More distance per Calorie: Walk vrs Granny Gear Uphill?

[Tony Raven]

[email protected] wrote in
news:[email protected]:
>
> Well, as you wrote before:
>
> Tony Raven wrote:
>> Efficiency is normally taken as the energy needed to travel a
>> distance, not speed otherwise a Hummer would be classed as more
>> efficient than a bicycle.

You are misinterpreting things rather a lot. I said speed is not the same
as efficiency which is very different from saying that walking is only more
efficient, according to this paper, over a narrow range of (low) speeds.

>
> Indeed.
>
> The rest of the article describes the most efficient method of
> travelling up different inclines. Walking is described as being the
> most efficient above ~15%.
>

They also point out that there is an unexpectedly high energy cost of the
gradient in their cycle experiments that they cannot explain. Having
dismissed possible ones such as rolling resistance and air resistance they
come down to inefficient pedaling on a slope or the efforts to control the
bike on a short narrow treadmill.




--
Tony

" I would never die for my beliefs because I might be wrong."
Bertrand Russell

 

[[email protected]]

On 10 Sep, 16:59, Tony Raven <[email protected]> wrote:
> [email protected] wrote innews:[email protected]:
>
>
>
> > Well, as you wrote before:
>
> > Tony Raven wrote:
> >> Efficiency is normally taken as the energy needed to travel a
> >> distance, not speed otherwise a Hummer would be classed as more
> >> efficient than a bicycle.
>
> You are misinterpreting things rather a lot. I said speed is not the same
> as efficiency which is very different from saying that walking is only more
> efficient, according to this paper, over a narrow range of (low) speeds.

No I'm not. You've repeatedly posted that cycling is inherently more
efficient, with the caveat that you're not trying to cycle up stairs
etc. Others, including myself, posted that they have personal
experience of situations where pushing the bike or walking was more
efficient/effective. The paper showed evidence of where this can be
the case.

The situation I referred to where I was faster on foot than a friend
on a bike was on a hill that was sufficiently steep that I was
basically walking rather than running - and the cyclist was going
slower. Agreed, if she had been more powerful she might have been able
to get some momentum going, but she couldn't. Looks like she was stuck
in that area of the graph where walking was more efficient.

 

[_]

On Mon, 10 Sep 2007 16:24:29 -0000, [email protected] wrote:

> On 10 Sep, 16:59, Tony Raven <[email protected]> wrote:
>> [email protected] wrote innews:[email protected]:
>>
>>
>>
>>> Well, as you wrote before:
>>
>>> Tony Raven wrote:
>>>> Efficiency is normally taken as the energy needed to travel a
>>>> distance, not speed otherwise a Hummer would be classed as more
>>>> efficient than a bicycle.
>>
>> You are misinterpreting things rather a lot. I said speed is not the same
>> as efficiency which is very different from saying that walking is only more
>> efficient, according to this paper, over a narrow range of (low) speeds.
>
> No I'm not. You've repeatedly posted that cycling is inherently more
> efficient, with the caveat that you're not trying to cycle up stairs
> etc. Others, including myself, posted that they have personal
> experience of situations where pushing the bike or walking was more
> efficient/effective. The paper showed evidence of where this can be
> the case.
>
> The situation I referred to where I was faster on foot than a friend
> on a bike was on a hill that was sufficiently steep that I was
> basically walking rather than running - and the cyclist was going
> slower. Agreed, if she had been more powerful she might have been able
> to get some momentum going, but she couldn't. Looks like she was stuck
> in that area of the graph where walking was more efficient.

Looks as though you are saying that Tony's exception doesn't include your
situation - similar to arguing that one bit of the split hair is bigger.

