More distance per Calorie: Walk vrs Granny Gear Uphill?

[[email protected]]

On Sep 9, 3:47 am, [email protected] (Tom Keats) wrote:
> In article <[email protected]>,
> [email protected] writes:
>
> > Dear Artemisia,
>
> > I suspect that rider would go much faster up Fargo Street if he simply
> > walked up it, pushing his bike, with the same amount of effort--he's
> > heaving with all his might with every pedal stroke, barely able to
> > keep the pedals moving past the dead spots.
>
> ^^^^^^^^^^
>
> What causes those "dead spots" anyways?
>
> Is it physiological, or mechanical, or both,
> or neither?
>
> If (the legs of) a rider going up a steep grade
> experiences dead spots, it occurs to me that the
> drivers on a steam locomotive going up a steep
> grade might also experience similar dead spots.
>
> Anyways, I rather dislike those dead spots.
>
> cheers,
> Tom
>
> --
> Nothing is safe from me.
> I'm really at:
> tkeats curlicue vcn dot bc dot ca

Dear Tom,

Utterly off topic, but you mentioned locomotives and dead spots . . .

So here's a post about an 1894 steam-powered bicycle with a locomotive-
style transmission, complete with movie of a reconstruction chugging
along:

http://groups.google.com/group/rec.bicycles.tech/msg/2588df400d5ced14

Ch-ch-ch-cheers,

Carl Fogel

 

[Ben C]

On 2007-09-12, Rob Morley <[email protected]> wrote:
> 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.

Or a fixed-gear bike.

 

[[email protected]]

On Sep 10, 3:42 pm, [email protected] wrote:

> Our legs have no natural flywheel action and stop spinning as soon as
> we stop trying to pedal--it takes constant power to churn those big
> chunks of meat and bone up and donwn.

But obviously very very little power, as anyone who has ever broken a
chain or dropped a gear will know. It also takes power to lift a foot
up higher than ground level only to put it down again when walking.
Which do you think is a greater waste of power, and why? Have you any
quantitative estimates of either effect on which to base a comparison?

James

 

[Rob Morley]

In article <[email protected]>, Ben C
[email protected] says...
> On 2007-09-12, Rob Morley <[email protected]> wrote:
> > 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.
>
> Or a fixed-gear bike.
>
What that does is use the flywheel effect of the rear wheel to pull your
legs past the dead spot, which you don't need anyway if you pedal in
circles rather than squares. What fixed wheel does not do is smooth the
power delivery to the wheel.

 

[POHB]

On 11 Sep, 01:36, [email protected] wrote:
> > > 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.

I think your reasoning is flawed as it assumes that walking efficiency
is constant for all speeds. Actually at zero speed walking is also
100% inneficient as you are spending energy keeping upright but making
no forward movement. As walking speed increases the efficiency also
increases, the same as cycling.

So, the question is how the two efficiency curves compare to each
other. If you plot efficiency on an increasing Y axis and speed on X,
which curve takes off most steeply and where (if ever) do they cross.
The concensus seems to be that the walking curve starts off more
steeply but the cycling curve crosses it at about normal walking pace
and then continues upwards.

 

[[email protected]]

On Sep 12, 1:22 am, "[email protected]" <[email protected]>
wrote:
> On Sep 10, 3:42 pm, [email protected] wrote:
>
> > Our legs have no natural flywheel action and stop spinning as soon as
> > we stop trying to pedal--it takes constant power to churn those big
> > chunks of meat and bone up and donwn.
>
> But obviously very very little power, as anyone who has ever broken a
> chain or dropped a gear will know. It also takes power to lift a foot
> up higher than ground level only to put it down again when walking.
> Which do you think is a greater waste of power, and why? Have you any
> quantitative estimates of either effect on which to base a comparison?
>
> James

Dear James,

Dear James,

Let's consider a 33.3% grade and a rider whose weight and fitness
reduce him to using 1-to-1 overall gearing.

Obviously, some riders would need more gearing and others could use
higher gearing, but we need a specific example, and most posters would
consider a mile of 33.3% grade steep.

There are two ways to calculate slope as a percentage. In this case,
we mean a 33% grade where you gain 1 foot in height for every 3 feet
that you move forward and upward as measured by an odometer.

The other method of calculating slope as a percentage would gain 1
foot in height for every 3 _level_ feet forward and would call our
slope a 35.3% grade (1 / 2.83) instead of 33% (1 / 3.00). This
wouldn't matter much to the overall calculations, but it's best to
avoid confusion.

