I want to change my STI shifters from 9spd Ultegra to 10spd (because the ergonomics are better), but I'm not sure I want to go ahead with a complete conversion to 10spd including cassette, chain, then possibly front rings if the system is worn, etc.
Shimano systems can use an alternate "B" position for the derailleur cable which changes the cable-gain and allows "N" shifters to be used with "N-1" drivetrains. Therefore 10spd shifters can be used with 9spd drivetrain, 9spd shifters w/ 8spd drivetrain, etc.
I was thinking of trying this. Does this actually work? Is the shift quality good? Or am I going to wind up completely pissed off?