Cannondale BB30 HollowGram Spindle Mountain 137mm KP308/The Cannondale BB30 Hollowgram Spindle 137mm is compatible with Hollowgram SI, and Cannondale Si crank arms on 73mm and 83mm wide mountain bottom bracket shells. Weighs only 106g. Includes spindle only, spacers sold separately as KP484.884603559598