With 1-to-1 overall gearing, the foot travels just as far around the
pedal circle as the rear wheel moves forward. For a 2100 mm 700c tire
and a 175 mm crank, this means 20 x 38 gearing and a 350 mm high pedal
circle.

Pi * 350 mm gives an 1100 mm "stride" with each pedal cycle.

In other words, for each 1.1 meters up the 33.3% grade, you turn a
full pedal cycle, raising and lowering your left foot 350 mm relative
to its initial bottom dead center position on the 175 mm crank.

Here's a diagram with numbers:

http://i6.tinypic.com/6crrg3n.jpg

Half-way up the 1100 mm slope, the whole bicycle has risen 183 mm,
which is 33.3% of 550 mm.

Meanwhile, the left pedal has risen another 350 mm, from the bottom to
the top of the pedal cycle, so the pedal is 533 mm above its starting
position (183 + 350 = 533 mm total rise).

Then the left pedal descends back to the bottom of the pedal cycle,
reaching bottom dead center again at 1100 mm up the slope and dropping
166 mm from 533 mm down to 367 mm, which is 33.3% of 1100 mm.

In other words, the left foot rises much more sharply than the slope
for the first part of the pedal cycle.

Then it drops more gently about 6.5 inches from its highest point,
roughly the height of a stair step.

When walking, most people don't lift their feet as high as the step
_above_ the step that they plant their foot on, unless they're doing a
very strange goose-step.

Cheers,

Carl Fogel

 

[Tony Raven]

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

> In other words, the left foot rises much more sharply than the slope
> for the first part of the pedal cycle.
>
> Then it drops more gently about 6.5 inches from its highest point,
> roughly the height of a stair step.
>
> When walking, most people don't lift their feet as high as the step
> _above_ the step that they plant their foot on, unless they're doing a
> very strange goose-step.

Dearest Carl,

You've forgotten a significant factor in your estimations that makes your
conclusions wrong. When you lift your foot walking it takes energy to
do it. When you put it back down you don't regain that energy. On a
bicycle its different. The cranks are neutrally balanced if the weight
of your legs is the same. So when your left foot is going down, the
potential energy lost from its weight descending on the pedal is
transferred through the cranks to lift the weight of the right leg up.
To first order the energy expended in that revolution of the pedals is
only the energy needed to move the bike and rider up the slope and the
energy needed to overcome the friction in the bottom bracket and chain.
The energy component from the legs going round and round is to first
order negligible.

--
Tony

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

 

[Ben C]

On 2007-09-13, Tony Raven <[email protected]> wrote:
> [email protected] wrote in
> news:[email protected]:
>
>> In other words, the left foot rises much more sharply than the slope
>> for the first part of the pedal cycle.
>>
>> Then it drops more gently about 6.5 inches from its highest point,
>> roughly the height of a stair step.
>>
>> When walking, most people don't lift their feet as high as the step
>> _above_ the step that they plant their foot on, unless they're doing a
>> very strange goose-step.
>
> Dearest Carl,
>
> You've forgotten a significant factor in your estimations that makes your
> conclusions wrong. When you lift your foot walking it takes energy to
> do it. When you put it back down you don't regain that energy. On a
> bicycle its different. The cranks are neutrally balanced if the weight
> of your legs is the same. So when your left foot is going down, the
> potential energy lost from its weight descending on the pedal is
> transferred through the cranks to lift the weight of the right leg up.

I'm not sure about this argument.

When you walk up steps you lift your leg up and then push down on the
step with it. The fact that your leg has weight means that you can push
down a little bit less hard. So you get the potential energy back in
spite of not having neutrally balanced cranks.

Actually of course your leg isn't really falling, if you're walking up
steps, but staying roughly where it is, while the rest of your body is
lifted up to join it on the next step. This doesn't really change
anything though: first you lift one leg to put it on the step in front
of you. Then you lift the weight of your body minus the weight of that
one leg to heave the rest of you up the step. So altogether you lifted
your whole weight up the step once, in two stages. No wasted lifting, at
least not in this basic picture of what's happening.

Another way of looking at it is this: suppose you rode the bike in such
a way that you lifted the up-leg with its own muscles instead of
allowing it to be pushed up by the pedal-- so on the upstroke your foot
hovered a tiny distance above the pedal at all times. Although you'd
have to put in a bit more energy to lift that leg, the leg that was
going down would go down with more force: whatever you were pushing with
_plus its own weight_. What you take from the up leg you give back to
the down leg. Whether the leg lifts itself or is lifted by the other leg
makes no difference, and for the purposes of the point being made here,
walking is just the same as cycling with up-leg self-lifting.

