The rear derailleur is no different in this regard, ... or you’ll need to install a new larger derailleur cage to accommodate. ... Shimano GRX 810 rear derailleur. $140. View.

3. Finally, shift to low gear. The chain will be on the largest ring in the rear and the smallest ring in the front. Tighten the L screw until the derailleur can move only as far as the largest ...