So I recently sold a bike to a fella and it does something weird. While shifting from the middle chainring to the big one sometimes the chain just skates around between the chainrings and often just gets stuck. It's a triple and it doesn't happen between the middle and small one. I fiddled with it myself and adjusted the front derailleur to the best of my ability and it still did it so I took it to a shop. He started adjusting it and quickly broke the clamp so he replaced the derailleur and adjusted it. It still sucks the chain between the chainrings.



What could it be? The limit screws are adjusted properly so it doesn't fall off to the in/outside.