I'm not sure about Carl's argument either though. If you walk up steps
it doesn't make any difference to the energy expended as far as the
basic physics are concerned how high or shallow the steps are.

If walking up a slope is easier than riding up it (for the same weight,
Carl's 1:1 gear, etc.) then I think we need to look somewhere else for
the reason.

 

[Tony Raven]

Ben C <[email protected]> wrote in
news:[email protected]:

>
> I'm not sure about this argument.
>
> When you walk up steps you lift your leg up and then push down on the
> step with it. The fact that your leg has weight means that you can
> push down a little bit less hard. So you get the potential energy back
> in spite of not having neutrally balanced cranks.

That would be if you slid your foot onto the step but you don't, you lift
it above the step and then put it down. Likewise walking up a slope you
don't slide your foot up the slope but lift it off the surface, move it
up and then put it down again. Its the putting down bit that wastes
potential energy that is not wasted on a bike.

>
> I'm not sure about Carl's argument either though. If you walk up steps
> it doesn't make any difference to the energy expended as far as the
> basic physics are concerned how high or shallow the steps are.
>

It will matter unless the distance you lift your foot above the step
before putting it down is proportional to the step height. It is more
likely to be the same distance irrespective of the step height in which
case the energy lost will be inversely proportional to the height of the
step (because it will take more steps to climb a given height so the
energy lost will be the loss per step times the number of steps for a
given height).

--
Tony

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

 

[Ben C]

On 2007-09-13, Tony Raven <[email protected]> wrote:
> Ben C <[email protected]> wrote in
> news:[email protected]:
>
>>
>> I'm not sure about this argument.
>>
>> When you walk up steps you lift your leg up and then push down on the
>> step with it. The fact that your leg has weight means that you can
>> push down a little bit less hard. So you get the potential energy back
>> in spite of not having neutrally balanced cranks.
>
> That would be if you slid your foot onto the step but you don't, you lift
> it above the step and then put it down. Likewise walking up a slope you
> don't slide your foot up the slope but lift it off the surface, move it
> up and then put it down again. Its the putting down bit that wastes
> potential energy that is not wasted on a bike.

I see what you're saying, yes. This could be mitigated by springy shoe
soles (I mean literally springy). You'd only need a slight spring in
them so it wouldn't feel like walking on a trampoline.

All the same, I don't think it's very much energy or that we need
springy shoes. Not that anyone was claiming that it was.

>> I'm not sure about Carl's argument either though. If you walk up steps
>> it doesn't make any difference to the energy expended as far as the
>> basic physics are concerned how high or shallow the steps are.
>>

> It will matter unless the distance you lift your foot above the step
> before putting it down is proportional to the step height. It is more
> likely to be the same distance irrespective of the step height in
> which case the energy lost will be inversely proportional to the
> height of the step (because it will take more steps to climb a given
> height so the energy lost will be the loss per step times the number
> of steps for a given height).

For walking yes. But just to clarify: for cycling, you get it all back
anyway so it doesn't matter that you're lifting your legs a bit higher.
This is what you said in the first place.

 

[[email protected]]

On Sep 14, 4:15 am, [email protected] wrote:
> On Sep 12, 1:22 am, "[email protected]" <[email protected]>
> wrote:
>
> > On Sep 10, 3:42 pm, [email protected] wrote:
>
> > > Our legs have no natural flywheel action and stop spinning as soon as
> > > we stop trying to pedal--it takes constant power to churn those big
> > > chunks of meat and bone up and donwn.
>
> > But obviously very very little power, as anyone who has ever broken a
> > chain or dropped a gear will know. It also takes power to lift a foot
> > up higher than ground level only to put it down again when walking.
> > Which do you think is a greater waste of power, and why? Have you any
> > quantitative estimates of either effect on which to base a comparison?
>
> > James
>
> Dear James,

[...]

> When walking, most people don't lift their feet as high as the step
> _above_ the step that they plant their foot on, unless they're doing a
> very strange goose-step.

So aside from writing down lots of rather arbitrary numbers, do you
actually have any evidence - or can you even produce a meaningful
quantitative estimate - of the supposed inefficiency of the pedalling
motion?

