Originally Posted by
Chris_W
Leave the left-hand bar-end shifter on to control the front derailleur, and only change the right-hand lever to the new STI. I run a version of this on every bike - sometimes a barend shifter for the FD, sometimes a down-tube shifter, and always STI for rear derailluer - and I love it; you can use whatever front derailleur you want and have complete control over it.
I have a right hand STI and a left-side barend on an MTB I converted to drop bars. The STI works perfectly with the rear derailleur but wouldn't work adequately with the MTB front derailleur. I couldn't change to a road FD since the odd-ball cable run of the MTB wasn't compatible with one.