More distance per Calorie: Walk vrs Granny Gear Uphill?

[Artemisia]

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...

EFR
Ile de France

 

[A.Lee]

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 would think that cycling up would be less efficient.
In both cases, you need to get the same weight up the same
height/distance.
The cycle will not be 100% efficient in transferring power to the
wheels.However, there may be a slight advantage with the very low
rolling resistance, compared to friction of the feet/tarmac interface.
Maybe not.
The legs walking up will be a lot more efficient in tranferring the
power to make forward progress, so I'd assume walking would be the most
energy efficient way.
Over to the physicists.
Alan.

--
To reply by e-mail, change the ' + ' to 'plus'.

 

[Tony Raven]

Artemisia <[email protected]> wrote in
news:[email protected]:
>
> 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...
>

Cycling is a more efficient way of moving than walking so cycling up will
use less energy

--
Tony

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

 

[Artemisia]

Tony Raven wrote:

> Cycling is a more efficient way of moving than walking so cycling up will
> use less energy

Is cycling more efficient than walking under all circumstances? Are you
speaking from experience?

EFR
Ile de France

 

[Martin Dann]

Artemisia wrote:
> Tony Raven wrote:
>
>> Cycling is a more efficient way of moving than walking so cycling up
>> will use less energy
>
> Is cycling more efficient than walking under all circumstances? Are you
> speaking from experience?

Just a quick guess here, but is cycling up a 45degree
slope similarly efficient to running up a 45 degree flight
of stairs at the same speed?
(for a weightless bike).

Martin.

 

[Roger Zoul]

Martin Dann wrote:
:: Artemisia wrote:
::: Tony Raven wrote:
:::
:::: Cycling is a more efficient way of moving than walking so cycling
:::: up will use less energy
:::
::: Is cycling more efficient than walking under all circumstances? Are
::: you speaking from experience?
::
:: Just a quick guess here, but is cycling up a 45degree
:: slope similarly efficient to running up a 45 degree flight
:: of stairs at the same speed?
:: (for a weightless bike).
::
:: Martin.

Can one cycle up a 45 degree slope? Isn't that 100% grade?

 

[Tony Raven]

Artemisia <[email protected]> wrote in
news:[email protected]:

> Tony Raven wrote:
>
>> Cycling is a more efficient way of moving than walking so cycling up
>> will use less energy
>
> Is cycling more efficient than walking under all circumstances? Are
> you speaking from experience?
>

No I'm speaking from the research evidence. Walking takes about 40% more
calories per mile than cycling for commuting and the difference can be much
more. If you had a really heavy bike it might equal things out a bit on a
hill but it would have to be really heavy.
http://ffden-2.phys.uaf.edu/211.fall2000.web.projects/J%
20Krizek/humanpower%20page%203.html

--
Tony

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

 

[Artemisia]

On 7 sep, 00:28, Martin Dann <[email protected]> wrote:

> Just a quick guess here, but is cycling up a 45degree
> slope similarly efficient to running up a 45 degree flight
> of stairs at the same speed?
> (for a weightless bike).

Why running?

EFR
Ile de France

 

[Artemisia]

On 7 sep, 02:17, "Roger Zoul" <[email protected]> wrote:

> Can one cycle up a 45 degree slope? Isn't that 100% grade?

Well if it can't even be done, then it can't be as efficient, can it?

EFR
Ile de France

 

[[email protected]]

On Sep 7, 2:38 pm, Tony Raven <[email protected]> wrote:
> Artemisia <[email protected]> wrote innews:[email protected]:
>
> > Tony Raven wrote:
>
> >> Cycling is a more efficient way of moving than walking so cycling up
> >> will use less energy
>
> > Is cycling more efficient than walking under all circumstances? Are
> > you speaking from experience?
>
> No I'm speaking from the research evidence. Walking takes about 40% more
> calories per mile than cycling for commuting and the difference can be much
> more. If you had a really heavy bike it might equal things out a bit on a
> hill but it would have to be really heavy.http://ffden-2.phys.uaf.edu/211.fall2000.web.projects/J%
> 20Krizek/humanpower%20page%203.html

But you are assuming that the "research evidence" about general
cycling (including level and downhill riding) also applies to the
specific case of cycling up a steep hill. Clearly there are such large
and fundamental differences in the physics that this hypothesis is at
best...a hypothesis. It's not an implausible null hypothesis when the
slope is reasonably shallow and the surface firm, but I don't see any
reasonable basis for it in steep and soft conditions (and anecdotal
evidence suggests it is wrong).

In soft mud (or sand, see below) there is no question that cycling can
be harder work, even on the level. Again, that is exactly as expected
from simple physical principles.

http://www.japanprobe.com/?p=2585

James

 

[[email protected]]

On 6 Sep, 18:09, 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?

