This doesn't appear to apply in your case but I had this exact problem even after putting on a brand new groupset including a new chain. It drove me crazy trying all the usual solutions: hanger alignment (in my experience its almost always the hanger!), B-screw, fine barrel adjustments, cable lube, chain length... everything I could think of. Then I finally figured it out: I have adjustable dropouts on my new Salsa Fargo frame and the wheel wasn't perfectly aligned, though it appeared centered by eye. It only took a small correction in one dropout for the shifting problem to go away completely.
Its amazing to me that a fraction of a mm of axle alignment would throw the shifting off, but in my case it really did. So for anyone with sliding dropouts or a Salsa "Alternator" type thing like mine, be sure to check that your rear axle is truly parallel to the bottom bracket.
Its amazing to me that a fraction of a mm of axle alignment would throw the shifting off, but in my case it really did. So for anyone with sliding dropouts or a Salsa "Alternator" type thing like mine, be sure to check that your rear axle is truly parallel to the bottom bracket.
