Efficiency of walking v riding up a hill

[pharmaboy]

Why are you asking? Are you looking for the most efficient way to the top as far as calories go? Or are you racing and looking for the fastest way to the top?

Isn't speed and efficiency pretty much the same thing? Doesn't matter whether I'm running or riding I'll be in vo2 area.

But 1. It's for interest sake, mechanical advantage declines going up a hill, sooner or later it crosses where the weight of the bike is a negative and no longer a help.

2 it does influence gearing choices. Eg is it worthwhile to have a 22 ...36 combo if that is just the same speed / efficiency as walking up.

Even more relevant for 11speed peoples - is it worth getting the 28 front for the loss of huge top end speed?

 

[johnny]

You have missed the fact that in the bike example the mass we are trying to get up the hill in both cases [riding and walking] has the mechanical advantage of being under wheels
In your example the mass of the cube and the sphere may be the same but the sphere clearly has an advantage when you are pushing/rolling it up the hill because you are not fitting the friction that the cube has just sliding

But that's the whole point. Your premise is same mass up same slope by same person = same energy.

However issues such as friction and leverage are going to have an effect on the equation. Another example would be - pushing a bike up the hill normally and pushing the same bike up the same hill with the breaks on. Same mass, same method but more energy needs to be used when the breaks are on because of friction. That suggests the premise of same mass/hill/person = same energy cannot be right.

Your answer of same energy for walking as to riding might be correct, however your premise of same mass/hill/person being the applicable equation is not.


Now I'm way out of my depth in this field, so, please, be gentle!!

 

[No Skid Marks]

There's no clear answer becaus there's no clear question. Traction, trail surface, tyre width and pressures, bike design, length of hill, length of overall ride, fitness,pitch and many other components play into it.
pick a hill walk with bike then ride it, repeats in reverse the following day, you'll quickly get an answer for THAT hill alone.
IMO as a gross generalization not considering most of the details above.short hill walk, long hill ride is theost efficient. Or a mix of both. My body tells me pretty accurately. Always different.

 

[SlowManiac]

I reckon this is pretty much impossible to answer without taking into account a variety of factors - how technical is the climb, how good a cyclist vs fitness as a walker, even geometry of the bike, HT vs DS, there are so many variables.

I always ask myself: can I ride it?

if yes: am I going to blow myself up by riding or trying to ride?

if yes: get off and walk.

 

[pistonbroke]

If you are racing and looking for the fastest way up a hill I would stay on the bike if you can. I think if you get off and walk 2 things will happen.
1. You'll ride as far as you can and then stop, get off and start walking.
2. You'll get to the top, stop and get back on the bike.
My point? You've stopped twice which slows you down. I also find getting on and off the bike quite taxing when I'm deep into the hurt locker. If I can, I'd rather stay on and pedal.

 

[Jesterarts]

The same mass up the same slope at the same constant speed covering the same distance in the same amount of time = the same energy expenditure. Walk or ride take your pick cause you will be just as knackeredd at the top

Almost correct, the thing that is missing from this statement is consideration for gears and their impact on the engine (ie the persons) exhersion.

Think about it, when you go up hill you shift to a lower gear. Why? Because it's easier.

Even if we are talking moving up the hill at the same speed in once gear it may be near impossible while in a lower gear it is easier.

Personally, I find I am more tired at the top of a hill riding up than I am walking.

This could be due to having plush suspension so some of the energy I exert pedaling is used up bouncing up and down.

Moral of the story, need a shuttle.

 

[No Skid Marks]

There's no clear answer becaus there's no clear question. Traction, trail surface, tyre width and pressures, bike design, length of hill, length of overall ride, fitness,pitch and many other components play into it.
pick a hill walk with bike then ride it, repeats in reverse the following day, you'll quickly get an answer for THAT hill alone.
IMO as a gross generalization not considering most of the details above.short hill walk, long hill ride is theost efficient. Or a mix of both. My body tells me pretty accurately. Always different.

 

[harmonix1234]

There is only one answer to this question.

Tomac.

 

[Mywifesirrational]

This is a good question; without a specific answer I'd think.

One way to test this for yourself is pick a decent climb and walk it while pushing the bike and ride it, time both events.
Most importantly wear a heart rate monitor while you do both. HR has a very predictable and linear relationship with energy expenditure.
Take the total HR for both events correlate it off the time it took to complete the climb and you'll have a fairly decent answer.

I'm going for walking uphill (steep and a bonus if it is rough) is more energy efficient than riding, bipedal locomotion is the most efficient form of getting from A to B there is on uneven terrain.
Fitness and specificity would also play a role - an elite level cyclist will do it easier than walking, while a mountain runner would probably leave them for dead (at the same HR).

 

[richie_gt]

I would assume to effectively measure efficiency you'd want events to have the same time, then measure the energy used by each method and compare.

i.e. to get up the hill in '5 minutes' is it more efficient to walk, or ride up the hill?

 

[paulb]

It all depends. Theoretical physics wise the energy is always the same, but that doesn't mean you can run instead of walk and use the same subjective energy.

