Broken Rear Deraillier

Wembley1

I bought a new Lemond Alpe de' Hueze one month ago. It has a Shimano Ultegra rear deraillier. Never wrecked nor dropped etc. This AM it started shifting strangely and making noise. Just as I was starting home the rear deraillier mounting arm snapped. I wondered how strong they were. However, I never thought one would jsut break in half without some kind of abuse.

My dealer will replace under warranty. However, my search on the web indicates that the metal is not brittle so it will bend rather than break. Has this ever occcured to anyone else nad if so why??? I am sure that it can break if hit hard enough, but not just to go on its own within one month of purchase.

gclark8

I have seen this once before on a brand new bike, ride 1, the pin came out of the chain and bent the RD cage and broke the body. Make sure they fit a new chain with the new RD.

hd reynolds

I bought a new Lemond Alpe de' Hueze one month ago. It has a Shimano Ultegra rear deraillier. Never wrecked nor dropped etc. This AM it started shifting strangely and making noise. Just as I was starting home the rear deraillier mounting arm snapped. I wondered how strong they were. However, I never thought one would jsut break in half without some kind of abuse.

My dealer will replace under warranty. However, my search on the web indicates that the metal is not brittle so it will bend rather than break. Has this ever occcured to anyone else nad if so why??? I am sure that it can break if hit hard enough, but not just to go on its own within one month of purchase.

Ultegra aluminum is forged differently (and more inexpensivley) than DA resulting in a more inferior grade than the later. That rear derailleur was probably doomed at the onset because unless shimano x-rays its aluminum parts one-by-one for metal defects the metal properties of that part will not be detected until it breaks prematurely. Having said that, you probably got a bad egg out of thousands of ultegra rear derailleurs.

For perspective, DA parts are structurally more robust because the aluminum is worked differently. Unfortunately this also adds to the cost.