The Problem Solvers Bushnell Eccentric Bottom Bracket is the industry leading design for chain tension adjustment on tandem and dedicated single speed bikes equipped with eccentric bottom bracket shells. The classic version features full-body, aluminum construction across the shell for maximum surface area friction and additional value. The Bushnell Fat Bike Eccentric Bottom Bracket is designed for the 100mm shells in most fat bikes. - Accepts English threaded bottom bracket cups - Classic, full-body design - Diameter of part - 2.118 inches (53.78mm) - Fits BB shells from 53.8 ~ 54mm I.D. without shim - Fits BB shells up to 100mm width