why do lighter cyclists climb faster?

pep.fermi

For similar "general cycling fitness", lighter cyclists tend to climb faster.
Why?

Nothing nothing as I do, I would expect that 1) what counts is more power/mass, rather than power, and 2) less mass also means smaller muscles, so far from obvious to me that lighter cyclist have better power/mass ratio

rick_chasey

Trigonometry.

pep.fermi

rick_chasey said:

Trigonometry.

Interesting and unexpected answer.
Can you please elaborate?

pep.fermi

I googled it already of course, and the answer I tend to get is "what counts is power/mass, so with less mass IF YOU HAVE THE SAME POWER you get a better power/mass." But this I find it nonsense, because with less mass you don't have the same power, you get (proportionally?) less power.

daniel_b

It's simply power to weight, watts per kg.

Pidcock does not have the power of Ganna, but can climb faster than him.

Not all lighter cyclists will climb faster though, it's all down to w/kg.

ugo.santalucia

daniel_b said:

It's simply power to weight, watts per kg.

Pidcock does not have the power of Ganna, but can climb faster than him.

Not all lighter cyclists will climb faster though, it's all down to w/kg.

power to mass over a given timeframe. In our game there are riders who can do 12-13 W/kg for one minute, but cannot do 6 W/kg over 5 minutes… equally, there are some who can do 7W/kg for 5 minutes or more, but cannot do more than 9 or 10 over one minute…
Anecdotally, the latter tend to be lighter than the former, who are also referred to as power trolls.
Most Uk climbs are under 6 minutes long, so climbing speed is a very relative concept

wallace_and_gromit

Assuming we're talking about "long" i.e. primarily aerobic climbs, then it's because sustainable power increases in proportion to the square of (1+i) where i is the proportionate increase in height whereas mass increases in proportion to the cube of (1+i).

Power depends on the square, as aerobic power, all other things equal, depends on the cross sectional area of the heart (i.e. a quantity in 2 dimensions) whereas mass depends on 3 dimensions (height, width and front-to-back).

So riders gain more mass relatively than aerobic power by being bigger, all other things equal and so taller (and hence heavier) riders have a lower watts/kg.

For rowing and swimming, resistance increases in the same proportion as aerobic power as height (and hence mass) increase, so for these sports, being taller and heavier is better, as being taller allows for a more efficient stroke. Hence the proliferation of 6'6" male rowers and 6' female swimmers.

sungod

actual pedal force required for climbing isn't that high vs. maximum pedal force achievable by a rider

a lighter rider's muscles can still exert far more force than they actually need for climbing

i.e. raw power isn't the constraint, unlike, say, sprinting

sustaining enough power for long climbs is a matter of oxygen uptake, metabolic efficiency etc., where size doesn't make much difference

a lighter rider still has more than enough muscle to generate the necessary power, if they have similar vo2 max etc. vs. a heavier rider, they will have superior power:mass and climb faster

pep.fermi

wallace_and_gromit said:

sustainable power increases in proportion to the square of (1+i) where i is the proportionate increase in height

Where does this come from?

pangolin

pep.fermi said:

I googled it already of course, and the answer I tend to get is "what counts is power/mass, so with less mass IF YOU HAVE THE SAME POWER you get a better power/mass." But this I find it nonsense, because with less mass you don't have the same power, you get (proportionally?) less power.

You'd be right if mass always scaled proportionately with power but I don't think that's often the case.

For one thing only a few muscles matter for cycling up a hill but the mass will tend to be spread out everywhere. Some will be fat not muscle. Some will be bones, fluids, blah blah blah. Even the extra mass that is muscle in a relevant muscle group might not be particularly efficient at delivering power for a sustained threshold effort.

pep.fermi

I'd love to see a chart, collected from a group of cyclists with similar "general cycling fitness", and say similar height too, with one axis plotting Watt/Kg, and the other Watt. Sure someone must have collected and presented this...

ugo.santalucia

sungod said:

actual pedal force required for climbing isn't that high vs. maximum pedal force achievable by a rider

a lighter rider's muscles can still exert far more force than they actually need for climbing

i.e. raw power isn't the constraint, unlike, say, sprinting

sustaining enough power for long climbs is a matter of oxygen uptake, metabolic efficiency etc., where size doesn't make much difference

a lighter rider still has more than enough muscle to generate the necessary power, if they have similar vo2 max etc. vs. a heavier rider, they will have superior power:mass and climb faster