I've 'raced' a single speed in the past, including the first dirt works 100, but mostly ride geared bikes now.

I find getting off and walking tightens up my calves so given a rideable gear I'll normally prefer to ride.

But especially in race conditions, you shouldn't bust yourself riding until you can't. I can remember a Mont at Majura on the SS where every lap I walked up a hill and then overtook almost everyone who'd ridden past on the climb because they didn't have the energy to get full speed in the next section. You should manage your energy for where it counts.

And if you walk, hold the bike by the stem and walk upright. Hunched over leaning on the bike is no good long term. I learnt this at the Dirt Works 100km

 

[thecat]

logic being the they both have moved the same MASS at the same speed over the same distance.

You are neglecting to factor in mechanical advantage

These numbers are a bit old so may not be completely actuate anymore but according to Ivan Illich on foot a human expends 0.75calories per gram to move 1km in 10 min over flat ground. On a bike, in a reduced time (can't remember exactly) it comes down to as low as 0.15 calories per gram.

So the idea of same mass, same distance, same speed = same calories is completely bunk.

On flat ground you use approximately 1/5th of the calories to cover the same distance in a quicker time. The steeper a hill gets the less pronounced the difference will become but until it gets vertical (or you start lossing traction) you will still use less calories on the bike (Given effiecient pedaling technique and suspension set up and all the rest)

Besides If i'm on a big ride and have been turning the pedals over at a constant rate for a long time the sudden difference in getting of and trying to run/walk is a sure way to spark the twinges of on coming cramp

 

[pharmaboy]

Bit more real world data, at a17% offroad grade, I found a segment where the KOM averaged 4kmh, while the 2nd and third runner ( ignored the CR because he was way faster) ran at 6.5kmh.

So at 10% real world! cycling by maybe 20% faster! by 17%, you are way slower on a bike

Google found
http://www.ncbi.nlm.nih.gov/m/pubmed/12898263/

Abstract
On level ground, cycling is more economical than running, which in turn is more economical than walking in the high speed range. This paper investigates whether this ranking still holds when moving on a gradient, where the three modes are expected to be mainly facing the same burden, i.e. to counter gravity. By using data from the literature we have built a theoretical framework to predict the optimal mode as a function of the gradient. Cycling was found to be the mode of choice only below 10-15% gradient, while above it walking was the least expensive locomotion type. Seven amateur bikers were then asked to walk, run and ride on a treadmill at different gradients. The speed was set so as to maintain almost constant the metabolic demand across the different gradients. The results indicate that the "critical slope", i.e. the one above which walking is less expensive than cycling (and running), is about 13-15%. One subject was loaded during bipedal gaits with a bicycle-equivalent mass, to simulate to cross-country cycling situation. The critical slope was close to 20%, due to the higher metabolic cost of loaded walking and running. Part of the findings can be explained by the mechanically different paradigms of the three locomotion types.

 

[casnell]

But the runners weren't pushing a 10 kg bike?

 

[oldstinky75]

I always ask myself: can I ride it?

if yes: am I going to blow myself up by riding or trying to ride?

if yes: get off and walk.[/QUOTE]

Badda bing badda boom

End thread

 

[Jim Junkie]

But the runners weren't pushing a 10 kg bike?

/Snip
The results indicate that the "critical slope", i.e. the one above which walking is less expensive than cycling (and running), is about 13-15%. One subject was loaded during bipedal gaits with a bicycle-equivalent mass, to simulate to cross-country cycling situation. The critical slope was close to 20%, due to the higher metabolic cost of loaded walking and running. Part of the findings can be explained by the mechanically different paradigms of the three locomotion types.

Looks like they did something along those lines with one unlucky dude, with increased the grade at which the tipping point occurred to 20%.

Not perfect as you miss all the bio-dynamics, but representative that it does have an impact at least.

Good article, I knew someone at least had to have been curious enough to conduct a study.

 

[Jubas]

I would have thought that walking up a steep slope was more efficient than trying to ride it in a granny - primarily because when riding you're having to expend energy keeping the bike balanced (i.e. upright) and having your weight distributed properly (i.e. keeping front wheel down, smooth pedal strokes etc). For me at least, that takes up more energy than balancing with two legs + two wheels on the ground (I.e. walking). I'm always having to fight too much tension while climbing on the bike which I know expends energy!

 

[Ridenparadise]

My shitty XC shoes slip like crazy when I walk uphill, my heels lift out of the heel pocket and my cleats wear out. Win for riding. However, some days it's just a pain to ride up steep climbs and better to walk and talk with my SS riding buddy.

All this makes me think I need a 29er, rigid fatbike, or an electric MTB. I didn't get into MTB to work hard.

 

[granto]

Ride > Walk

Your are a MTBer. You have a MTB. Ride it (if at all possible).

Walking's for cyclocrosser's.

 

[outtacontrol]

Fuck the science. If I push up a steep hill or trail, I can hop on and ride at the top. If I bust my arse riding it I spend the next 10 minutes once I reach the top trying not to vomit.

Case closed...