Sorry for the lengthy post.
I have an issue that has really stumped me. Let’s assume that everything is installed based on Park Tools Big Blue Book, Shimano instructions and Sheldon's advice.
I’m in the process of upgrading my Trek 400 from 105 7-speed downtube to 8-speed STI. I have installed a pair of Shimano ST-2200 “sora” shifters. I’m using a 105 1056 front derailleur, rear derailleur and crank. The BB is 107mm matches the crank, based on Sheldon’s recommendation.
The right shifter indexes perfectly to an 8-speed cassette, no problems. The left shifter/front derailleur, on the other hand, is giving be some serious problems.
When I up-shift, the shifter will shift the chain to the large chainring then settle back inboard about 2mm or so. This will force the chain to rub on the inner face of the front derailleur. If I continue to toggle the shift lever to the right, the derailleur will pull slightly outboard off the chain and hit the high set screw. But once I release the lever the derailleur will settle back inboard again and start rubbing.
I have raised, lowered and twisted the derailleur in every conceivable way.
It seems that the only way I can get the derailleur off the chain is to increase the tension on the barrel adjuster on the downtube. When I do this, the adjustment seems excessive, to the point that it pulls the front derailleur out so much that it starts messing with my low setting. I’ve played around with the “bow technique” for increasing initial cable tension but that seems like a jerry-rig and I don’t like it.
I thought it might be a derailleur issue so I tried an older 1050, and a newer 5600 series. The problem exists with all of them.
In short the indexing of the front shifter does not produce enough “throw” to get the cage far enough out to clear the large chainring to even begin adjusting the high set screw.
Is this play in the left front ST-2200 shifter common and if so, what are my options to increase the outboard range of the derailleur, short of maxing out my barrel adjustor?
Sheldon seems to argue that that derailleur should not make a difference. However, should I install the matching FD-2200 unit and see if that syncs up with the shifter. Or should I say screw the STI and buy some bar-ends? I need to stimulate the economy right?
I look forward to any comments.