James

 

[Tom Keats]

In article <[email protected]>,
Ryan Cousineau <[email protected]> writes:
> In article <[email protected]>,
> [email protected] (Tom Keats) wrote:
>
>> In article <[email protected]>,
>> Ryan Cousineau <[email protected]> writes:

>> > Change out your 6-speed for a 7-speed Megarange.
>>
>> Who's got 'em? Everywhere I've gone when needing to
>> update my freewheel, only has those steenkin' 6-spd
>> 14-28s. Sometimes I feel like drop-kickin' 'em into
>> the next universe (or at least, Burnaby.) No doubt
>> they'd eventually return by similar means.
>
> !? Hm. Try phoning Sports Junkies in Port Moody,

I'd rather ride to there. There's this barber shop
on St Johns that does pretty good haircuts anyways.

> and if Bikes on the
> Drive doesn't have it, they're missing their market.
>
> Otherwise, the Internet has lots of them.
>
> But that's weird: the 11-34 7s should be one of the most common
> freewheels around.

The irony is, I'm fixing-up a foundling DiamondBack
Sorrento with one of those on it. I guess its OEM
stuff on the bike, and the luck o' the draw for me,
trying to get replacement components.

IME, the 14-28 6's are much more ubiquitous.
Oh, well -- they're the devil I know, anyway.

Maybe I'm predestined to not have those comfortably
low gears with which one can speed past walkers up
15%+ grades?

Maybe that's like Lonsdale Ave in North Van.
Ooooh, I hate that odius climb. And not just
because of its steepness, but the crass, surrounding
environment. It's like Kingsway on a mountainside.
It's so very anti-inspiring. But there's used to
be a 7-Eleven up there, just across from the KFC,
that's been one of my luckiest Lotto 6/49 sources.
It's been a while since I've been up that way; I
don't know if those establishments still exist.

Yeah, those MegaRanges are around. Synchronicity
just denies me them. Every time I seek & need 'em,
all they've got are 14-28 6's. And Z-Chains


cheers,
Tom

--
Nothing is safe from me.
I'm really at:
tkeats curlicue vcn dot bc dot ca

 

[Artemisia]

Tom Keats wrote:
> But there's used to
> be a 7-Eleven up there, just across from the KFC,
> that's been one of my luckiest Lotto 6/49 sources.

So like a Sagittarian to be lucky at Lotto!

EFR
Ile de France

 

[CoyoteBoy]

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?
>
> 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

Was there a conclusion to this thread? Did anyone find evidence that
cycling at walking pace is in fact harder than walking at walking
pace? I only ask as a friend with back problems ends up in severe pain
trying to walk more a distance with his wife, but needs to do the same
quantity of exercise - I was trying to work out if cycling next to his
wife would pose the same energy/heart rate requirements etc and so be
equally beneficial. I know cycling in a straight line is extremely
easy in the granny ring at walking pace but then i dont find walking
hard either so i cant judge, im sure that after 3 miles of granny-ring
riding I'd be knackered lol.

 

[[email protected]]

On Sep 15, 10:58 pm, CoyoteBoy <[email protected]> wrote:

> Was there a conclusion to this thread? Did anyone find evidence that
> cycling at walking pace is in fact harder than walking at walking
> pace?

Nope, at least not on a road surface under plausible real world
conditions.

>I only ask as a friend with back problems ends up in severe pain
> trying to walk more a distance with his wife, but needs to do the same
> quantity of exercise - I was trying to work out if cycling next to his
> wife would pose the same energy/heart rate requirements etc and so be
> equally beneficial. I know cycling in a straight line is extremely
> easy in the granny ring at walking pace but then i dont find walking
> hard either so i cant judge, im sure that after 3 miles of granny-ring
> riding I'd be knackered lol.

You may have misunderstood the discussion. i don't think anyone ever
suggested that cycling at walking pace *on reasonably level ground*
would require similar effort to walking - the discussion was concerned
with climbing steep hills. Your friend will get almost no exercise
from this approach unless their route is a very steep one, and he may
find it awkward trying to go slowly enough.

When I had a slipped disk a few years ago, I could cycle much more
easily than walk. But I had no reason to travel at 3mph

James

 

[peter]

On Sep 15, 6:58 am, CoyoteBoy <[email protected]> wrote:

> Was there a conclusion to this thread? Did anyone find evidence that
> cycling at walking pace is in fact harder than walking at walking
> pace? I only ask as a friend with back problems ends up in severe pain
> trying to walk more a distance with his wife, but needs to do the same
> quantity of exercise - I was trying to work out if cycling next to his
> wife would pose the same energy/heart rate requirements etc and so be
> equally beneficial.

They'll only be close to the same effort when going up a very steep
hill. When climbing hills of 30% grade or more, walkers/runners and
cyclists of similar fitness go up at about the same speed - both very
slowly. That may not help your friend much since paved surfaces that
are that steep aren't all that common and neither he nor his wife may
find such a climb enjoyable on a regular basis.

