Beware of PowerCranks

On Aug 3, 5:48 am, Doug Taylor wrote:
On Fri, 03 Aug 2007 02:58:02 -0500, Ben C wrote:

Very few people actually apply 5lbs to the cleat on the up stroke. Many
riders pull the leg up a little bit, enough perhaps to lift about half
its weight. This counts as a contribution towards forward motion in that
it saves leg B lifting the entire weight of leg A, but leg A is still
being pushed up by the pedal. If you lifted the whole weight of leg A
(so there was 0 force on the cleat) or more (so there was say 5lbf
pulling shoe A up out of the cleat) you would be doing a great deal of
lifting and definitely pedalling in circles. But they've done studies
and no-one actually does that.

Anybody have any comment as to whether or not there are any
substantial differences between lower cadence pedaling while climbing,
as opposed to higher cadence pedaling while spinning on flatter
terrain? In my experience, it seems the steeper the climb, the
greater the load, the more muscular power required, the lower the
cadence, the more "circular" the stroke.

I think people naturally gravitate to lower caadences when they need
the most power because they naturally sense when they are the most
efficient, so generating the most power for the same (or, usually,
increased) effort. Another possible reason, is few have the gearing on
their bike that would allow them to maintain a 90-100 cadence up any
kind of reasonable climb without going way beyond their power
abilities. Want to ride like Lance you need to put out power like
Lance. Unless you are putting out 400+ sustainable watts climbing at a
cadence of 90 is not for you.

In article ,
Doug Taylor wrote:

On Fri, 03 Aug 2007 02:58:02 -0500, Ben C wrote:

Very few people actually apply 5lbs to the cleat on the up stroke.
Many riders pull the leg up a little bit, enough perhaps to lift
about half its weight. This counts as a contribution towards forward
motion in that it saves leg B lifting the entire weight of leg A,
but leg A is still being pushed up by the pedal. If you lifted the
whole weight of leg A (so there was 0 force on the cleat) or more
(so there was say 5lbf pulling shoe A up out of the cleat) you would
be doing a great deal of lifting and definitely pedalling in
circles. But they've done studies and no-one actually does that.

Anybody have any comment as to whether or not there are any
substantial differences between lower cadence pedaling while
climbing, as opposed to higher cadence pedaling while spinning on
flatter terrain? In my experience, it seems the steeper the climb,
the greater the load, the more muscular power required, the lower the
cadence, the more "circular" the stroke.

IIRC there were studies showing that mountain bikers tended to have a
more "circular" spin than road bikers, with the hypothesis being that
they developed this from spinning tiny gears up steep inclines while
seated to maintain traction. Maybe this was in VeloNews? Man, it was
years ago and maybe my memory of it is FUBAR'd.

"Doug Taylor" wrote in message
...
On Fri, 03 Aug 2007 02:58:02 -0500, Ben C wrote:

Very few people actually apply 5lbs to the cleat on the up stroke. Many
riders pull the leg up a little bit, enough perhaps to lift about half
its weight. This counts as a contribution towards forward motion in that
it saves leg B lifting the entire weight of leg A, but leg A is still
being pushed up by the pedal. If you lifted the whole weight of leg A
(so there was 0 force on the cleat) or more (so there was say 5lbf
pulling shoe A up out of the cleat) you would be doing a great deal of
lifting and definitely pedalling in circles. But they've done studies
and no-one actually does that.

Anybody have any comment as to whether or not there are any
substantial differences between lower cadence pedaling while climbing,
as opposed to higher cadence pedaling while spinning on flatter
terrain? In my experience, it seems the steeper the climb, the
greater the load, the more muscular power required, the lower the
cadence, the more "circular" the stroke.

I would offer that the greater the power/wattage for a given rpm, the more
circular the stroke, with "circularity" dropping off at lower end of the rpm
range. Angle of climb is irrelevant.

On Aug 3, 6:35 pm, wrote:
On Aug 3, 1:37 am, wrote:

On Aug 3, 2:14 am, wrote:

Everyone pedals in circles to some degree, in
that they do some work on the back stroke, the only question is how
much do they do? [...] What they forget is the effects of
gravity on those measured forces.

You're saying that on the moon your cranks would be one-sixth as
effective?

One-sixth as effective as what? bicycle cranks? training devices to
train "circular" pedaling on earth? training devices for space?

I don't know. I'm asking. You're saying that everyone but you forgets
acceleration due to gravity. So can you estimate the difference in
power an astronaut could make if he used a regularly-cranked ergometer
on the ISS?

On Aug 3, 10:21 pm, wrote:
On Aug 3, 6:35 pm, wrote:

On Aug 3, 1:37 am, wrote:

On Aug 3, 2:14 am, wrote:

Everyone pedals in circles to some degree, in
that they do some work on the back stroke, the only question is how
much do they do? [...] What they forget is the effects of
gravity on those measured forces.

You're saying that on the moon your cranks would be one-sixth as
effective?

One-sixth as effective as what? bicycle cranks? training devices to
train "circular" pedaling on earth? training devices for space?

I don't know. I'm asking. You're saying that everyone but you forgets
acceleration due to gravity. So can you estimate the difference in
power an astronaut could make if he used a regularly-cranked ergometer
on the ISS?

regarding your comment that everyone but me "forgets" acceleration due
to gravity - Have you ever seen anyone else mention that the forces on
the pedals do not actually represent the muscular forces involved? I
haven't, at least in any of these threads.

I am not sure what an astronaut can or would do on the ISS. Their
problem is going to be that unless they are somehow glued to the seat
their forces have to be completely balanced or they are going to fly
off the seat. I am sure this takes a little (or a lot of) getting used
to and since their main job is not to see how good they can get on the
exercise bike but, rather, simply maintain enough muscular and
cardiovascular fitness such that they might be able to actually stand
up when they return to earth, I suspect most of them see substantial
drops in power compared to what they could do on the earth before they
went into space.

On Aug 4, 7:51 pm, wrote:
On Aug 3, 10:21 pm, wrote:



On Aug 3, 6:35 pm, wrote:

On Aug 3, 1:37 am, wrote:

On Aug 3, 2:14 am, wrote:

Everyone pedals in circles to some degree, in
that they do some work on the back stroke, the only question is how
much do they do? [...] What they forget is the effects of
gravity on those measured forces.

You're saying that on the moon your cranks would be one-sixth as
effective?

One-sixth as effective as what? bicycle cranks? training devices to
train "circular" pedaling on earth? training devices for space?

I don't know. I'm asking. You're saying that everyone but you forgets
acceleration due to gravity. So can you estimate the difference in
power an astronaut could make if he used a regularly-cranked ergometer
on the ISS?

regarding your comment that everyone but me "forgets" acceleration due
to gravity - Have you ever seen anyone else mention that the forces on
the pedals do not actually represent the muscular forces involved? I
haven't, at least in any of these threads.

I am not sure what an astronaut can or would do on the ISS. Their
problem is going to be that unless they are somehow glued to the seat
their forces have to be completely balanced or they are going to fly
off the seat.

Then what would an astronaut be able to do on Mars?