I have a 2009 Aurora Elite, it has 105 STI 10 speed shifters, Ultegra RD and a 12-27 rear cog. I was thinking to put a 9 speed 11-34 cassette. If I made this change I am assuming that the RD would need to be replaced with a mountain bike RD. This would change my low end gear inches from 30 to 23.
Would the shifter work without any problems? I don't know if the cable pull is the same or would I need to get a JTek shiftmate to cleanup any shifting problems?
And if you have a better idea, throw it out here.
I had thought of using the new 10 speed cogs and RD but this seems to be a cheaper way to go.