If you want to get rid of a belly....eat less
Biking is great for the heart and lungs but it's so 2 dimensional, I feel like I'm locked up in a barrel, no flexion.
I need an exercise that get's the body moving around to loosen up all the joints, I chose roller skating, was a hockey player, I skate about an hour and a half, alone, on a tennis court, both feet stay on the ground, 2/3rd's of the time going backwards, never move without music(Etymotic ER4's), for me it's relaxing and combined with a foam roller, I'm way more flexible then when just biking.
Winters are spent on an alpine snowboard (hardboots) and year round lot's of hours on a horse(excellent pelvis activity).
Muscles are great but they last about a week, constant work on joint looseness is more important to me.