The answer to your question is simple and I'm surprised nobody has given you the answer, since you already supplied the evidence.
The training you are doing is basically designed to increase your leg muscles since you're not cycling specifically as an endurance rider but more like a bodybuilder or sprinter.
Let me explain:
Short, intense training (even on a bike) will break down muscle tissue so that this same tissue will repair itself (with added muscle fibres). To gain muscle you need short, sharp effort (best with weights as you can take the effort to muscular failure).
Prolonged endurance training on a bike is a different kettle of fish. If you cycle frequently (4 hours at a time) your legs should get thinner and you will more than likely lose muscle.
It's the amount of training you're doing that is affecting your leg size. Plus, by using big gears the muscles of your legs are being loaded more.
If you really want leg size, try cycling uphill for 30 minutes at max intensity but rest the following day to alow your leg muscles to rebuild.
If you don't want leg size, cycle more like an endurance rider, spin your crank and ride far more than you do presently.
ilovestacy said:
i am a newer rider, but have been told i dont ride like one. i have been really trying to find time to ride, and here is my workout.... mon-fri for 48 minutes a day on a trainer with 16-18 of those minutes being hardest gear "climbs" or all out sprints. in the summer i rode three to five hours a week and were all about the same intensity. my question is now that i am riding the trainer my leg muscles have gotten considerably larger. my legs are no thicker than before, however i am in better shape now. is this increased girth a problem or normal? i thought cyclists legs were supposed to get smaller the more you ride. is it due to my intensity or climbing??? thanks everyone. -pc