I'm looking at putting a flat-bar setup on my girlfriends bike. The front derailleur is a Tiagra FD-4503. Rear derailleur is 105 9-speed RD-5600. I'm looking at SL-R440 or SL-R660 for shifters.
I've read these shifters are compatible with the rear mech, but do I have to replace the front mech with a FD-R453?
Thanks!