I was taking my bike for a test ride after fitting a new to me Shimano RSX groupset, and when I shifted into my lowest gear in the cassette, the chain dropped behind the cassette and ripped the derailleur out of the hanger (destroying the threads) and launched it into the rear wheeI’s spokes and breaking them.
The only damage is a single broken spoke and the derailleur end stop being flipped. Any ideas on how to fix this? Thanks!
by Atrick07
1 Comment
Your pictures depict the B-screw, which had zero impact on your chain dropping. The purpose of that screw is to adjust chain tension and to ensure the pulley wheels don’t contact the cogs.
>the chain dropped behind the cassette
You did not properly set the L-screw. Because of this, your chain was allowed to go inboard past the largest/lowest cog and into your spokes. e.g. google ” Park Tools video rear derailleur installation.”
Next time, properly set the L-limit screw, H-limit screw, and the B-screw. Plenty of videos out there walking you through the entire process.