Originally Posted by
gac1982
You'll probably need to convert the left STI lever and the front derailleur to a double as well. You can buy the left STI lever separately (try jensonusa dot com, there are probably other sources as well). Or you can just go back to the triple and work harder on adjusting it. Triples are hard to adjust correctly. I know, I just converted one of my bikes to a double for that reason.
In the Tiagra group and 105 group the shifters are double-triple compatible. In 9-speed the Ultegra shifters are double triple compatible, in fact they are the same shifters.
The set-up and adjustments for a triple front derailleur and shifter is exactly the same as for a double. But accuracy seems to be more critical. The rough shifting often associated with a triple is due to the differences in chainring sizes, the size of the smallest chainring, and the more severe chain angles.