Bottom bracket components Shimano Acera ES-300 Octalink. Large, oversized hollow spindle with a diameter of 22 mm made from cold-forged chrome-molybdenum tubing for weight reduction. The solid spindle increases the strength and stiffness of the interface between the axle and crank arm. The result is a stiffer crank compared to a square tapered spindle, which is sealed with oversized ball bearings. Maintenance-free, highly efficient rubber seals protect against dirt, mud, and water. The cartridge design allows for easy installation without adjustments.