Gearing and muscle development

ive never really noticed much change in th muscle development of my legs, theyve always just been thin. last month i changed to 52-13 SS and have seen a massive change, my legs are getting bigger by the week, its really noticable.

Have you actually taken a tape measure to your legs? If you are looking at them after a big ride in a heavy gear they will be swollen, loaded with life juice or blood or something.
Measure them the day after and see if you're not hallucinating. I'd eliminate magic mushrooms from the equation before debating muscle mass questions. ;)