| |
|
Rotating
pedals and a crank mechanism are the coupling technique of choice for many
human powered vehicles. There is a maximum force that the cyclist can apply
to the pedals at any rotation speed. This will be limited by the cyclists'
weight at zero pedal velocity, unless the bike is of recumbent design and the
seat can be used to push against. As the pedal speed increases, more work
is done in moving the legs and this decreases the force that can be applied
to the pedals to provide useful work. The zero output limit is reached when
the legs can only just keep up with the pedals, but the cyclist is unable to
apply any force to them.
The pedal force provided by the rider as a
function of pedal position has the form shown. Between locations 1 and 16
there is a positive (downward) force on the pedal. One foot is therefore opposing
the work being done by the other. Only under slow rotation conditions, such
as during a hill climb, will the rider tend to pull up on a pedal as well
as push down on the other during the 'power' part of the stroke. |
|
|
|
|
|
|
|
|
|
|
|
|
