I lack a computer, but imagine than I can get up to 20 on the flats, if not a little higher. I usually ride a drop bar touring bike, but when it was in the shop earlier this year, I borrowed a flat bar, and actually found it faster (it had an aluminum frame, higher pressure tires). Harsher ride quality, though, and I don't know how far I could keep it up...there's not that many places I regularly ride that I can just open up for more than a few blocks at a time, and when I do longer rides I'm more concerned about endurance than speed.