There have been studies that have shown that cycling alone without some sort of cross-training can cause low bone mass and deterioration of bone tissue over time. This is because cycling is considered a low impact sport. One study compared the bone densities of cyclists, runners and weight lifters, and found the cyclists had the lowest. I personally know of a couple riders from our area who in the past have been evaluated with brittle bone disease. Of course this can come as a surprise to a rider that logs at least 5,000 mi. per year.
Consider doing some sort of weight training, at least in the off season, and increasing your calcium intake to at least 800 mg daily, and women about 1,200 mg. Vitamin D is also essential to bone health, and while sunshine is an excellent source, wise use of sunscreen can block vitamin D production. Many multivitamins contain anywhere from the daily value of 400 International Units (IU) up to more likely effective and appropriate dose of 800-1,000 IU daily.