Believe it or not – but you can go sightseeing in Bangkok by bicycle. There are several Bangkok cycling tour companies that offer different themed tours for tourists, or you can just rent a cheap bike yourself and following along the Rattanakosin Biking Route, which will bring you around the historic city center of Bangkok.
You can click on the image below for an enlarged version of the Rattanakosin Biking Route map.
You can also hire a “Green Bangkok Bike” for free and cycle the Rattanakosin Bicycle Route. Rental places are scattered over the district, such as at the southwestern corner of Sanam Luang, at Tha Tien Pier and beside the tourist office under the Phra Pin Klao Bridge. Officials will take a digital photo of your passport, after which you can pick up the bike. You have till 17:00 to complete the route. Be very careful of traffic though, and do not leave the designated route (as it is the only route with roads that at least resemble bicycle paths).