Extreme Chain Slip
Im riding a Haro Escape 8.2 with a Holtzfeller 2.2RG crankset and I just replaced an older chain with a new sram 951. I am getting extreme chainslip in the front, and shortening the chain didn't help. I know the whole replace the cassette when you replace the chain thing (i haven't yet -- old chain broke so I just grabbed a new one to hold me over) but I've never heard of slip in front, even on fairly worn cogs. I cant stand up at all and i get half turn skips if i try to push hard when sitting. I never had chain slip with the old chain (the shop threw it out when they switched them, of course.)
I'm also getting a little skipping in back on the smallest 2 cogs, but they're pretty worn
Time for a whole new rings, chain, cassette, or is something else going on?
Pretty common to have chainrings slip when they are badly worn. If you let the chain get worn much more than 1% you likely need to replace the cassette and chainrings.
The LBS should have given you a heads up on the chain skip thing. The old chain was worn equally with the rings and cassette and that's why it didn't skip. Get the new rings and cassette from some where else and do the work yourself. Get the Park tool book and move on past the LBS.