i have had my 105 triple for about 4 years, with the last 2 years being somewhat more active riding, say ~ 4500-5000 miles per year, so maybe 12k miles on the bike.
about 14 months ago, i replaced the rear derailer
about 2 months ago, i replaced the hanger, the chain, the cassette, and the cables.
the wheel seems to be centered
but, i just can't seem to get good shifting..., pretty much everything that can go wrong does - autoshifting, skipping...
one thing that has just started, is that when shifting the rear derailer, (i have a 12-27 cassette) it goes fine from 27 to 24, but then frequently jumps from 24 all the way to 17, skipping 21 and 19...
it appears that the shifter is usually moving to the correct index spot for the 17, but i'm not 100% sure.
i have played with the tension, and can't get this to go away.
could the problem be in the shifter?
do they just wear out..., or could something have just gone wrong in there?