Heck, just riding the bike, any bike any style will do wonders for the leg muscles if you work hard at it. I remember training for a big climbing ride, 6 months of good riding and diet. Funny thing is after a good workout and a shower, I'd lay on the bed to relax. I'd look down to see my legs, my thighs bulging and cut and I would think to myself, no way, those aren't my legs!