It says recreational cyclists don't need to worry about it. What's not very helpful about studies like these is that they don't really say how much is too much. I'm not an uber-competitive cyclist but I'm not a recreational cyclist either. Makes you wonder about people who take spin classes.

What is good news is that it seems like for even the competitive or really high mileage rider that the problem can be avoided by incorporating some things known to increase bone mass. Triathletes both ride and swim, - apparently neither of which is particularly good for bone mass. Yet the fact that they run too seems to be enough to counteract the ill effects.