Hey Balto! I didn't see this until now. I don't know where to rent bikes. There's very good road riding east of the city towards Varina. Much less traffic and hassle than going west to Powhatan and Goochland. And a great pub on the way back into town (Poe's Pub on Main Street just east of 25th).
There's also pretty good riding in town, although there are no bike paths. The traffic is light, however, and the drivers are generally well-behaved.
PM me if you want more details.