 

[[email protected]]

On 10 Sep, 17:32, _ <[email protected]>
wrote:
> On Mon, 10 Sep 2007 16:24:29 -0000, [email protected] wrote:
> > On 10 Sep, 16:59, Tony Raven <[email protected]> wrote:
> >> [email protected] wrote innews:[email protected]:
>
> >>> Well, as you wrote before:
>
> >>> Tony Raven wrote:
> >>>> Efficiency is normally taken as the energy needed to travel a
> >>>> distance, not speed otherwise a Hummer would be classed as more
> >>>> efficient than a bicycle.
>
> >> You are misinterpreting things rather a lot. I said speed is not the same
> >> as efficiency which is very different from saying that walking is only more
> >> efficient, according to this paper, over a narrow range of (low) speeds.
>
> > No I'm not. You've repeatedly posted that cycling is inherently more
> > efficient, with the caveat that you're not trying to cycle up stairs
> > etc. Others, including myself, posted that they have personal
> > experience of situations where pushing the bike or walking was more
> > efficient/effective. The paper showed evidence of where this can be
> > the case.
>
> > The situation I referred to where I was faster on foot than a friend
> > on a bike was on a hill that was sufficiently steep that I was
> > basically walking rather than running - and the cyclist was going
> > slower. Agreed, if she had been more powerful she might have been able
> > to get some momentum going, but she couldn't. Looks like she was stuck
> > in that area of the graph where walking was more efficient.
>
> Looks as though you are saying that Tony's exception doesn't include your
> situation - similar to arguing that one bit of the split hair is bigger.

<sigh>

Tony's caveat was regarding unsuitable terrain like mud, gravel or
stairs - let's see: "boulder fields, scree slopes, deep snow,
overhanging rock faces" - none of which apply here. Anyway the
situation on the hill that I described is pretty much exactly the same
as the one described at the beginning of the thread (and repeated by
others throughout).

The paper indicates that, in terms of J/kg/m, above a certain gradient
the most efficient method of getting up the hill is to walk. It just
happens that the optimal speed for that to happen is - surprise! -
within the normal range of speed for walking. Well I never.

I guess the reason is because of the "dead spots" encountered when the
crank is at some angles, referred to elsewhere in the thread. I
further suppose it's because when you're having to cycle slowly
because of the gradient, you can't use your momentum to carry through
these angles on the crank that are biomechanically inefficient. A
racer would probably be able to produce a sufficient power output to
build up momentum, and thus avoid the problem.

 

[Tony Raven]

[email protected] wrote in
news:[email protected]:
>
> No I'm not. You've repeatedly posted that cycling is inherently more
> efficient, with the caveat that you're not trying to cycle up stairs
> etc. Others, including myself, posted that they have personal
> experience of situations where pushing the bike or walking was more
> efficient/effective. The paper showed evidence of where this can be
> the case.
>
> The situation I referred to where I was faster on foot than a friend
> on a bike was on a hill that was sufficiently steep that I was
> basically walking rather than running - and the cyclist was going
> slower. Agreed, if she had been more powerful she might have been able
> to get some momentum going, but she couldn't. Looks like she was stuck
> in that area of the graph where walking was more efficient.
>

You are doing it again - confusing the relative speeds at which activity
takes place as evidence of efficiency. If another friend had run up the
slope and beaten both of you, by your measure they would have been more
efficient whereas the paper you are citing rules out running completely as
an efficient way of hill climbing. I repeat the relative speeds at which
you and your friend went up that slope are irrelevant as an indicator of
efficiency.

And I doubt she was stuck in the area on the graph where walking was more
efficient as a) very few cyclists can balance on a hill at speeds of 2mph
or less and b) if you were walking faster than that then you were
definitely in the region of the graph where cycling is more efficient.

--
Tony

" I would never die for my beliefs because I might be wrong."
Bertrand Russell

 

[Tony Raven]

[email protected] wrote in
news:[email protected]:

>
> I guess the reason is because of the "dead spots" encountered when the
> crank is at some angles, referred to elsewhere in the thread. I
> further suppose it's because when you're having to cycle slowly
> because of the gradient, you can't use your momentum to carry through
> these angles on the crank that are biomechanically inefficient. A
> racer would probably be able to produce a sufficient power output to
> build up momentum, and thus avoid the problem.
>

No need to guess, the authors discuss it. After ruling out air and
rolling resistance they say:

"Only other two potential reasons can be claimed to explain the
relatively high vertical cost of gradient cycling: (1) a lower
transmission efficiency than W (walking) and R (running), as caused, for
instance, by an impaired push on the pedals on steep gradients, and/or
(2) a notable increase in co-contractions of postural muscles, necessary
to stabilize and control the bicycle while riding on a narrow and short
treadmill at slow speeds."