Well, define climbing… famously Callum Brown won an Open hill climb race averaging in excess of one thousand watts… admittedly rhe climb was one minute long… but a ton is a ton… most bikes would fold if you exert in excess of a ton from a standing start.
I think the problem here is tht people think of the Tourmalet, rather than the more common Tom’s hill

focuszing723

This chart proves the fact lighter things (W/KG) have the advantage over larger things when ascending stuff. When you think about rockets having to break the Earths gravity you need loads of thrust to compensate for heaviness. It makes you wonder if on other planets heavier things can get around this by anti gravity greatness.

Hmmm, interesting.

mudsucker

Depends if the weight you have is muscle (i.e power) or fat (mass that slows you down).

pangolin

pep.fermi said:

I'd love to see a chart, collected from a group of cyclists with similar "general cycling fitness", and say similar height too, with one axis plotting Watt/Kg, and the other Watt. Sure someone must have collected and presented this...

Why?

pep.fermi

mudsucker said:

Depends of the weight you have is muscle (i.e power) or fat (mass that slows you down).

Thanks.
Heavier pro climb slower than lighter pro. I doubt they have more fat.

pep.fermi

pangolin said:

pep.fermi said:

I'd love to see a chart, collected from a group of cyclists with similar "general cycling fitness", and say similar height too, with one axis plotting Watt/Kg, and the other Watt. Sure someone must have collected and presented this...

Why?

I'd love to see it because I'm curious.
I bet some has collected it, because we people like collecting data and trying to draw conclusions from them.

ugo.santalucia

pep.fermi said:

mudsucker said:

Depends of the weight you have is muscle (i.e power) or fat (mass that slows you down).

Thanks.
Heavier pro climb slower than lighter pro. I doubt they have more fat.

on a climb like Mur de Bretagne someone like Van Der Poel might edge the TdF climbers. There is more than just Alps and Pyrenees

de_sisti

There is a woman in our club, 5ft 2ins, weighs about 7.5 st (max) and has been cycling for years. She is in her 50s and began cycling in her early teens. Despite having lots of endurance from all of her audaxing years, she struggles with climbing. One factor to consider is the importance of muscle mass and strength in climbing. Individuals with more muscle mass might face challenges on steep climbs, even if they are lighter overall.

Two other women in the cycle club share similar age, height, and weight but come from a running background. One of these women used to get a London Marathon place without having to do sponsorship/fund-raising. Her best time was <3hrs, and she took to cycling like a duck to water. Her success in climbing could be attributed to her prior running experience and the unique muscle development it provided. It's a testament to how different athletic backgrounds can impact cycling performance.

The third woman is a very good half-marathon runner, regularly completing them in around 1 hr 30 mins to 1 hr 40 mins. While she enjoys cycling, she struggles with climbing. This discrepancy could be influenced by factors such as body composition and metabolism. Individuals with similar weights might have different body compositions, affecting their cycling performance.

In my opinion, training methods and cycling techniques also play a crucial role. Some cyclists may excel in climbing due to specific training regimens or refined climbing techniques that others might not have adopted. Additionally, mental toughness and strategic approaches to climbing can contribute significantly to performance, going beyond physical characteristics.

It's essential to acknowledge the impact of environmental factors as well. Wind conditions, temperature, and altitude can affect cyclists differently, contributing to the observed variations in climbing abilities within our cycling club.

I think that being lighter in weight doesn't always guarantee good climbing ability. The interplay of muscle mass, training methods, body composition, mental toughness, and environmental factors creates a complex web of variables that influence a cyclist's performance on hills

MidlandsGrimpeur2

Much of the above with regards power, w/kg, mass over time frame, aerobic capacity etc. is all correct. As someone who is 57kg, the simple fact is, dragging a much lighter body up a climb is far easier than dragging a heavier one, that is in large part w/kg, but I have a feeling that a lighter rider with lower power will still be quicker than a heavier rider with better w/kg. Only one example but I have a mate who has a slightly higher w/kg but is 25kg heavier than me. On short UK stuff we are on a par, on alpine climbs I am significantly faster than him.

pblakeney

MidlandsGrimpeur2 said:

Much of the above with regards power, w/kg, mass over time frame, aerobic capacity etc. is all correct. As someone who is 57kg, the simple fact is, dragging a much lighter body up a climb is far easier than dragging a heavier one, that is in large part w/kg, but I have a feeling that a lighter rider with lower power will still be quicker than a heavier rider with better w/kg. Only one example but I have a mate who has a slightly higher w/kg but is 25kg heavier than me. On short UK stuff we are on a par, on alpine climbs I am significantly faster than him.

