Is a V-brake lever (specifically the Avid Speed Dial 5) compatible with a side-pull road brake (specifically the Colnago X brake)? The bike is being converted from track bar (bar-end brake levers) to flat bar.
You shouldn't, but it might work. V-brake levers work for mountain disc brakes and v-brakes. Everything else needs a short pull lever.
As in the answer to this question, some people claim Avid brakes have enough adjustment to make it work. The better solution is to buy a standard pull brake lever (look for one marked for cantilever brakes for example), or use a travel agent with the V-brake (long pull) levers.