Eccentric Bottom Bracket Adapter - 46mm & 51.3mm

Optimize your mid-drive motor conversion with our Eccentric Bottom Bracket Adapters, designed for a precise and secure fit on a wide range of frames. The eccentric shape reduces bottom bracket wall thickness, ensuring your mid-drive motor can slide in without obstruction, which standard adapters may block.

The 46mm Eccentric Adapter fits frames with a 46mm inner diameter (I.D.), such as those that accept PF30 bottom brackets and similar sizes.

The 51.3mm (American/Ashtabula) Eccentric Adapter is perfect for frames originally designed for one-piece cranks, typically with a 51.3mm I.D. bottom bracket shell.

A small amount of thread-lock adhesive or sealant is recommended to prevent rotation. While movement is minimal once the mid-drive is installed, this extra step ensures long-term stability.

 

Whether you are converting a classic cruiser, BMX, or modern frame with a PF30 bottom bracket, these adapters provide a precise fit, hassle-free installation, and optimal compatibility for your mid-drive setup.