alcjphil

I think that this is probably your situation. Shimano in its wisdom decided to redesign its mechanical brakes a couple of generations ago. Their newer road brake levers pull more cable for a given amount of brake lever travel thus reducing mechanical advantage. I simply don't know if your brake callipers are designed to account for that reduced mechanical advantage. Shimano's rim brake callipers are made to work with this new system which I believe is called "super slr" if memory serves. From what I hear, brake levers and rim brake callipers that share that newer system work superbly well together but this does pose problems when aftermarket suppliers come into the picture. Specking a bike is an art, and companies that place orders from various manufacturers don't always get it right.
Perhaps in your case the Spyke mountain bike version might work better. You would only need one if your rear braking is adequate