On a couple of podcasts Nate has mentioned an the idea about rider size that seems wrong to me.
He seems to think that…
For the same w/kg larger riders generally have an advantage over smaller riders (true)
Beyond a certain steepness this is no longer true and smaller riders have an advantage with the same w/kg
I think 2.'s not right.
Larger riders typically have an advantage at the same w/kg because they typically have better w/cda and always - assuming equal bike - better w/rolling resistance and w/kg(bike).
Afik, none of these advantages reverse at steep gradients. Drag and RR reduce to become negligible, but w/kgbike remains. So even on steep gradients, the bigger rider goes faster for the same w/kg.
My guess is that Nate is confused with larger riders typically being faster at grades up to around 5 or 6% (for pros anyway) and the ‘pure climbers’ having an advantage on steeper grades. But this a higher watts cda versus higher watts/kg thing…
I think riders with a lower weight might have slightly better acceleration on steep inclines for the same w/kg due to less inertia? But I agree, 4w/kg is 4w/kg on a long climb whether that’s 200 watts at 50 kilos or 300 watts at 75 kilos.
I think there’s a perception in pro cycling that smaller riders are better at quick punchy attacks and irregular climbs, whereas bigger riders are better at riding the climbs at a steadier pace (Dumoulin for example). I’m not sure how well supported that actually is in reality, as some big riders are plenty punchy and some light riders are diesels (Quintana was always better at long climbs).
Always like this graph to show how a 75kg rider riding at 300 watts is affected at different inclines by different forces, would be great to see one with different weights but same w/kg and see if/where the speed curves are…
There is the issue of heat dissipation which favors smaller riders (both shorter and lighter) and the effect is amplified at lower speeds (like when climbing).
Plus a 90kg rider at 4w/kg is burning a lot more calories than a 65kg rider at the same w/kg which is also generating more heat.
Everyone knows that the people different than oneself are the one’s with the biggest advantage
In a physics sense, larger riders are doing more work. They’re moving not just more mass but also a physically larger object through space and time.
Smaller riders have to try less hard to get aero, can draft on the flats, need less watts up the hills, need to carry and consume less fuel and can accelerate at the same rate with less raw watts.
They also have less rolling resistance.
Larger riders… Nope, can’t think of many advantages.
We get to dive bomb hills I suppose but this is anti-social in a group setting and often pushes you faster than other limiters such as the terrain and road furniture so you end up wasting all your accrued potential energy in the form of heat and worn out brake pads.
The best weight to be is the centre of the bell curve for your local cycling scene or your chosen discipline. Being at either extreme makes riding or racing in company frustrating.
I scribbled this a while ago. It ignores rolling resistance, but otherwise captures the gross forces on a rider. It basically states that at both steady state and accelerating, for a constant CdA and air conditions, at a constant power to weight, velocity scales with the cube root (steady state) or square root (accelerating) of mass, with the two speeds converging as the velocity tends to zero.
So in isolation, all else being equal, a lighter ride should never have an advantage at the same power to weight.
What it does also show however is the effect of changing CdA, and one of the best ways for a rider to do this is to put a team mate in front of them!
#2 is wrong. See this thread where I asked the same question: Climbing and W/Kg
By Physics, the bigger rider will always be faster at the same w/kg on a climb, holding all other factors constant. In practice, since the larger rider produces more watts and requires more fueling to do so, the smaller rider might have an advantage if the climb is long enough, but this is due to nutrition constraints (or however you want to word it)
What evidence is there that watts and weight are correlated anyhow?
Cycling needs very little raw strength. It’s muscular endurance. Arguably standing up from your desk takes more raw power.
Tiny tiny pros can push 400w for an hour.
If I was 85kg or 115kg I’d have a 180w ftp off the sofa.
And if I train I have a 330w+/- ftp at either weight too and likely that wouldn’t change way down into the 70’s.
My body fat percentage decides my w/kg- my muscle mass stays remarkably consistent.
Being heavier makes me slower- I don’t need any more muscle than I have to push a crank round and round
This is a great chart. As in most things, the answer to the question around what gradient does w/kg start to matter more is ‘it depends’.
I immediately thought of a triangle with two legs, CdA and w/kg that contribute to overall speed. As the grade changes, the contributions of each to overall speed reduction will change. The details will be different for every combination of rider (height, weight, natural riding position, helmet, clothing) and bike (bearings, tire choice, frame, wheels, etc).
I dont know if there is an available dataset, but intuitively, for pros who are highly trained and therefore dont have excess body weight (fat), watts are correlated with weight. The larger riders have more muscle mass since they all have similar body fat percentages. So you would expect to see ‘ftp’ or whatever metric you want (5min power, etc) correlated with riders body weight.
For example, Evenepoel probably has an almost 400w ftp, whereas WVA prob has a 440w ftp (10% higher).
For non-elite/pros, there would be a much weaker correlation (but id argue still positive) since they arent highly trained and probably have much higher body fat percentages- relatively speaking.
Your muscle mass is correlated with your body ‘frame’, and that is constant regardless of body fat%. Watts are definetly correlated with body ‘frame’ (bigger frame → bigger watts).
Nope, can’t think of many advantages.