That's because it is hard for the heavier rider to maintain the high w/kg for hours on end while it is relatively easy for a short burst. Speaking from experience. 😉

MidlandsGrimpeur2

I couldn't possibly comment PB 😂

DeVlaeminck

MidlandsGrimpeur2 said:

Much of the above with regards power, w/kg, mass over time frame, aerobic capacity etc. is all correct. As someone who is 57kg, the simple fact is, dragging a much lighter body up a climb is far easier than dragging a heavier one, that is in large part w/kg, but I have a feeling that a lighter rider with lower power will still be quicker than a heavier rider with better w/kg. Only one example but I have a mate who has a slightly higher w/kg but is 25kg heavier than me. On short UK stuff we are on a par, on alpine climbs I am significantly faster than him.

It's probably down to being better at different durations - if he has a better w/kg over an hour then he should be beating you up an hour long climb unless there is something to do with the gradient engaging different muscles or him not handling altitude or something.

I'm 80kg (well Im more but when I was bike fit I was) so not that heavy but for an amateur cyclist probably above average, but I climbed longer stuff better than the short power climbs.

rick_chasey

pep.fermi said:

rick_chasey said:

Trigonometry.

Interesting and unexpected answer.
Can you please elaborate?

Though I would add about half the peloton weighs more than me and they *all* climb enormously faster than I do; near enough twice the speed.

MidlandsGrimpeur2

It's probably down to being better at different durations - if he has a better w/kg over an hour then he should be beating you up an hour long climb unless there is something to do with the gradient engaging different muscles or him not handling altitude or something.

Yeah he does, as that is based off FTP. That's why I suspect there are other factors at play over longer durations. Having said that, on long climbs and even with shorter stuff, I think other factors come into play with regards how quick you are. On local climbs I am top 10 on Strava on a lot of them, mainly up against guys who are E/1/2 riders. They are heavier and more powerful but my speed on the climbs is comparable to theirs. There must be something compensating for the lower power I have and my guess is that weight (and probably efficiency) is a significant part of it.

That is just purely logical guesswork though, I have no science to back it up!

DeVlaeminck

If your bigger friend is putting out more w/kg up hills than you then he will (ignoring unrealistic possibilities) be faster.

There must then be some reason why his higher ftp in terms of w/kg is not translating into a higher w/kg on these extended climbs.

pblakeney

DeVlaeminck said:

If your bigger friend is putting out more w/kg up hills than you then he will (ignoring unrealistic possibilities) be faster.

There must then be some reason why his higher ftp in terms of w/kg is not translating into a higher w/kg on these extended climbs.

As a heavy rider I can maintain a (relatively) high w/kg for 45-60 minutes, no more.
If I know a climb is going to take more than 60 minutes then I have to pace accordingly.

This is entirely consistent with ftp which is a calculated effort for 60 minutes.

DeVlaeminck

Define bigger. I suppose riders with a lot of fast twitch muscles may tend to be bulkier or find it harder to get really lean and that could explain it.

pblakeney

DeVlaeminck said:

Define bigger. I suppose riders with a lot of fast twitch muscles may tend to be bulkier or find it harder to get really lean and that could explain it.

In my case, excess weight that can easily (I wish) be shifted without losing power. Even when at peak performance, slimmed down, people concerned about my health, 75kgs.

pblakeney

Here is an experiment anyone with a smart trainer can try. I did and was astounded.

To feel the difference for yourself change your virtual weight up if light, down if heavy by 20kgs and ride your favourite climb. 20kgs as that took me from 85kgs to 65kgs.
I did Sa Colobra at my usual pace. Gawd it was easy with the weight loss.
I then did it at full gas. I knocked 12 minutes off my PB. I deleted these rides from Strava.