You can then be picked up by a long tail boat, if you are doing the route by boat and bike you will need to arrange for a pick up and drop off this can be arranged with the long tail boat drivers who stay under pinklao bridge.
The first pickup by the boat would need to be from the park/gardens which is near Rama 8 bridge (It should take about 15 to 20 mins to ride there from Pinklao Bridge) when you ride across the bridge the gardens will be on the left with a wall running around the outside and a pier. The boat needs to take you to Taling Chan Floating Market. (if you don't want to do this first part you can easily get a Long Tail boat straight from under pinklao bridge to the market).
The route then takes you on your bike through some busy streets and then to a quiet side of Bangkok. On the way you will experience local life and see some mysterious ancient temples which date back to the Ayutthaya period. There is an option to stop at a local restaurant beside the river for some traditional Thai food.
Continue the ride passing some more temples and arriving at the famous Wat Chalor temple (a giant temple shaped like an ancient boat). For the final part of the trip the long Tail boat needs to take you from Wat Chalor for 25 mins back to Pinklao bridge.
Please see the Map below for the route, Don't forget to arrange with a long tail boat for pickups and dropoff before you start from under pinklao bridge also make sure you agree on a price. Alternatively you could do the same and replace the boat with a tuk tuk or taxi but the boat is much more fun and interesting.