Sram rival cassette coming loose..
Two weeks ago I bought a brand new Cannondale CAAD9-4.. rival/force mix. About 40 miles into my first ride the cassette comes loose, chain hops off and whole thing locks up. Next morning I took the bike to where I bought it, they tightened it, apologized and sent me on my way. I asked them if the hub body and lockring looked ok, they said yes!
Flash forward about 60 miles worth of riding and I stood up to hammer and the chain jumps to an easier gear.. cassette is once again loose, just not as bad as last time.
Obviously I'm going to take it to the shop again, but should I request a new lockring at minimum and not just tightening and sent on my way? Could that be the root of the problem?