the easiest way if you don't have a cadenc counter is to count how many pedal strokes you take in a min - that would give you RPM or cadence. If you don't feel like counting Or you're pedaling so fast you can't keep count ( ) I believe the easiest way to "spin" - ride with as little resistence as you can. Just keep dropping the gears until you're maintaining 13 mph/kph? (I forget what you use there) without pushing the gear. I'd say without resistence but that can open a can of worms. It's how I visual it. If you feel like you're starting to push, drop down another gear. You don't want to be bouncing around on your seat but you shouldn't feel like your pushing the pedals as you ride. I know it sounds impossible to pedal faster and still maintain your speed, but you can...and your knees and legs will thank you!