"Peter Cole" <[email hidden]> wrote in message news:<Kk0Mb.19072$xy6.52817@attbi_s02>...
Quoted message said:"Andrew Bradley" <[email hidden]> wrote
Quoted message said:
But you are not "making steps" on a bike in the normal sense. Although similar muscle groups and
joint angles may be used as compared with, say, walking uphill, loads-wise the activities are
very different.
How so?
Dear Peter,
To start from the bottom, walking involves rolling your entire weight from toe to heel, not pushing
down with far less weight on a cleat under the ball of your foot.
True, riders standing up and heaving on the handlebars will throw their whole weight onto a pedal as
they struggle up a steep climb, but this is rarely sustained for long--they're fighting the leverage
of all that gearing, which is absent from walking uphill.
That is, even with a mountain bike's granny gear down to a roughly 1 to 1 ration, your foot goes
around a circle of about 1100mm (the circumference for a 175mm crank), while the rear tire rolls
through a circle of about 2100mm--almost twice as far.
For all but the most extreme riding, the bicyclist's foot, ankle, knee, and hip bear far less than
their normal weight. Most of the weight rests on the underside of the pelvic bone, with our hands
taking additional weight on the handlebars.
The angle at which our legs flail on a bicycle is quite different from the angle of normal walking.
To be blunt, we pedal while hunched over like gorillas, our knees coming up much higher than they do
when we're walking.
Even the supposedly upright mountain bike involves bending over and leaning on the handlebars.
Ride no hands and sit bolt upright as if you were striding along on your hind legs, and you'll
probably be unable to touch the bars with your fingertips, much less grasp them. Your head will
rise a foot or more.
Serious riders tend to use high cadences with lighter pedal pressure, rather than slower cadences
with heavier pedal pressure. This simply isn't possible when walking--you have to raise your weight
with each step as you climb. The closest that walking comes to a bicycle gearing down is when we
shorten our stride, but there just isn't much gearing range available with a normal climbing stride.
Notice how awkward it is to climb stairs that are even slightly steeper, shallower, narrower, or
broader than normal.
Finally, of course, pedalling is practically free of impact. Stress fractures of the foot are almost
unheard of in cycling for the same reason that bicyclists rarely complain about blisters on their
feet until they break down and have to walk their bikes home--normal pedalling involves far less
pressure and far less impact than ordinary walking.
There are all sorts of other differences, but foot action, load, posture, cadence, and impact are
good places to start when comparing walking to pedalling. Fascinating details are easily discovered.
For example, just as some people lack ear-lobes, other people lack a vestigial leg muscle, the
plantaris.
Carl Fogel
