Re: Fast pedalling, why? Re: How many gears are enough?



On 9 July, 23:34, jobst.bra...@xxxxxxxxxxxxxxxxxx wrote:
Ben C? sniped:



[...]
This is not true.  Measurements have been taken on force applied
to pedals, and at anything above very low cadences, there is
significant force applied to the pedals at the bottom of the
pedal stroke and significant energy used in changing the
direction of the mass of the legs at the bottom of the pedal
stroke.
Force application studies have shown that useful force is applied
only through a short section of the pedal stroke.
Did they also show that useless or counter-useful force is applied
during other sections of the stroke?
By useless force, I mean force applied without doing any work-- such
as pushing straight down at the very bottom of the stroke.
By counter-useful force, I'm thinking of pushing down on the
up-pedal, which some inexperienced riders may do just to keep their
feet securely on the pedals.
But any energy you put in, at any point on the pedal stroke, goes
into turning the crank and pushing the bike through the air (minus
losses in the usual places-- friction, damping, etc).
It's all good, it doesn't matter whether you're putting energy in
around the bottom of the stroke, on the downstroke or even on the
upstroke (apart from more subtle physiological considerations).
Fortunately this claim is readily testable.  Position a pedal at
the bottom of the stroke and then put your full weight on it- how
much of that force is translated into forward motion?
None, but you haven't done any work either, so the efficiency is
100%.
In order to put energy in right at the bottom of the stroke, you
have to push the pedal horizontally backwards.

Ooh!  We are being reintroduced to "round pedaling" subject which
suggests that power can be generated out of nothing by additional
muscular effort.  As mentioned in the past, this hypothesis can be
tested by intermittent pedaling while at maximum speed on a level
road.  Counting 1-2-3-1-2-3-1... synchronous with the downstroke of
each foot, and then pushing down only on the count of "1" the same
speed can be maintained with the same effort.  Although this is
tedious and brings no benefit it works.  

The point is the muscular effort goes into the cranks while adding
gratuitous muscular force (round pedaling) does not enable a rider to
go faster other than in a burst (sprint).  Continuous bicycling is
power rather than force limited.  The rider with the best
cardiovascular system is the fastest rather than the guy with the
strongest muscles who are often great sprinters.

You're making assumptions that everyones physiology is the same and
remains so. Clearly wrong. There are people whose skeletal muscle is
their limitation with steady state cycling. If you get cardiac pain,
your cardio pulmonary system is your limitation. If you get skeletal
muscle pain then your vascular and skeletal muscles are your
limitation. Leg pain means you need more blood ciculating your leg.
Higher cadence does this. Cardiac pain means slow down, your skeletal
system is stressing your cardiac system to its limit, the cardiac pain
is due to a lowered oxygen level. A more efficient pedalling is
required to maintain this speed which may be a lower or higher gear.
If both cardiac and leg pain come on togather then you are in your
ideal gear, slow down a little to preserve life. Most people gear low
so the limitation from skeletal pain means they do not experience
cardiac pain without disease. The pain is generally indicative of low
oxygen levels. Reduction from leg demands by easing should rocket
oxygen levels around the heart imeadiately elliminating cardiac pain.
Continuing pain would need a non propulsive pedalling to maximise
oxygen to the heart quickly.
.



Relevant Pages

  • Re: Fast pedalling, why? Re: How many gears are enough?
    ... to pedals, and at anything above very low cadences, there is ... significant force applied to the pedals at the bottom of the ... pedal stroke and significant energy used in changing the ...
    (rec.bicycles.tech)
  • Re: Fast pedalling, why? Re: How many gears are enough?
    ... to pedals, and at anything above very low cadences, there is ... significant force applied to the pedals at the bottom of the ... pedal stroke and significant energy used in changing the ... The point is the muscular effort goes into the cranks while adding ...
    (rec.bicycles.tech)
  • Re: Fast pedalling, why? Re: How many gears are enough?
    ... significant force applied to the pedals at the bottom of the pedal ... stroke and significant energy used in changing the direction of the ... mass of the legs at the bottom of the pedal stroke. ...
    (rec.bicycles.tech)
  • Re: Fast pedalling, why? Re: How many gears are enough?
    ... to pedals, and at anything above very low cadences, there is ... significant force applied to the pedals at the bottom of the ... pedal stroke and significant energy used in changing the ... the saddle "pushing straight down" has no effect on propulsion power. ...
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