Climbing and W/Kg

Training
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As a regular Zwifter, I was under the impression W/KG was the be all end all, even when it came to flats. As I have recently learnt, W/KG means absolutely nothing unless climbing above 6% gradients. While my ftp is about 4.13 w/kg (at https://showbox.bio/ an ftp of 240 and 58kg), I get dropped very easily on the flats and also lose races descending due to my light weight.

Has anyone else fallen into the same trap? I am wondering if it is even worth being light as a cyclist, unless you live/race in the alps.

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Well, if 58kg is a natural weight and you aren’t depriving yourself, it doesn’t hurt. I don’t think you’d fare any better in the flats with a higher body weight if your power stays the same. My opinion is you’re not getting dropped on flats due to your light weight (descents might be different), you’re getting dropped due to your sustainable power output.

That said, if you feel deprived to get to and maintain 58kgs you could be negatively impacting power output. If a higher body weight helps you put out more raw power then that would be beneficial and might offset increased weight for climbing. But gaining weight doesn’t necessarily mean more power.

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So absolute watts matter a lot on flats. Look at the classics racers, they are all monsters. 75kg is on the light side for a classics specialist

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They way to think about this is not that both the larger and smaller can hold the same watt/kg, but when does the lighter rider’s higher watt/kg, but lower absolute wattage, over take the heavier rider’s absolute wattage advantage?

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Few things missing.

System weight, as a percentage, is a significantly larger tax on lighter riders.
Rolling resistance is a greater percentage of loss for lighter riders.
Mechanical loss is also a greater percentage of loss for lighter riders.

There’s been quite a few studies on this. A few magazines and YouTube channels have attempted to compare the two. Usually, the results surprise the testers.

At equal w/kg. Two riders, one 60kg, one 80kg. The 80kg rider will have an advantage on all terrain. Everything. Remember, equal strength riders, by w/kg.

Flat, larger riders have more muscle mass, it’s not a penalty, even in regards to CDA. I’ve read many attempts to quantify it. It’s incredibly variable due to a million reasons. However, hypothetically two identical riders, scaled perfectly up. The larger rider usually has a .25-.50 w/kg advantage on a flat road. Muscle mass vs CDA. It’s an equation, something to do with cubic volume vs frontal area. I’ll attempt to find it. It’s real.

Cannondale did the climbing, gravity vs aero science in their Super Six white paper. The crossover to advantage gravity vs aero is related to ultimate power. For a 3w/kg rider, it’s a low gradient. Something like 5%. For a World Tour athlete, say 6w/kg, the crossover is far higher 8/9/10%. They are travelling so much faster that aero remains a large factor right up to high gradients.

Take a real world example.

60kg 4w/kg rider
80kg 3.7w/kg rider

The lighter rider is slower nearly everywhere, flat, downhill, false flat…

In order for the lighter rider to be faster the gradient would need to be nearly all of the power requirements. So likely 8% or above. The lighter rider has to overcome the bike and system weight being a greater percentage of their power, rolling resistance and mechanical drivetrain loss. At .3w/kg it would be very close to a wash.

Now, a poster above made a fantastic point. One many overlook.

Fueling.

The longer the event, the greater the advantage for the smaller rider. On the proviso, it’s a road race and they are able to draft on flats and downhills etc.

Imagine 2 riders, hypothetical situation, same fat oxidation ratios, same aero shape, same humans, one is just proportionally scaled up to 20kgs heavier.

Both riders hitting the magical 100g/h fueling.

6 hours into the race and the 60kg rider has taken in 600g of carbs. 2400 cal. They’ve used say 3600 cal to get to the final climb. They have 800 cal of glycogen left for the final climb effort.

80kg rider has used say 4800 cal to get to the final climb. Same 100g/h fueling. They have 200 cal of gylocogen left for the final climb.

They are in a greater deficit.

Now, the larger rider can intake more cal, they can store more glycogen, however it is not anywhere near as high as it should be, relative to the smaller rider. Whomever built us got the math wrong :grin:

Compound this with the fact that many heavier riders don’t exceed 100g/h. If they were able to tolerate and absorb, say 130g/h it would be awfully close.

Takeaway. Larger riders need be certain they are at max fueling ratio in races. Particularly, in longer events.

In regards to climbing. I’d say for most competitive amateurs the crossover is the 8% realm. That’s just a seat of the pants measurement for 4 to 5w/kg riders. That’s were aero becomes negligible. Gravity becomes the vastly greater percentage.

Personally, as a light rider 60-62kgs. I would never attack etc on anything less than 10%, if I was in control of the racing situation. Even then, the race would have to finish on the climb. As if it didn’t, I’d likely be caught on the downhill or run in to the finish.

The way many people ride, particularly group rides where hills are raced gives many the feeling that w/kg is everything. Obviously, it’s very important.

I don’t think there’s an exact grade where absolute power trumps w/kg. As the gradient angle varies in a ratio to speed of the rider.

I’d be comfortable with 8%, as a estimate for most recreational riders. Anything less, aero is a significant factor, so raw power is still an advantage. If there’s drafting in the equation, I’d say 10%.

9 Likes
26

Great answer. This confirms my priors as well, which makes it even better (lol jk).

The fueling element makes sense too.

