I recently bought a bike from Nashbar using a 20% off code. I'm just getting into doing my own maintenance and thought this would be a good opportunity to learn while I assemble it. The bike came with a 12-25 (10 speed) cassette and compact crank. The rear derailleur is a 105 which from what I've read should accept up to 30t. Our area is pretty hilly so I ordered a 12-30 and put it on. I also got a new chain and measured it using the "two biggest rings" method. OK. New chain and cassette are on. Feeling good. Now I think I have to check my limiter screws. That's where the good times end. When I'm in the big ring in the front, I can't shift to the two biggest gears in the back. If I'm in the biggest in the rear and small up front, shifting the big front ring causes the chain to get stuck half on the ring and everything seizes up. Can't turn the crank. I know cross chaining is frowned upon (but maybe less so with a double?), but this can't be normal. So where did I go wrong? Chain too short? Misread the 105's capacity? Thanks.