alignment could be a factor here, too. If the cage is grabbing the chain way far back on the cage, that puts a very big moment at the cracked corners. This load would be minimized by having the derailleur aligned to contact the chain as far forward on the cage as possible.
On Monday, August 18, 2014 10:41:10 AM UTC-5, Ron Mc wrote: > > a derailleur cage is a C-shaped channel. Pulling the chain in either > direction puts opening loads on the sides and especially inside corners of > the channel. You would hope it's not going to fatigue, but that's the > failure mode, slow crack growth. > > On Monday, August 18, 2014 9:58:11 AM UTC-5, lungimsam wrote: >> >> That's bizarre. You would think a derailer wouldn't break like that at >> that place because any pressure/ movement would make the derailer move, not >> resist and break. >> Does the chain sometimes jam between the big ring and the derailer when >> shifting into the large ring? That's the only thing I can think of that >> would stress the cage to make it break like that. But I am no expert. Chain >> suck maybe? Old age? >> Mine jams sometimes. Operator error I think. Shifting too far too fast. > > -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch. For more options, visit https://groups.google.com/d/optout.
