More distance per Calorie: Walk vrs Granny Gear Uphill?

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

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?

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.

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Artemisia wrote in
:

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

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

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.

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?

On Sep 7, 2:38 pm, Tony Raven 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?

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.fall...eb.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

On 6 Sep, 18:09, 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?

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.

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

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

Tony Raven wrote:

Artemisia wrote in
:

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