--
Tony

" I would never die for my beliefs because I might be wrong."
Bertrand Russell

 

[[email protected]]

On 10 Sep, 18:13, Tony Raven <[email protected]> wrote:
> I repeat the relative speeds at which
> you and your friend went up that slope are irrelevant as an indicator of
> efficiency.

That's not necessarily true. We were both likely putting out the same
amount of power, as we can run/cycle at similar speeds - I don't know,
150W. We were racing up the hill. My 150W got me higher up the hill in
a given time than hers did, so I consumed less energy per unit height
than she did.

I appreciate, though, that if running rather than cycling enabled me
to produce more power, that would be a difference in effectiveness
rather than efficiency.

Anyway I'm going out to run up Primrose Hill

 

[_]

On Mon, 10 Sep 2007 17:28:15 -0000, [email protected] wrote:


> That's not necessarily true. We were both likely putting out the same
> amount of power, as we can run/cycle at similar speeds - I don't know,
> 150W. We were racing up the hill. My 150W got me higher up the hill in
> a given time than hers did, so I consumed less energy per unit height
> than she did.
>

Well, that's comparing apples with the kind of apple spelt "O-R-A-N-G-E".

 

[[email protected]]

On 10 Sep, 12:55, [email protected] wrote:
> The book, "Bicycling Science" addresses this exact problem. They try
> to figure out at what gradient walking becomes more efficient than
> cycling. I think the figure they arrived at was around twenty percent
> and they confirmed this with actual evidence--for steep and/or rough
> routes, cyclists and runners will frequently take about the same
> amount of time to complete the course. If you think about it, as the
> grade gets steeper, more and more energy is put into simply overcoming
> the force of gravity. Meanwhile, maximum speed drops so that the
> raised gearing and lower frictional forces that normally give the
> bicycle such an advantage are no longer a factor.
>
> On Sep 6, 7:09 pm, Artemisia <[email protected]> wrote:
>
>
>
> > Peter Clinch wrote:
>
> > > I recall one incident when a pal and I were taking our MTBs up a fairly
> > > steep grassy field. I got bored at walking pace, and decided I'd walk.
> > > While walking, I soon overtook my pal, still spinning happily in 1st...
>
> > So isn't it actually more efficient energy use to walk uphill than to
> > pedal, even if you do have unimaginably low gears and no topple-over on
> > a trike?
>
> > I'm thinking perhaps the only advantage of trying to pedal up my hills
> > is the inconvenience of trying to stand up out of a recumbent...


Examine the limiting case:-

With the lowest possible gearing, namely Infinity to One
(or zero inches if you like), your legs will
spin round and round expending energy and no progress will
be made. The efficienty will be zero - the losses 100%.

Then imagine changing the gearing slightly so that some
progress is made the losses are then slightly less than
100%.

Raising the gearing further will eventually
reach the same efficiency as walking.

As the gearing is raised even further the efficiency will be
greater than that of walking and we are in the realm
of the normal bicycle.

I think therefore that

"> > So isn't it actually more efficient energy use to walk uphill
than to
> > pedal, even if you do have unimaginably low gears and no topple-over on
> > a trike?"

is indeed true.


Douglas.