I always found cycling curious because in T&F, the skinny people always gravitate towards endurance events and dominate, whereas in cycling you get more well build people being competitive outside of a pure sprint finish.

I remember seeing Miguel Induráin and wonder what’s going on w this guy when I compared him to the emaciated guys dominating the TdF GC (when I started following cycling in 2010 onwards). LA was a big guy too (73kg at 5’9” is relatively high weight per inch), Jan Ullrich, and now WVA (who isn’t GC but does it all), etc.

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Well first of all……EPO.

Second, those guys haven’t raced in 15+ years….and the sport has changed dramatically since then. Guys their size would get destroyed in the GC today (doping aside). Today’s elite riders are emancipated……

1 Like
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I think the main issue is the continued fixation on Grand Tour riders, in general.

Amateurs are not racing the TDF. Its demands are wildly different to what most of us compete at. I’d go as far as saying, it’s almost a different sport. How they train, how they fuel, their body composition targets, all have little to no bearing on how we should tackle the sport.

Where I live (New Zealand) we do not have a single race even remotely like the TDF. Not one. Yet, local riders are endlessly discussing how the riders train, fuel etc.

It’s only relative to your location and target events. If you regularly race events with climbs longer than say… 20mins, then yes, you’ll probably need to look like you’ve been stuck on a deserted island.

For everybody else, that’s a lot of folk, you’ll be better served by simply being more powerful. Carrying a little more lean muscle mass in your upper body and legs. A powerful well rounded athlete.

You’ll sprint better, recover faster, be more durable, more resistant to injury and illness. Generally, you’ll be a healthier human. Fuel properly, get powerful.

Riders like MVDP and Wout are great examples. Strong athletic weapons. Able to win on very varied terrain.

From my own experience, I was 59kgs and lean, but weak as a wet bus ticket from the constant calorie restriction.

I changed trajectories recently, I turbo charged my fueling at 100g/h in key sessions and started doing strength work again. Result. I’d smash my skinny 59kg self. It really wouldn’t even be a race.

Sprint is back up to 1200w at 62kg.

I climb about the same, but I’m stronger everywhere else. In particular, the end of a race, where it matters. That’s because as a stronger, better fueled athlete I’m able to travel through the race using a smaller percentage of energy.

Summary.

Power wins races.

W/kg also wins races, just not the races most of us compete in.

(Obviously, if you live in Andorra or only race the British Hill Climb series, ignore everything I just said… enjoy your kale salad) :grinning:

2 Likes
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Holy!

A GCN video that’s actually spot on and not an ad. Miracles.

Allometric scaling, that’s the term I was hunting for.

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You mean emaciated. Skinny af. Not liberated from political restrictions.

2 Likes
32

Autocorrect….I understand the difference between the two terms.

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All rider types took epo so that’s cancels out. From what I understand, they TT used to be much longer and that gave an advantage to better built powerful riders

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So previous posters have demonstrated that mathematically, the larger rider with higher absolute watts and same w/kg is preferable despite the gradient.

So in practice, the question then becomes why do we have these emaciated riders (with big body frames). Why?

Is it that it is much easier to drop body weight and even while losing some absolute power to push up w/kg as opposed to increasing absolute power holding kg fixed (or increasing power at a faster rate than kg)?

Is it instead that in practice, the huge w/kg ftp tend to occur in smaller riders (true climber body types: <=65kg). If so, why is that the case?

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Yeah, I’m not going down the whole “everyone was doing it” rabbit hole…

Your theory re: the length of TT’s doesn’t hold up, though…Indurain was always at the front of mountain stages. While he never won a mountain stage during his reign, that was largely because he let others take the stage wins.

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The limiting factor is VO2 max. See this Hunter Allen blog post on calculating VO2Max from FTP. At the same power to weight ratio, a larger rider needs a higher VO2 max, which is why on balance, the best climbers tend to be lighter riders.

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Forget that everyone was doing it or not. Armstrong raced Pantani and they both were doing it. He could climb with or out climb Pantani depending on the day. Armstrong is not a climber rider type whereas Pantani is a classic climber build. This post is about the physics behind how that’s possible if we are to believe it’s all about w/kg.

What is you take to explain how MP and LA climb at the same level as GC competitors given their drastically different body weight?

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I’m not sure that explains it given that vo2max is itself a metric relative to weight (ml of oxygen consumption / kg of body weight).

If you look at that equation in the article, if you hold w/kg ratio constant, the vo2 will always be identical between the big and small rider

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MP being MVdP? Can you point me to where he is climbing at the same pace as GC guys?

ETA - sorry, you meant Pantani. There are many factors that go into it…but foremost is the assumption that they are putting out equal efforts because they are riding together. That is not necessarily true. Same pace does not equate to equal efforts.

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Apologies if this is a bit off topic. Reading through made me think about one of my mental digs into the minutiae…

I know this is too vague to get a clear answer, but how much difference does weight make with regards to accelerations out of corners, as opposed to steady long climbs (of which there are none nearby)? How would 100g stack up vs 1w CRR (e.g. changing 2xVittoria latex tubes to Revoloop 25g).

Most races near me are mostly flat and seem to have 4 corners and are 5-8 laps. AC is a weakness and everyone seems to love to sprint out of every corner then just pootle along until the next corner, but I obviously don’t want to fall off the back of the group or lose a decent position by not also pushing out of the turns.