According to wikipedia:

"On firm, flat, ground, a 70 kg man requires about 100 watts to walk
at 5 km/h. That same man on a bicycle, on the same ground, with the
same power output, can average 25 km/h, so energy expenditure in terms
of kcal/kg/km is roughly one-fifth as much."

http://en.wikipedia.org/wiki/Bicycle_performance

I've found other references on the same lines that suggest that
calories per hour for cycling and walking are about the same. [1] One
said walking used 25% more; this site

http://www.coolnurse.com/calories.htm

suggests that per minute, cycling uses more calories than walking. It
also says the difference is greater if you weigh more. Comparing
walking at 4 mph and cycling at 10 mph, if you weigh around 110 lbs
you will use 20% more calories cycling than walking, but at 190 lbs,
cycling will use over twice as many calories per minute. [3] It would
still be more efficient per mile than walking, because you are
travelling 2.5 times as fast, but the difference is quite small.

Anyway, coming back to the original question and for simplicity,
taking the (never known to be wrong ;-) wikipedia figure of cycling
and walking using the same number of calories per minute: the answer
is then simple, the most efficient method is the one that gets you up
the hill quickest. If you think you will be quicker walking than
cycling and want to save energy, get off and walk (if you want to lose
weight, stay on and pedal). Peter almost certainly used less calories
getting up the hill than his spinning friend.

Rob

[1] These comparisons are only valid at moderate cycling speeds - as
you go faster more of your energy goes in to overcoming wind
resistance - according to this calculator [2], to increase your speed
from 15 mph to 27 mph, you have to increase your power output from 100
W to 500 W.

[2] http://austinimage.com/bp/velocity/velocity.html

[3] Personally I find the steep increase in calorie requirement for
increasing weight suggested by this site rather difficult to believe.
The heavier person will use significantly more energy accelerating to
10 mph, but that's a one off. They will presumably be bigger and so
have slighly more air resistance to overcome and slightly greater
friction losses, but I can't see how those would add up to such a huge
increase in calorie consumption.

 

[Nick Kew]

On Thu, 06 Sep 2007 19:09:41 +0200
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...

A rest is as good as ... using different muscles?

> 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?

The inefficiency of walking is the energy you (irretrievably) lose
when the centre of gravity of the body moves up&down every step.
That's the fundamental reason cycling is more efficient.

If cycling loses a lot of energy - e.g. onna rocky or dusty trail -
it can lose its advantage. Somewhere before becoming impossible,
it becomes b***** hard work!

I recollect a coupla years ago thinking on this after I cycling up
a local tor. I passed through a local car park, where a pair of
walkers were setting out on the same route, same time as me, and
(I think) about the same pace as I'd have done if walking briskly.
Left them way behind on the easy grass slope. Higher up, on rougher
ground, they were gaining on me, and we reached the top at the same
time. I thought that said something about cycling vs walking.

--
not me guv

 

[Roger Merriman]

Tony Raven <[email protected]> wrote:

> Artemisia <[email protected]> wrote in
> news:[email protected]:
> >
> > 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...
> >
>
> Cycling is a more efficient way of moving than walking so cycling up will
> use less energy

not sure about that given a steep enought gradient. certinaly some hills
are easyer to walk up or push a bike than ride up it. one of the hills
nr my folks place is like that, this said it's not equal at 30-35% you
spend a fair effort keeping the weight right, and even riding slowly up
in a 20inch gear you are faster than you'd walk up, not by much it has
to be said. mind you plenty wouldn't want to walk up let alone bike up
it.

cars have failed to get up it. and few years back some some american
OAP's had a terrifing ride down it in a bus. luckly for them there is a
chicane in the middle as by that point, the brakes, gears, engine etc
had all burnt out....

roger
--
www.rogermerriman.com

 

[Tony Raven]

"[email protected]" <[email protected]> wrote in
news:[email protected]:

> On Sep 7, 2:38 pm, Tony Raven <[email protected]> wrote:
>> Artemisia <[email protected]> wrote
>> innews:[email protected]:
>>
>> > Tony Raven wrote:
>>
>> >> Cycling is a more efficient way of moving than walking so cycling
>> >> up will use less energy
>>
>> > Is cycling more efficient than walking under all circumstances? Are
>> > you speaking from experience?
>>
>> No I'm speaking from the research evidence. Walking takes about 40%
>> more calories per mile than cycling for commuting and the difference
>> can be much more. If you had a really heavy bike it might equal
>> things out a bit on a hill but it would have to be really
>> heavy.http://ffden-2.phys.uaf.edu/211.fall2000.web.projects/J%
>> 20Krizek/humanpower%20page%203.html
>
> But you are assuming that the "research evidence" about general
> cycling (including level and downhill riding) also applies to the
> specific case of cycling up a steep hill. Clearly there are such large
> and fundamental differences in the physics that this hypothesis is at
> best...a hypothesis. It's not an implausible null hypothesis when the
> slope is reasonably shallow and the surface firm, but I don't see any
> reasonable basis for it in steep and soft conditions (and anecdotal
> evidence suggests it is wrong).
>
> In soft mud (or sand, see below) there is no question that cycling can
> be harder work, even on the level. Again, that is exactly as expected
> from simple physical principles.
>
> http://www.japanprobe.com/?p=2585
>



