splined bottom bracket for use with Shimano Octal ink chain sets oversize BB spindle – Large 22 mm diameter hollow cold forged chrome-moly Pipe billet spindle reduces weight comma; increases strength and rigidity octal ink splined axle/crank arm interface – results in more rigid crank assembly compared to square tapered spindle sealed cartridge assembly with oversize ball Bearings – maintenance-free high Efficiency Rubber seals keep out dirt comma; mud and water cartridge design allows easy installation without adjustment.