Shimano RX100 #RD-A551 8-speed Rear Derailleur from 1998 – Velosaloon.com
Pre-owned: Shimano RX100 (RD-A550) 7-speed short cage rear derailleur – Cycloan Education And Restorative Approaches
Shimano RX100 RD-A550 Short Cage Rear Derailleur (F85) | eBay
Vintage Shimano - RX100 rear derailleur on the vintage Shimano service bench. These are basically identical to 105 1055 apart from the polished finish. | Facebook