Specifications

157
APPENDIX C
Appendix C
Z8 Bike Owner’s Guide
As you ride the Z8 Bike, your exercise intensity is best
measured as the amount of power received by the bike from
your pedaling. This power is usually expressed in watts. The
watts measurement is calculated from your pedaling speed
(called cadence) multiplied by the amount of resistance on the
pedals (called torque). (See Feynman, Lectures on Physics,
1971.)
In most cases it is desirable to keep the exercise intensity
constant, no matter what the pedal cadence, since it allows
accurate control of the rider's workout. This kind of workload
control is called constant power. If you pedal faster, the
resistance on the pedals (torque) is reduced by the same
amount. If you pedal slower, the resistance is increased.
If, instead, the amount of resistance on the pedals stays the
same when your cadence changes, your workload intensity will
vary directly with your cadence. If you pedal twice as fast,
your exercise intensity doubles. This kind of workload control
is called constant torque.
Constant power is used by the Z8 Bike in most cases, in order
to provide the most accurate workload control. This is
especially important in heart rate control workouts and the
Calorie Goal program.
A negative side-effect of constant power is that at very low
cadences, such as below 55 rpm, the amount of extra torque
applied to the pedals to keep power constant is so great that
the rider may not be able to keep the pedals moving. To
reduce this problem, the bike changes to constant torque at
cadences below 55 rpm, preventing any further increases in
torque. The computer will also warn you that it is no longer
able to control exercise intensity.
CONSTANT
POWER AND
CONSTANT
TORQUE