First, calves are very difficult to build i.e. increase the size. You may be genetically predisposed to have small calves. Many world class sprinters have massive thighs and disproportionately smaller calves. If you want to build them, you have to do some type of resistive progressive weight training. The key is to blast them with a lot of weight – frequently. That is tough to do unless you belong to a gym.

I suggest joining a gym and have a trainer recommend a weight training program to compliment your cycling.