Yes I am sure you can come up with all sorts of scenarios - boulder
fields, scree slopes, deep snow, overhanging rock faces.... where cycling
is less efficient than walking but that was not the tenor of the original
question not did I feel it necessary to caveat every possibility in my
original reply. But please feel free to point out my omissions.

Meanwhile perhaps you could elucidate for us what the "large and
fundamental differences in the physics" (other than the weight of the
bike) are and why the angle of a typical road surface should reverse the
efficiency relationship between cycling and walking. Reference should be
made to the equation

W = kr.Ms + ka.A.s.v2 + g.sin i.Ms

where W is power, kr is the rolling resistance coefficient, M is the
combined mass of cyclist and bicycle, s is the bicycle speed on the road,
ka is the air resistance coefficient, A is the combined frontal area of
cyclist and bicycle, v is the bicycle speed through the air (i.e. road
speed plus head wind speed), g is the gravitational acceleration
constant, and i is the road angle (DiPrampero PE, Cortili P, Mognoni P,
Saibene F (1979). Equation of motion of a cyclist. Journal of Applied
Physiology 47, 201-206)

--
Tony

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

 

[Tony Raven]

[email protected] wrote in news:1189153311.747067.116280@
22g2000hsm.googlegroups.com:

> On 6 Sep, 18:09, Artemisia <[email protected]> wrote:
>> [...]
>
> According to wikipedia:
>
> "On firm, flat, ground, a 70 kg man requires about 100 watts to walk
> at 5 km/h. That same man on a bicycle, on the same ground, with the
> same power output, can average 25 km/h, so energy expenditure in terms
> of kcal/kg/km is roughly one-fifth as much."
>
> http://en.wikipedia.org/wiki/Bicycle_performance
>
> I've found other references on the same lines that suggest that
> calories per hour for cycling and walking are about the same. [1] One
> said walking used 25% more; this site
>
> http://www.coolnurse.com/calories.htm
>
> suggests that per minute, cycling uses more calories than walking. It
> also says the difference is greater if you weigh more.

The reference to use is The Compendium of Physical Activities which can be
downloaded from http://prevention.sph.sc.edu/tools/compendium.htm. This
uses METs which are 1 kcal/kg/hr so you have to multiply by your weight and
normalise for speed to get the answer. Walking is about 3.0 METs and
cycling 4-8 but the cycling speed means per mile cycling wins big time
while per hour walking wins (although you don't go nearly as far).


--
Tony

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

 

[Peter Clinch]

Artemisia 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?

You need to be very careful with what the terms mean. "Efficiency" can
mean all sorts of things but it'll typically be which uses least energy.
And cycling will very, very probably use less energy *but* that's not
all there is to it... You have to take into account stuff like your
cycling muscles may well be past their best (because you've just done
75% of a bloody great hill) and a change can be as good as a rest.

> 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...

No, it'll generally be better, but there will be times when you just
/can't/ keep up the pedalling (can be tiredness, maybe you just be
bothered any more) and a short walk to top out is the easiest way to
finish the job, if not in absolute energy terms but which feels
subjectively best for your body at the time.

Try not to think in such black and white terms. Cycling and walking
have their places and there are lots of interlocking variables that
determine which is right at the time: how tired you are, how much of a
hurry you're in, how big is the particular hill, how hot is the day etc.
etc.

In the example this sub-thread spins out from I could have finished the
job on the bike and would probably have used less net energy. But I
just couldn't be /bothered/ with it any more.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email protected] http://www.dundee.ac.uk/~pjclinch/

 

[Alan Braggins]

In article <[email protected]>, Tony Raven wrote:
>The reference to use is The Compendium of Physical Activities which can be
>downloaded from http://prevention.sph.sc.edu/tools/compendium.htm. This
>uses METs which are 1 kcal/kg/hr so you have to multiply by your weight and
>normalise for speed to get the answer. Walking is about 3.0 METs and
>cycling 4-8 but the cycling speed means per mile cycling wins big time
>while per hour walking wins (although you don't go nearly as far).

