Hello all! I just got a 2015 gt grade tiagra. I have a 2012 Fuji cross 2.0 that came with 10 speed ultegra in the rear and 105 in the front. The fuji has about 400 miles on it. My question is which is better 2012 ultegra-105 mix or 2015 Tiagra? Is there much of a difference? The GT's cables are fully sheathed but the back end does not shift properley, I was told by performance that the mechanic spent 1 hour trying to get it to shift correctly but because of the full sheathing that it needs to "break in". What do you think? Thanks in advance for all replies.