At what Gradient Does it Becomes pointless Riding up a Hill?

At what Gradient Does it Becomes pointless Riding up a Hill?

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Discussion

bagusbagus

Original Poster:

470 posts

94 months

Sunday 22nd November 2020
quotequote all
From purely physics, when does riding a bike up a hill starts getting ''pointless'' in the energy being used compared to just walking with the bike up a hill?

Ie. When do the amounts of energy burned becomes same , also is there a situation/ a hill steep enough where riding a bike up a hill can actually be Less efficient than just walking and pushing the bike up the hill?

LordHaveMurci

12,070 posts

175 months

Sunday 22nd November 2020
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bagusbagus said:
From purely physics, when does riding a bike up a hill starts getting ''pointless'' in the energy being used compared to just walking with the bike up a hill?

Ie. When do the amounts of energy burned becomes same , also is there a situation/ a hill steep enough where riding a bike up a hill can actually be Less efficient than just walking and pushing the bike up the hill?
It’s not about efficiency surely?!

bagusbagus

Original Poster:

470 posts

94 months

Sunday 22nd November 2020
quotequote all
LordHaveMurci said:
It’s not about efficiency surely?!
What do you mean?
Riding on flat is anywhere between 3-5x more efficient depending on your aero/tyres compared to walking.

Riding up a hill most energy however is spent getting the mass up the gradient.

BlueComet

6,632 posts

220 months

Sunday 22nd November 2020
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Efficency (energy in vs useful work out) would be quite hard to measure just because of the shear number of variables at play, including biological/genetics between different people.

Tony1963

5,221 posts

168 months

Sunday 22nd November 2020
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I would hazard a guess that whatever speed you could comfortably walk up the hill, that’s the crossover. It’d be interesting to see graphs for it, with speed against fatblokeness.

LordHaveMurci

12,070 posts

175 months

Sunday 22nd November 2020
quotequote all
bagusbagus said:
What do you mean?
Riding on flat is anywhere between 3-5x more efficient depending on your aero/tyres compared to walking.

Riding up a hill most energy however is spent getting the mass up the gradient.
Missed the ‘pure physics’ part, ignore me hehe

frisbee

5,115 posts

116 months

Sunday 22nd November 2020
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I've overtaken walkers while going up 25%+ gradient hills.

A reasonable walking pace is only 3 to 4 mph and that is on the flat, not going up a steep hill.

I think as long as you've got the gears, cycling is always going to be more efficient. Especially if you can stay seated.

jimmy156

3,699 posts

193 months

Sunday 22nd November 2020
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I rode up a hill that was 13.something % average, although the final part was significantly steeper than that, off road / a wet grassy muddy field.


That was pretty pointless... pushing the bike up the hill was difficult enough. Riding up was (for me) impossible. The tyres would just spin if I stood, and it was too steep to just spin it out!

ETA: Strava seems to suggest the steepest part is 26.4%

Edited by jimmy156 on Sunday 22 November 17:39

yellowjack

17,205 posts

172 months

Sunday 22nd November 2020
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There's a couple of off-road hills I know of that aren't very long, but they're pretty much "roll a dice, throw a six to get to the top" hills. More often than not traction is lost before I run out of legs, but the 'point' of having another crack isn't to get up it efficiently, but to beat the damned hill into submission. Or spin the rear wheel out trying... wink

gazza285

10,098 posts

214 months

Sunday 22nd November 2020
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This steep.


keith2.2

1,100 posts

201 months

Monday 23rd November 2020
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It depends on the gearing and total system mass, I'd have thought

That and one's pride...

Edited by keith2.2 on Monday 23 November 05:38

boyse7en

7,039 posts

171 months

Monday 23rd November 2020
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I think it is always quicker and therefore more efficient to ride than walk. The crossover point is whether you have the traction available to ride it

chris7676

2,685 posts

226 months

Monday 23rd November 2020
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From a purely physics point of view both walking with bike and riding up a steep hill will require roughly the same energy/power at the same speed.
From practical point of view most bikes won't let you ride that slow / relaxed as you would walk, hence the latter is easier for most mortals.

PomBstard

7,046 posts

248 months

Monday 23rd November 2020
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This is the profile of the first 30km of an mtb race I’ve done a few times. It’s mostly firetrail and a bit of singletrack but there’s a prize for the first rider up the first fridge door to the top without getting off the bike. The rest of us walk...



Profile of the next 60km is much the same...

Howaboutthis

162 posts

68 months

Monday 23rd November 2020
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Crossover to Shank's Mare just before your chain snaps?

Daveyraveygravey

2,054 posts

190 months

Monday 23rd November 2020
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When Hardknott beat me into submitting and walking with the bike, I remember thinking the bike was making the walking harder than normal! Although cleats + Steep Tarmac complicates things further.

LimJim

2,274 posts

48 months

Monday 23rd November 2020
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Interesting question. No idea, would be curious to know.

My guess is if you have sufficient gearing and posture to maintain a reasonable cadence, I'd be surprised if there is any gradient where it becomes better to walk... During my tours of the alps on granny cog I sometimes walk but suspect this more about variety.