@ dabac: my bike is similar to the one here
http://www.walmart.com/ip/Power-X-Me...cycle/11089998
I have never properly measured my speed but I would say it's usually around 15 mph? The reason I want to go faster is that I am disappointed that my 3 mile commute in the morning takes 15 mins by bicycle, where I have to stop at red lights, slow down for car drivers who don't watch when they take right turns (i.e. stop before every intersection), and generally be hypervigilant. I can take an alternate route that has less intersections but the commute still takes 15 minutes. I don't think I can make 25 MPH for any reasonable stretch of time before meeting an intersection where cars need to turn against my direction of travel.