Except the question was in response to a scenario where Pete walking
his bike had overtaken his friend riding in the lowest available gear.
We all know cycling is more efficient in general, the question was whether
that's still true on steep uneven ground where walking may be quicker.

 

[Tony Raven]

[email protected] (Alan Braggins) wrote in
news:[email protected]:

> In article <[email protected]>, Tony Raven wrote:
>>The reference to use is The Compendium of Physical Activities which
>>can be downloaded from
>>http://prevention.sph.sc.edu/tools/compendium.htm. This uses METs
>>which are 1 kcal/kg/hr so you have to multiply by your weight and
>>normalise for speed to get the answer. Walking is about 3.0 METs and
>>cycling 4-8 but the cycling speed means per mile cycling wins big time
>>while per hour walking wins (although you don't go nearly as far).
>
> Except the question was in response to a scenario where Pete walking
> his bike had overtaken his friend riding in the lowest available gear.
> We all know cycling is more efficient in general, the question was
> whether that's still true on steep uneven ground where walking may be
> quicker.
>

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.

--
Tony

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

 

[Peter Clinch]

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.

I think that's already been accepted and understood here. The point is
that when you throw rough ground into the equation there is a lot of
inefficiency thrown in to the cycling because the bike and rider has to
spend a lot of power moving up and down as well as along (why a full sus
bike is faster downhill with the gravitational acceleration than a
rigid, but it doesn't work so well when climbing at very low speed).

The question is, is that up-and-down loss of efficiency bigger than the
inherent inefficiency of walking. Since this was a grass field which
isn't all that /rough/, I would suspect not in this case, but OTOH the
grass gives a lot more friction to a constantly contacting bike wheel
than a walker's feet which are typically above it for almost the whole time.

I don't know. I suspect it's not the straightforward answer of a smooth
road though (but on that smooth road again the messy Real World caveat
that you can only burn energy at /any/ efficiency if the relevant
muscles are still up to it, and if your cycling muscles are knackered
and the walking ones aren't that could be a moot point).

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email protected] http://www.dundee.ac.uk/~pjclinch/

 

[[email protected]]

On Sep 7, 6:33 pm, Tony Raven <[email protected]> wrote:
> "[email protected]" <[email protected]> wrote innews:[email protected]:
>
>
>
> > On Sep 7, 2:38 pm, Tony Raven <[email protected]> wrote:
> >> Artemisia <[email protected]> wrote
> >> innews:[email protected]:
>
> >> > Tony Raven wrote:
>
> >> >> Cycling is a more efficient way of moving than walking so cycling
> >> >> up will use less energy
>
> >> > Is cycling more efficient than walking under all circumstances? Are
> >> > you speaking from experience?
>
> >> No I'm speaking from the research evidence. Walking takes about 40%
> >> more calories per mile than cycling for commuting and the difference
> >> can be much more. If you had a really heavy bike it might equal
> >> things out a bit on a hill but it would have to be really
> >> heavy.http://ffden-2.phys.uaf.edu/211.fall2000.web.projects/J%
> >> 20Krizek/humanpower%20page%203.html
>
> > But you are assuming that the "research evidence" about general
> > cycling (including level and downhill riding) also applies to the
> > specific case of cycling up a steep hill. Clearly there are such large
> > and fundamental differences in the physics that this hypothesis is at
> > best...a hypothesis. It's not an implausible null hypothesis when the
> > slope is reasonably shallow and the surface firm, but I don't see any
> > reasonable basis for it in steep and soft conditions (and anecdotal
> > evidence suggests it is wrong).
>
> > In soft mud (or sand, see below) there is no question that cycling can
> > be harder work, even on the level. Again, that is exactly as expected
> > from simple physical principles.
>
> >http://www.japanprobe.com/?p=2585
>
> Yes I am sure you can come up with all sorts of scenarios - boulder
> fields, scree slopes, deep snow, overhanging rock faces.... where cycling
> is less efficient than walking but that was not the tenor of the original
> question not did I feel it necessary to caveat every possibility in my
> original reply. But please feel free to point out my omissions.

The first obvious omission is the weight of the bicycle (as you admit
below) which is a significant penalty for the cyclist, and the second
one is the possible softness of the ground which on a grassy field
where a walker overtakes a cyclist seems hard to ignore!

>
> Meanwhile perhaps you could elucidate for us what the "large and
> fundamental differences in the physics" (other than the weight of the
> bike) are and why the angle of a typical road surface should reverse the
> efficiency relationship between cycling and walking.

as I've mentioned, the original poster was specifically talking about
off-road cycling. I repeat here for your edification:
---
On Sep 7, 2:09 am, 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 really find it hard to believe that an intelligent and experienced
off-road cyclist could seriously dispute that in the situation as
described, it may indeed be more energy efficient to walk.

James