 

[Paul O]

[email protected] wrote:
> On 10 Sep, 12:55, [email protected] wrote:
>> The book, "Bicycling Science" addresses this exact problem. They try
>> to figure out at what gradient walking becomes more efficient than
>> cycling. I think the figure they arrived at was around twenty percent
>> and they confirmed this with actual evidence--for steep and/or rough
>> routes, cyclists and runners will frequently take about the same
>> amount of time to complete the course. If you think about it, as the
>> grade gets steeper, more and more energy is put into simply overcoming
>> the force of gravity. Meanwhile, maximum speed drops so that the
>> raised gearing and lower frictional forces that normally give the
>> bicycle such an advantage are no longer a factor.
>>
>> On Sep 6, 7:09 pm, Artemisia <[email protected]> wrote:
>>
>>
>>
>>> Peter Clinch wrote:
>>> > I recall one incident when a pal and I were taking our MTBs up a fairly
>>> > steep grassy field. I got bored at walking pace, and decided I'd walk.
>>> > While walking, I soon overtook my pal, still spinning happily in 1st...
>>> So isn't it actually more efficient energy use to walk uphill than to
>>> pedal, even if you do have unimaginably low gears and no topple-over on
>>> a trike?
>>> I'm thinking perhaps the only advantage of trying to pedal up my hills
>>> is the inconvenience of trying to stand up out of a recumbent...
>
>
> Examine the limiting case:-
>
> With the lowest possible gearing, namely Infinity to One
> (or zero inches if you like), your legs will
> spin round and round expending energy and no progress will
> be made. The efficienty will be zero - the losses 100%.
>
> Then imagine changing the gearing slightly so that some
> progress is made the losses are then slightly less than
> 100%.
>
> Raising the gearing further will eventually
> reach the same efficiency as walking.
>
> As the gearing is raised even further the efficiency will be
> greater than that of walking and we are in the realm
> of the normal bicycle.
>
> I think therefore that
>
> "> > So isn't it actually more efficient energy use to walk uphill
> than to
>>> pedal, even if you do have unimaginably low gears and no topple-over on
>>> a trike?"
>
> is indeed true.
>
>
> Douglas.
>
Douglas,
Brilliant! Best post of the month!

--

Paul D Oosterhout
I work for SAIC (but I don't speak for SAIC)

 

[[email protected]]

On 10 Sep, 19:12, _ <[email protected]>
wrote:
> On Mon, 10 Sep 2007 17:28:15 -0000, [email protected] wrote:
> > That's not necessarily true. We were both likely putting out the same
> > amount of power, as we can run/cycle at similar speeds - I don't know,
> > 150W. We were racing up the hill. My 150W got me higher up the hill in
> > a given time than hers did, so I consumed less energy per unit height
> > than she did.
>
> Well, that's comparing apples with the kind of apple spelt "O-R-A-N-G-E".

Only if you're *S*T*U*P*I*D*

 

[_]

On Mon, 10 Sep 2007 20:54:08 -0000, [email protected] wrote:

> On 10 Sep, 19:12, _ <[email protected]>
> wrote:
>> On Mon, 10 Sep 2007 17:28:15 -0000, [email protected] wrote:
>>> That's not necessarily true. We were both likely putting out the same
>>> amount of power, as we can run/cycle at similar speeds - I don't know,
>>> 150W. We were racing up the hill. My 150W got me higher up the hill in
>>> a given time than hers did, so I consumed less energy per unit height
>>> than she did.
>>
>> Well, that's comparing apples with the kind of apple spelt "O-R-A-N-G-E".
>
> Only if you're *S*T*U*P*I*D*

I was referring to the apparent drawing of a conclusion from two situations
that differ in more than one relevant characteristic.

 

[[email protected]]

