I dont have a bike computer or speedometer or odometer on my bike. If I average 14mph or 18mph, what does it matter? Enjoy the ride. Better health and conditioning is going to happen no matter what, as long as you're turning the cranks. I love it when I can ride fast and crank hard for a good distance and feel good at the end of a ride. But thats maybe 10% of my rides. The other 90% I'm tired, just not getting in the groove, weather sucks, whatever. I don't need data to show me how I feel or how good a ride I had. Ride the bike. Enjoy it.