the frame. BB30 frame shell inner diameter is 42mm, has two bearing retaining clips and two 6806 bearings pressed directly in the shell. The BB30 system uses thin spacers and/or a wave washer between the bearings and the crank arms to take up any slack and micro-adjust the chainline of the crank.