Problem-solvers Problem Solvers Bushnell Eccentric Lightweight Adapter For BSA Bottom Brackets – 68 X 54 Mm – Black

​The Problem Solvers Bushnell adapters feature eccentric bottom bracket shells to provide chain tension adjustment on Tandem and dedicated Singlespeed bikes. This tried-and-true design is easy to install and fine-tune to your ideal placement. It holds English threaded bottom bracket cups (BSA). 

The Eccentric Lightweight version features additional machining and drilling of the aluminium body to reduce weight, but still maintains enough surface area friction for a secure grip. The adapter fits bottom brackets shells with an inner diameter of 53.8 to 54 mm and accommodates standard BSA bottom bracket cups (1.37 x 24 TPI). The Eccentric Bottom Bracket (EBB) may be used on bicycles designed for ASTM category 3.