A fried of mine rides a 2004 Giant Carbon fiber bike with 10 speed Dura Ace. He has thrown his chain three times over the past week during accelerations. In all three cases he was not changing gears, but he threw his chain off of the big chainring while accelerating. Once was up a hill, once was on a flat, and once was on a slight downhill. All three times he was going all out, which probably means about 700 watts of output at a cadence of around 90 RPM. (He is nationally competitive.)
He did not crash any of the times but it was not fun. He did replace his chain after the first time he lost it. The second two times occurred yesterday on the same ride.
Some of the guys I road with made some random comments that other people had been having the same problems with 10 speed Dura Ace. Has anyone else heard of problems with 10-speed Dura Ace and chain losses? (Or Giant carbon fiber bikes and chain losses?)
I should add that I can do the exact same thing with my 10 speed Campy Record Cannondale— If I accelerate all out from a dead stop in my 53x11, I will throw the chain every time. I basically flex the BB so much that the angle becomes acute enough to cause the chain to dislodge. However, the only time I want to do this is in certain training sessions, and it’s never impacted me in normal riding.
-Marc