You can to rent a bike, (RENT A BİKE ISTANBUL)
Have good a time
How do I fınd that?? Im not on Facebook... :-(
You can rent a bike next to sultanahmet tram station.1 lira for a day/(or hour i forgot)but really shitty bikes.There's another place on Barbaros Blv.(Beşiktaş) next to Beşiktaş kafe pi(bar),daily 30 lira.I recommend u to insead of rent a bike just get your own.Prices are between 100-150 lira for a used bike.Just let you know Eminönü is the center of the bikes and bike parts.If you wanna get a bike you can check www.bisikletforum.com or craigslist,if u need more information you can get in touch with me.