One of the best bike shop around Tokyo. If you have plane to visit Shinjyuku, just take a Keio Line to Sasazuka then take a walk 5min.
Best tour I think I've ever been on. Go on route A and see the city of Tokyo by bike for 6 hours. Very friendly staff and you get a cold beer at the end!
Rent a bike or tandem for 200 yen and take the 1.8km course around the park. Even better in cherry blossom season.