Originally Posted by
Holden McNeil
Shifters - Since you have road derailleurs, you need to run the Tiagra shifters (Product)
I've converted a few bikes like this, including my wife's Madone 4 series, after she had a pretty serious bike accident. It works perfectly and is so much fun to ride! As stated above, fit is the most important thing for comfort, and regardless of flat or drop bar configuration, you'll want to address any fit related issues first.
Everything I've ever read has stated that the Tiagra road shifter works better paired with a mtb FD, although the only official word from Shimano is to use the matching FD (FD-Rxxx). I've read plenty of posts in which someone was complaining about the road/drop FD not working with the Tiagra flat-bar shifter.