Shimano bb 5500 105 bottom bracket splined bottom bracket designed for use with shimano road octalink crankset oversize bb spindle large 22 mm diameter chrome moly hollow pipe billet spindle reduces weight increases strength and rigidity octalink splined axlecrank arm interface results in a more rigid crank assembly compared to square tapered spindle maintenance free sealed cartridge design prevents corrosion and is easy to install aluminium adapter average weight 250 g