So I've read a few good threads on this but I want to be sure and not spend money and realize it won't work. I have a Jamis xenith with a compact double 105 group. It's 50-34 and 11-25. I'm newer with knowing exactly what will fit what but I'm learning from here and I'm somewhat mechanically inclined. I'm trying to make a hill climber with this bike because that's all that's around me. The LBS told me that I'm limited to a 28 rear cog. From what I've read here I could do a sram 12-30 cassette with a ultegra long cage RD and longer chain. I'd like to go to a 32 or even 34 but again the LBS told me I couldn't use a mountain derailleur with this set up. If the 12-30 would be just a new/used cassette and chain I'm game. Even if possibly a new/used derailleur. If trying to get an 11-34 is too much money and b.s. then that's ok, but if it isn't that much more cost or hassle then I'm all for it.