lance did a lot of weight training. mostly core, but legs too, and especially off-season.
muscle balance and flexibility are key to avoiding injury and being comfortable and powerful on the bike. cycling is like factory work: one motion repeated ad infinitum. the body was not designed for that and it will lead to imbalance and injury unless you're physiologically lucky.
swimming is the best cross-training for me, as it seems to put me "back into balance" for some reason.