Birzman Chain Keeper - New Race Fit It’s the upper pulley that

It’s the upper pulley that moves the chain left and right enabling gear change

Thermo-welded Seams

Inch-size: 20 x 1

Magnetic tool that assists internal routing by guiding adapters through the frame

Birzman Chain Keeper - New Race Fit It’s the upper pulley thatProduct Description A Chain Keeper (dummy hub) compatible with both QR and 12 mm thru axle dropouts without switching of parts or adapters. Featuring a free spinning and side shifting pulley wheel, allowing shifting of the derailleur and a high polymer spacer providing abrasion protection against dropout surfaces, this is a quick and easy tool to have on hand for routine cleaning and maintenance work. Specifications: Material : CNC machined aluminium