Hi, I just built my bike and I'm having difficulty with the rear derailleur jumping, when I have it on the stand it stays on the cog it supposed to be on but when I head out on the trail it jumps around. It jumps on the larger cogs only. I'm wondering if I need to shorten the chain. Can anyone please advise a fix on this. I've tried dialing in the correct position but it still jumps. It's totally ruining my ride. Tks.
Klein Palomino
XTR cassette
Klein Palomino
XTR cassette