On 10 Sep, 20:33, Paul O <[email protected]> wrote:
> [email protected] wrote:
> > On 10 Sep, 12:55, [email protected] wrote:
> >> The book, "Bicycling Science" addresses this exact problem. They try
> >> to figure out at what gradient walking becomes more efficient than
> >> cycling. I think the figure they arrived at was around twenty percent
> >> and they confirmed this with actual evidence--for steep and/or rough
> >> routes, cyclists and runners will frequently take about the same
> >> amount of time to complete the course. If you think about it, as the
> >> grade gets steeper, more and more energy is put into simply overcoming
> >> the force of gravity. Meanwhile, maximum speed drops so that the
> >> raised gearing and lower frictional forces that normally give the
> >> bicycle such an advantage are no longer a factor.
>
> >> On Sep 6, 7:09 pm, Artemisia <[email protected]> wrote:
>
> >>> Peter Clinch wrote:
> >>> > I recall one incident when a pal and I were taking our MTBs up a fairly
> >>> > steep grassy field. I got bored at walking pace, and decided I'd walk.
> >>> > While walking, I soon overtook my pal, still spinning happily in 1st...
> >>> So isn't it actually more efficient energy use to walk uphill than to
> >>> pedal, even if you do have unimaginably low gears and no topple-over on
> >>> a trike?
> >>> I'm thinking perhaps the only advantage of trying to pedal up my hills
> >>> is the inconvenience of trying to stand up out of a recumbent...
>
> > Examine the limiting case:-
>
> > With the lowest possible gearing, namely Infinity to One
> > (or zero inches if you like), your legs will
> > spin round and round expending energy and no progress will
> > be made. The efficienty will be zero - the losses 100%.
>
> > Then imagine changing the gearing slightly so that some
> > progress is made the losses are then slightly less than
> > 100%.
>
> > Raising the gearing further will eventually
> > reach the same efficiency as walking.
>
> > As the gearing is raised even further the efficiency will be
> > greater than that of walking and we are in the realm
> > of the normal bicycle.
>
> > I think therefore that
>
> > "> > So isn't it actually more efficient energy use to walk uphill
> > than to
> >>> pedal, even if you do have unimaginably low gears and no topple-over on
> >>> a trike?"
>
> > is indeed true.
>
> > Douglas.
>
> Douglas,
> Brilliant! Best post of the month!
>

Illumination of the month I might go for.

Brilliant! Not at all. I was taught that at school mumble
mumble mumble years ago.

"The important thing is asking the right questions."
Me.

 

[[email protected]]

On 11 Sep, 01:36, [email protected] wrote:
> On 10 Sep, 20:33, Paul O <[email protected]> wrote:
>
>
>
>
>
> > [email protected] wrote:
> > > On 10 Sep, 12:55, [email protected] wrote:
> > >> The book, "Bicycling Science" addresses this exact problem. They try
> > >> to figure out at what gradient walking becomes more efficient than
> > >> cycling. I think the figure they arrived at was around twenty percent
> > >> and they confirmed this with actual evidence--for steep and/or rough
> > >> routes, cyclists and runners will frequently take about the same
> > >> amount of time to complete the course. If you think about it, as the
> > >> grade gets steeper, more and more energy is put into simply overcoming
> > >> the force of gravity. Meanwhile, maximum speed drops so that the
> > >> raised gearing and lower frictional forces that normally give the
> > >> bicycle such an advantage are no longer a factor.
>
> > >> On Sep 6, 7:09 pm, Artemisia <[email protected]> wrote:
>
> > >>> Peter Clinch wrote:
> > >>> > I recall one incident when a pal and I were taking our MTBs up a fairly
> > >>> > steep grassy field. I got bored at walking pace, and decided I'd walk.
> > >>> > While walking, I soon overtook my pal, still spinning happily in 1st...
> > >>> So isn't it actually more efficient energy use to walk uphill than to
> > >>> pedal, even if you do have unimaginably low gears and no topple-over on
> > >>> a trike?
> > >>> I'm thinking perhaps the only advantage of trying to pedal up my hills
> > >>> is the inconvenience of trying to stand up out of a recumbent...
>
> > > Examine the limiting case:-
>
> > > With the lowest possible gearing, namely Infinity to One
> > > (or zero inches if you like), your legs will
> > > spin round and round expending energy and no progress will
> > > be made. The efficienty will be zero - the losses 100%.
>
> > > Then imagine changing the gearing slightly so that some
> > > progress is made the losses are then slightly less than
> > > 100%.
>
> > > Raising the gearing further will eventually
> > > reach the same efficiency as walking.
>
> > > As the gearing is raised even further the efficiency will be
> > > greater than that of walking and we are in the realm
> > > of the normal bicycle.
>
> > > I think therefore that
>
> > > "> > So isn't it actually more efficient energy use to walk uphill
> > > than to
> > >>> pedal, even if you do have unimaginably low gears and no topple-over on
> > >>> a trike?"
>
> > > is indeed true.
>
> > > Douglas.
>
> > Douglas,
> > Brilliant! Best post of the month!
>
> Illumination of the month I might go for.
>
> Brilliant! Not at all. I was taught that at school mumble
> mumble mumble years ago.
>
> "The important thing is asking the right questions."
> Me.- Hide quoted text -

