I bought a carbon 29er back in March and have been plagued by the chain jumping off the big ring when hammering along on rough terrain.
Could be down to the fact that the SRAM X0 front mech is about 4mm above the big ring as the Direct Mount fitting won’t allow it to go any lower.
LBS tried to fix it and even a shorter chain did not help.
I was at Afan on Saturday and the chain jumped and jammed coming down the steps on Darkside so I couldn’t pedal or rotate the cranks at all. Fixed itself a few seconds later but a bit scary.
I popped in to Skyline cycles and they agreed that the mech should be a bit lower but it was on the lower limit of the direct mount. They had a DM Shimano XT so I asked if they could fit it as it looked like it would mount lower. 20 minutes later I was off again.
New XT mech shifts way better, doesn’t have the stupid cut out on the side plate where I suspect the chain jumps out of.
And the chain didn’t jump once for the rest of saturday and sunday. Especially down the the Wall singletrack with loads of braking bumps.
Kudos to Skyline and Mr Shimano.