I have a tiagra triple in the front. It seems to have an extra shift, both as I move from the smallest to the middle chainring, and also from middle back down to the smallest.
I adjusted the high/low and then the index, but can't seem to get rid of the kink in shifting. The bike is relatively new, less than 1,000 miles.
Is it the trim control? Does the tiagra have trim control? On my Ultegra triple, there are 2 extra shifts from the lowest to highest chain rings. These act to fine tune the location of the derailer when the rear cassette are in the higher gears.