I have a Santa Cruz Highball with (new) SRAM 2x10 X9, and the chain jumps off of the crank ring when coasting over rough terrain. The result is disastrous when coasting into a dip, then getting out of the saddle to pedal up the other side, and the crank spins out from under me because the chain is not engaged on the crank ring. It doesn’t seem to matter what gear it is in, although I only use the small ring for long or steep climbs in the saddle, so who knows. Also, if I’m riding hard and fast, of course I’m in the smaller half of the cassette, so that’s going to be where it happens. It is not dropping down to the inside, so a chain keeper is not the answer. In fact, it doesn’t necessarily even jump all the way down to the small ring. It’s just disengaged. The front derailleur has been meticulously adjusted by two different professional mechanics. The chain length has also been confirmed by both of them, and it stretches the rear derailleur nearly to its limit when in the big ring/big cog combo. The last mechanic called both SRAM and Santa Cruz to confirm that the drive line and all other aspects of the setup were correct. Any other thoughts?