Bent front mech

edited April 2012 in Workshop
A friend's front mech was prized open slightly by his chain when making a gear change from the small chain ring onto the big chain ring. As a result he had a new front mech fitted by his lbs and all has been sweet as a nut for the three subsequent rides. Tonight however, the same thing has happened again, the mech has been prized open and the chain totally jammed on him! The chain isn't worn, neither are the chain rings and he isn't aggressive when changing gear. I've advised him to go back to his lbs as even if the mech isn't faulty, they should have checked that all was ok and that the bike was safe to ride. Anyone come across this before?


  • Twostage
    Twostage Posts: 987
    Sort of, I've had something similar. Was the cage bent open at both sides ? If so it might not be the chain but the dr catching on the chain ring and being pushed into itself. The cure is to lift the dr up a bit. The problem is either it being too low in the first place or it sagging due to wear although this won't be the problem if it is new.
    You should be able to bend the cage back into shape so it is usable I would have thought. And yes the lbs should have made sure there was enough clearance.