During a race this past w/e ( Laramie Enduro!) when I shifted up from the granny to the middle, the bottom part of the chain would get sucked in between the rings & chainstay. Happened twice so I had to get off & pull it out. Then I could tell the dreaded sound & slow my pedalling to prevent the suck. Sometimes it was going to happen shifting from middle to granny too. My chanstay is scratched but not too bad. Is this from a worn chain ring (s)? Chain & casette are new.
THX
THX