What is the difference between wheel speed and bike speed?

In the PowerCurve Software, wheel speed and bike speed will be displayed. Wheel speed is the speed of the wheel based on the revolution times and the wheel circumference. It’s the speed the wheel is rotating on the trainer. For the same watts the wheel speed will vary based on the trainer because of the different power curves of each trainer.

The bike speed is a precise calculation of how fast you would be going outside based the current watts you are generating, the grade, your weight and aerodynamic factor profile calculated from your weight. Lighter riders are get a smaller frontal area than heavier riders. You’ll notice on downhills (negative grade settings) that without any pedaling, heavier riders will go slightly faster even though the have a larger frontal area.

But on an uphill, the same watts will make a lighter rider have a higher bike speed.

The magic of the PowerCurve Sensor and Software is that your bike speed will be accurate without being dependent on the trainer model since the bike speed is computed from the watts. And the watts will be accurate no matter which trainer you use!