Hi WantsMore. Cycling will definitely build the muscles in your legs if you do it regularly. It's such good exercise, however, that it will also cause you to lose more fat. So, what you're left with are slimmer calves and thighs that are nicely toned - the fat is replaced by muscle.

That said, there may be times where the fat loss slows while muscle tone continues to increase, resulting in your legs looking slightly bigger - but it passes. When I started riding regularly, I had big calves, but mostly fat. They did get slightly bigger after several weeks of riding but - after several more weeks of riding - they slimmed down, became much more muscular and are becoming nicely toned. Same goes for my thighs and butt. (Please note that I've been riding for almost a year now.)

For an excellent aerobic workout with little stress to your body, cycling is difficult to beat. One last thing I'm really happy with. Before I began riding, my resting heart rate was up near 80. It's now 51...