I rented a bike 1 week a go from Allo Velo and here is a brief review of my experience. You can't rent a bike for less than 5 hours. I only used it for 2 hours and paid full price ($25). The manager was so kind to let me use the remaining 3 hours the next day. To be frank, I couldn't imagine that he would accept. Isn't it amazing ! That's called great service.
The location is ideal, few minutes from the Canal or the Old port! They also offer bike maintenance and reparation at a very affordable prices. While waiting for your bike to get serviced, you can enjoy their coffee on comfy couches.
For amateurs, they rent or sell a nice variety of European bikes.