Hi everyone, glad to have found this forum - my first post here
I have a 2012 BMC SL01 Road Racer, 105. I keep it clean and well maintained and it's all in perfect shape, but I've never been impressed with the rear shift, especially coming from the SRAM X9 on my 2011 MTB. (I'm not trying to start the inevitable flamewar here, it's just my empirical observation!). What I'd like to establish is whether my 105 shift is below par and can be improved, or whether "that's just how they are". Any thoughts most welcome!
Having checked (and fixed) hanger alignment and adjusted limit screws, it's still impossible to find any indexing adjustment where it's happy to go all the way up and down the cassette, click by click. The best I can get is to adjust it so that it just about clicks up a gear (i.e. to a smaller sprocket), and then accept that I sometimes need to "over shift" beyond the first click to drop down to a bigger sprocket. Of course that's not possible when doing double shifts as there's no additional movement in the lever after two clicks. It's worse around the smallest couple of cogs, sometimes the first click down from top gear will just be "absorbed" and it takes a second click to get it to next sprocket, which screws up the alignment for the rest of the cassette.
I had hoped that fixing the hanger alignment would solve it, but there's been little improvement. It feels like the dérailleur is "weak" - as if it doesn't have enough pull against the cable to keep everything really taught. It just seems vague and unsatisfactory and not what I'd expect after 2+ decades of indexing development! In comparison my SRAM X9 shift is so positive and precise, and yet that has a harder life - larger cog gaps, dirt, lower chain speeds... Should I expect better from my 105?
Thanks for any thoughts!