Shimano Shimano ES51 Octalink bottom bracket

Oversize BB spindle - large 22 mm diameter hollow pipe billet spindle reduces weight, increases strength and rigidity. Octalink splined axle/crank arm interface -results in 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