Cycling Maintained Speed

I'm still trying to figure out how best to train with cycling and all that, but with my new cyclocomputer that makes things a little easier. I'm technologically impaired so I'm still getting used to the darn thing, but I somehow set it in kilometers per hour. Good thing I remembered all the conversion formulas from highschool physics. The highest speed I was able to maintain for a short duration (about 1/4 mile) was 36 km/hr which converts to about 22.4 MPH, and the highest speed I was able to maintain for a longer duration (roughly 2 miles) was about 17 MPH. Hopefully these numbers will go up when the frequency of my rides increase.