I started serious body building about 6 months ago (got tired of looking at large thighs and nothing else), and have learned a few things about strength and muscle bulk.
Cylcling will develop strength and stamina, but not bulk. The muscles used in cycling are mostly slow-twitch fibres, and they aren't the ones that give you bulk. They will give you solid muscles made for endurance, though.
If you want to build bulk (like I've been doing on my upper body), you need to pump iron, not cycle. Creatine also helps add bulk.