I hope someone can shed some light on this problem. I have a 2003 pinarello prince with campy 10 record group. The problem i am having is that when i am in top gear (big front small rear) and stand up to sprint the chain slips very bad. This problem caused me to go down very hard about 5 weeks ago. I broke my back in 2 places and my pelvis durring this wreck. I took the bike to the shop where they kept it for a month. I picked it up today with a clean bill of health. I rode it for about 25 miles and stood to sprint and the same thing happened again. This time i did not hurt myself like before but needless to say i am quite upset about this. I have noticed that both times the chain was off when i picked up the bike. I dont know if this is a component problem or frame problem. I am large at 6'3" tall and 200 lbs. I know i put out a good bit of power in a sprint. Is this problem possiably caused by the rear stays possiably shifting to the drive side due to flex in the stays? The bike does have quite a bit of mileage on it. I have lost confidence in the bike shops around dealing with the problem. any insight would help. Oh the chain and rear casette have 600 miles on them and were replaced together. thanks