I recently got a new triple crank for my tourer -- Shimano FC-M371. Unfortunately, after installing it, I was unable to adjust the front derailer to shift to the granny ring reliably. With the Low limit screw completely out, and no tension, it will *just barely* move to the granny, with the ring gear combinations and some luck. OK, a small heel kick to the chain also helps it

So I have bad chainline. My current BB spindle is 116 mm. Shimano's spec for the M371 is 123 mm. I went ahead and bought a 123 mm unit from my LBS.

I'm just about to install it (pulled out the old unit), and I'm having second thoughts. Shimano's spec probably assumes a front derailer of the same groupset (Altus). I have a Sora 9sp on, from a few years ago at that. The spindle is 7 mm longer in total, that means the crankset will move 3.5 mm outboard, correct? That doesn't seem like a lot. By you guys experience, will this be enough to make granny shifts good? Considering it *barely* shifts right now, sometimes.

Thanks a whole lot!