Bad form etc.

Brilliance is recognising this effect while not being able to
fix a puncture. (or anything else!!!!!!!!!!)
Sacre bleu!

e.g.
"EFR
Ile de France "

 

[Rob Morley]

In article <[email protected]>, Steve Gravrock
[email protected] says...
> On 2007-09-09, Rob Morley <[email protected]> wrote:
> > In article <[email protected]>, Steve Gravrock
> > [email protected] says...

> >> You don't push against anything. You pull up on the handlebars, which
> >> has the effect of pulling your upper body down and forward.
> >>
> > And the front wheel up - not the desired effect, I think.
>
> No. You can't lift the front wheel just by pulling on the handlebars
> because there's nothing to hold your body in place while you do it.

Conservation of momentum.

> What
> you suggest is no different from saying that you can sit in a chair with
> your legs off the floor and lift the chair by pulling up on it.

I can certainly tip it on its back legs, which is closer to the sort of
thing we're discussing.
>
> Watch somebody intentially wheelie sometime. They'll start by pushing up
> sharply on the bars.

ITYM pushing down sharply on the bars.

> The upward momentum of the torso generated by that
> push is what makes the maneuver possible. Without all the pulling in
> the world is only going to move you, not the front of the bike.
>
This demonstrates the good old "every action has an equal and opposite
reaction", exactly the same applies to your "pulling on the
handlebars" - you accelerate towards the bars, and the bars accelerate
towards you, lightening the front wheel. The only reason you need to
push down for extra upward momentum to pull a wheelie is because you
need to lift the front wheel quite high, but in the extreme hillclimb
scenario that started this the front of the bike is already pretty high.

 

[CoyoteBoy]

On 10 Sep, 15:01, Tony Raven <[email protected]> wrote:
> [email protected] wrote innews:[email protected]:
>
>
>
> > I don't think you're right, Tony. From experience of being faster on
> > foot than a cyclist up some hills in the South Downs (and she's fitter
> > than me), it seems pretty clear that there is a gradient above which
> > it's more efficient to walk/run. As we were both maxed out in terms of
> > energy expenditure (we were racing!) that would imply to me that both
> > efficiency and effectiveness were better for walking.
>
> > Also have a look at this article:
> >http://www.springerlink.com/content/bt3tm8ckrjt4fg54/
>
> I've only had time for a very brief scan of the paper but it seems to be
> saying there is a small zone in which walking can be more efficient than
> cycling. This is at higher gradients and velocities below 1m/s or 2.25mph
> (and above 0.1m/s) - a velocity below which most people cannot stay
> balanced on a bicycle anyway. Above that speed Fig 2b seems to indicate,
> subject to further study, that cycling is the most efficient.
>
> I may change my mind when I've had time to read it properly.
>
> --
> Tony
>
> " I would never die for my beliefs because I might be wrong."
> Bertrand Russell

I'm with you on this.

 

[[email protected]]

On 10 Sep, 23:58, _ <[email protected]>
wrote:
> On Mon, 10 Sep 2007 20:54:08 -0000, [email protected] wrote:
> > On 10 Sep, 19:12, _ <[email protected]>
> > wrote:
> >> On Mon, 10 Sep 2007 17:28:15 -0000, [email protected] wrote:
> >>> That's not necessarily true. We were both likely putting out the same
> >>> amount of power, as we can run/cycle at similar speeds - I don't know,
> >>> 150W. We were racing up the hill. My 150W got me higher up the hill in
> >>> a given time than hers did, so I consumed less energy per unit height
> >>> than she did.
>
> >> Well, that's comparing apples with the kind of apple spelt "O-R-A-N-G-E".
>
> > Only if you're *S*T*U*P*I*D*
>
> I was referring to the apparent drawing of a conclusion from two situations
> that differ in more than one relevant characteristic.

