I just did a quick 2.5 miles. On the way out, I kept between 15.5 and 16. On the way back with head winds I kept between 12.5 and 13.5. My puter reads avg speed 11.9! I know that I have the wheel size right. I did have to stop at a light once out and once back and it was a really long light. Does that account for my low avg? There just isn't anywhere out my front door that I can ride more than 1/4 mile with out a stop light or sign. It makes it a little tough to do intervals. Get up to speed, ride hard for most of a block, slow down, stop at sign, repeat.