 

[Rob Morley]

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

> Was there a conclusion to this thread? Did anyone find evidence that
> cycling at walking pace is in fact harder than walking at walking
> pace? I only ask as a friend with back problems ends up in severe pain
> trying to walk more a distance with his wife, but needs to do the same
> quantity of exercise - I was trying to work out if cycling next to his
> wife would pose the same energy/heart rate requirements etc and so be
> equally beneficial.

What he needs is one of those bikes with hydraulic transmission.

 

[CoyoteBoy]

On 16 Sep, 02:53, Rob Morley <[email protected]> wrote:
> In article <[email protected]>,
> CoyoteBoy
> [email protected] says...
>
> > Was there a conclusion to this thread? Did anyone find evidence that
> > cycling at walking pace is in fact harder than walking at walking
> > pace? I only ask as a friend with back problems ends up in severe pain
> > trying to walk more a distance with his wife, but needs to do the same
> > quantity of exercise - I was trying to work out if cycling next to his
> > wife would pose the same energy/heart rate requirements etc and so be
> > equally beneficial.
>
> What he needs is one of those bikes with hydraulic transmission.

The other option was a turbo trainer but it would have been nicer to
have the exercise outside with his wife

 

[CoyoteBoy]

On 16 Sep, 00:04, "[email protected]" <[email protected]>
wrote:
> On Sep 15, 10:58 pm, CoyoteBoy <[email protected]> wrote:
>
> > Was there a conclusion to this thread? Did anyone find evidence that
> > cycling at walking pace is in fact harder than walking at walking
> > pace?
>
> Nope, at least not on a road surface under plausible real world
> conditions.
>
> >I only ask as a friend with back problems ends up in severe pain
> > trying to walk more a distance with his wife, but needs to do the same
> > quantity of exercise - I was trying to work out if cycling next to his
> > wife would pose the same energy/heart rate requirements etc and so be
> > equally beneficial. I know cycling in a straight line is extremely
> > easy in the granny ring at walking pace but then i dont find walking
> > hard either so i cant judge, im sure that after 3 miles of granny-ring
> > riding I'd be knackered lol.
>
> You may have misunderstood the discussion. i don't think anyone ever
> suggested that cycling at walking pace *on reasonably level ground*
> would require similar effort to walking - the discussion was concerned
> with climbing steep hills. Your friend will get almost no exercise
> from this approach unless their route is a very steep one, and he may
> find it awkward trying to go slowly enough.
>
> When I had a slipped disk a few years ago, I could cycle much more
> easily than walk. But I had no reason to travel at 3mph
>
> James

I didnt really misunderstand the OP, more I was trying to drag more
out of it than originally was asked lol. The route is off-road and
fairly hilly but not very hilly. The friend has 2 compressed and
slipped lower discs and 3 vertebrae fused in his neck and has put up
with them as-is for longer than I care to think about, despite being
in agony silently. The problem is having recently had a heart problem
he has been told he needs to exercise (he isnt fat, just not fit) and
walking is leaving him in a lot of pain, so he is just avoiding
exercise all together - not ideal. Anything would be better than
nothing. I was going to loan my bike out as and when he needs it
(right size, give or take moving the saddle a smidge). I suppose his
wife could get her bike out too in order to have them both doing a
half-decent pace, but this is going to be a mammoth task to get them
both interested lol!

 

[CoyoteBoy]

On 16 Sep, 00:40, peter <[email protected]> wrote:
> On Sep 15, 6:58 am, CoyoteBoy <[email protected]> wrote:
>
> > Was there a conclusion to this thread? Did anyone find evidence that
> > cycling at walking pace is in fact harder than walking at walking
> > pace? I only ask as a friend with back problems ends up in severe pain
> > trying to walk more a distance with his wife, but needs to do the same
> > quantity of exercise - I was trying to work out if cycling next to his
> > wife would pose the same energy/heart rate requirements etc and so be
> > equally beneficial.
>
> They'll only be close to the same effort when going up a very steep
> hill. When climbing hills of 30% grade or more, walkers/runners and
> cyclists of similar fitness go up at about the same speed - both very
> slowly. That may not help your friend much since paved surfaces that
> are that steep aren't all that common and neither he nor his wife may
> find such a climb enjoyable on a regular basis.

It would be off-road riding through the local fields, but not very
steep. Probably 15 degrees or so for a short period but generally
fairly flat after that. I'll see if i can get them both on bikes