gearing/chain/rear derailler issue
hey everyone, i recently built up a new touring bike and i'm running into some issue with the gearing. i have a 12-32t rear cassette with a deore long pull derailler. the front is set up for a triple, though i'm not running the granny gear right now. the large ring up front is 46t.
when i'm in the small/middle ring in the front and the 2nd to largest cog in the back, the derailler rubs against the largest cog
if i were to take a couple links out, then it would clear, however if i am in the large front chainring and the largest rear cog, the derailler just barely clears. if i were to take out any more links then it would catch the teeth in the rear. even though i would never ride in this gear ratio, i feel like this shouldn't happen.
now my understanding of the compatibility of gearing is not non-existent. even though you don't really ride in either of these gear combinations, the general rule that i've followed (which i think i got from sheldon) is that in the largest/largest chainring/cog, the chain should still have some "S" shape to it, not pulled straight... and when in the smallest/smallest, the derailler should still have a little tension to it and not allow the chain to rub against anything.
here is where my derailler sits on the largest/largest set-up.
i'm not sure how to fix this problem. as i said, i don't think i can take any links out of the chain, and adding a couple would only make matters worse. i also know that deraillers and cassettes need to be compatible, but i have yet to come across a derailler with longer reach than the one currently on the bike. i've also played with the adjustment screw on the back of the derailler that pushes against the dropout on the frame, but that hasn't seemed to help much either