Oct 23, · The bottom bracket connects the crankset to the frame and incorporates bearings which allow the cranks to freely spin. It features either a spindle or capacity to incorporate a spindle to which the crank arms, chainrings and pedals are eazye.info: Christian Woodcock.
The bottom bracket or ‘BB’ is the engine room of your bike’s chainset and one of the two most important bearings on your machine (the other being the headset).
Mar 23, · The 68mm and 73mm dimension measure the width of the bottom bracket on the frame of the bike with no BB installed, simply the width of the shell. Most road bikes that use a threaded bottom bracket measure 68mm wide and most cross country/trail mountain bikes measure 73mm.
Bottom Bracket Bushing Set: Includes ten precision-machined bushings in 6 sizes covering installation of all road, mountain, and bmx press-fit bottom brackets cups and bearings, plus a BB Bushing Spacer for enhanced flexibility, speed, and alignment.