Splined bottom bracket for use with Shimano Octalink chainsets Oversize BB spindle - large 22 mm diameter hollow pipe billet spindle reduces weight, increases strength and rigidity Octalink splined axle/crank arm interface -resultsin more rigid crank assembly compared to square tapered spindle ES51 has anti-corrosion treatment inside hollow spindle Sealed cartridge assembly - maintenance-free sealed cartridge keeps out dirt, mud and water Cartridge design allows easy installation without adjustment Aluminium adapter Average weight 262 grams