I now have a 10 speed rear cassette with a 12-27 cluster. I would like to use a 9 speed cassette with a 12-34 range for touring.
I know I need to change my RD (now a Shimano Ultegra short cage). Do I also need to change my STI Brifters (now a 10 speed 105 model)?
Can I use a Shiftmate to keep from changing brifters?