Re: Are Shimano RSX combined lever/gear compatible with v brakes
Not really, no.
They'll pull about half the cable you need for V-brakes to work well, so the pads will have to be set too close to the rim, the brakes will feel spongy and grabby, and you'll run out of lever travel when the pads wear.
There are a few options. Short mini-V-brakes work much better with road levers, subject to tyre clearance. Travel Agents will increase the cable pull. Ditch the V-brakes for cantilevers. Ditch the STI levers and use bar-end shifters with V-specific levers from Cane Creek, Tektro, or Dia Compe. Get some (expensive) Paul Crosstops or Strange Cycles brakes.