God, I thought Tony was patronising and dull, but in comparison with
you he's a breath of fresh air. Come back!

 

[[email protected]]

On Sep 10, 12:14 am, Tony Raven <[email protected]> wrote:
> [email protected] wrote innews:[email protected]:
>
>
>
>
>
> > On Sep 8, 2:52 pm, Tony Raven <[email protected]> wrote:
> >> [email protected] wrote in news:1189282212.500032.53880
> >> @y42g2000hsy.googlegroups.com:
>
> >> > Why would pedaling and putting the power through transmission
> >> > losses be more efficient/effective/et cetera than just climbing a
> >> > ladder? How does enforcing a much narrower range of speed and
> >> > cadence improve things?
>
> >> Go back and read my previous response to you about upper body
> >> movement for your answer.
>
> >> --
> >> Tony
>
> >> " I would never die for my beliefs because I might be wrong."
> >> Bertrand Russell
>
> > Dear Tony,
>
> > I'm sorry, but it didn't seem very convincing the first time.
>
> > The notion that bicyclists are not moving their upper bodies (or, to
> > be more accurate, using the muscles of their upper bodies) is
> > strange.
>
> You misunderstand the physics of the situation. Its nothing to do with
> upper body muscle use, its to do with upper body vertical movement (think
> potential energy). Lifting your body upwards with every step consumes
> energy, having it fall back down at the end of every step doesn't recover
> that energy (unlike the downstroke of the pedal under body weight while
> standing on the pedals). The energy loss walking will almost certainly
> be through the leg muscles having to work harder. As I said, try walking
> without having your upper body move up and down.
>
> --
> Tony
>
> " I would never die for my beliefs because I might be wrong."
> Bertrand Russell- Hide quoted text -
>
> - Show quoted text -

Dear Tony,

I think that you misunderstand the physics of walking up a steep
slope, where the rise and fall of level walking turns into more of a
stairstep than a sinusoidal motion.

Cheers,

Carl Fogel

 

[[email protected]]

On Sep 10, 1:14 am, Tony Raven <[email protected]> wrote:
> [email protected] wrote in news:1189406557.259000.67980
> @r34g2000hsd.googlegroups.com:
>
>
>
> > Unfortunately, the two drive shafts of a bicycle are arranged so that
> > they hit top and bottom dead center at the same time, and bicycles
> > with freewheels have scarcely any flywheel effect.
>
> There was a design of crank where the crank could move a few degrees
> relative to the chainwheel so that taking it over TDC was made easier.
> They made great claims about efficiency improvements IIRC but they don't
> seem to have survived the test of real life.
>
> --
> Tony
>
> " I would never die for my beliefs because I might be wrong."
> Bertrand Russell

Dear Tony,

I suppose that it would be something like the independent Power Crank
(or possibly Rotor Crank--I get them mixed up), where the crank arms
can move independently.

It's hard to see how even letting each crank move independently will
help the dead spot, since the rotary crank still passes through it
with little or no power applied.

Aa treadle design like this might get around the dead spot (I'm not
sure), but as you say, it never survived the test of real life:

http://i9.tinypic.com/4taqys4.jpg

Cheers,

Carl Fogel

 

[Rob Morley]

In article <[email protected]>,
[email protected] says...

> Aa treadle design like this might get around the dead spot (I'm not
> sure), but as you say, it never survived the test of real life:
>
> http://i9.tinypic.com/4taqys4.jpg
>
All you need is some sort of ratcheted spring that winds up on the
highest torque part of the stroke then unwinds around the dead spot.
The fact that it hasn't been implemented suggests that it's a solution
looking for a problem.