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THE SCIENCE OF CLIMBING AT TOUR DE FRANCE SPEEDS

By Anthony Walsh
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Watch a Tour climber float up a 20-kilometre mountain pass at a speed you couldn't hold for two minutes, and it's tempting to put it in a box marked "aliens" and forget about it. They're just built different, the thinking goes, and there's nothing in there for the rest of us.

I don't buy that, and by the end of this you won't either. Because once you actually look at the numbers — what the pros produce, what you produce, and why the gap is the size it is — two things become clear. The first is a proper reality check on just how far ahead the best in the world are. The second, more useful, is that the principles governing their climbing are exactly the same as the ones governing yours. The number is theirs. The physics is shared. Let me put real figures on it.

The number that matters going up

On a climb, the thing that decides your speed isn't your raw power. It's your power-to-weight ratio — watts per kilogram — because climbing is mostly a fight against gravity, and gravity pulls on every kilo of you and your bike.

This is why W/kg is the only climbing number worth quoting. Take two riders. One produces 400 watts and weighs 80kg, so 5 W/kg. The other produces 360 watts and weighs 60kg, so 6 W/kg. On the flat, the 400-watt rider is faster — more raw power pushing through the air. But point the road uphill and the lighter rider pulls away, because they're producing more watts for every kilo they have to haul up the mountain. More raw power, slower up the climb. That's the whole reason a 60kg climber beats an 80kg engine in the high mountains.

So when we compare pros to amateurs on a climb, we compare W/kg, and the comparison is stark.

Roughly six, against your three and a half

Analysts who reverse-engineer power from climb times and gradients — because teams don't publish the raw data — consistently estimate that the best Grand Tour climbers sustain around 6.0 to 6.4 watts per kilogram for a long climb of 30 to 40 minutes. On shorter, decisive efforts the estimates go higher still. Expressed as climbing speed, that's a VAM — vertical metres gained per hour — of an estimated 1,700 to 1,850 metres an hour on the hardest climbs. These are estimates, not gospel, but they're remarkably consistent across the top climbers.

Now you. A recreational rider sits around 2.5 to 3.0 W/kg at threshold. A fit, committed amateur is around 3.0 to 3.5. A strong club racer, the kind who's near the front of the Saturday bunch, lives around 3.5 to 4.5. A genuinely elite amateur can push past 5. Which means the pro figure of roughly 6 is, give or take, double a strong amateur's, and more than double a typical fit one's.

Double doesn't sound like much until you turn it into time. Climbing speed scales closely with W/kg, so on a climb that takes a 6.2 W/kg pro around 40 minutes, a 4.0 W/kg amateur is producing roughly two-thirds of the W/kg and will take something in the region of an hour. On Alpe d'Huez, that's the pros doing it in around 40 minutes and a strong amateur taking closer to an hour, with a fit club rider somewhere past that. The gap you see on television is real, and it's exactly the size the W/kg numbers say it should be. No magic. Just arithmetic and a decade of full-time training.

The edge you can't see on the day

Here's the part the single-climb numbers hide, and it's the pros' deepest advantage: durability. Repeatability. The ability to produce that number again, and again, and again.

An amateur, on a perfect day, rested, tapered, fuelled, can produce a one-off climbing effort that's a respectable fraction of a pro's. What the amateur cannot do is produce it on the lower slopes of a climb after five hours of racing, on the third week of a Grand Tour, the day after a 200km mountain stage, and then back it up tomorrow. The pro's six watts per kilo isn't a party-piece maximum. It's a number they can hit deep into fatigue, over and over. That fatigue resistance — the ability to still climb well when you're already empty — is built by enormous volume over years, and it's the thing that separates the levels even more than the peak number does.

It's also, conveniently, the most trainable weakness most amateurs have, and the one masters riders should care about most. You may not lift your peak W/kg by much after 45. But you can dramatically improve your durability — how well that number holds up in the fifth hour — through aerobic base work and long rides. That's where your realistic gains live, and it's pure Seiler-style base training doing the work.

Improve the ratio from the right end

If W/kg is the number, you improve it one of two ways: more watts on top, or less weight on the bottom. Both move the ratio. They are not equally safe.

For amateurs, building the watts is almost always the better route. It's sustainable, it improves your riding everywhere, not just uphill, and it doesn't carry the risks that chasing a low weight does. Stripping weight by under-eating costs you power, wrecks your recovery, hammers your immune system and, for masters riders especially, does real long-term harm. The pros manage race weight with a team of nutritionists and a thin margin for error; an amateur trying to copy that without the support usually ends up lighter, weaker and ill. Improve your body composition slowly, through good fuelling and consistent training, and let the watts do the heavy lifting. The full argument is in the power-to-weight guide, but the headline is simple: build the engine before you shrink the chassis.

Track your own VAM

Here's a number you can actually own, and it's the same one the analysts use on the pros: your VAM. Vertical metres gained per hour. It's the cleanest way to benchmark your climbing against yourself across a season, and it doesn't even need a power meter — just a climb, a watch and an elevation figure.

Pick a climb you ride regularly, one that takes you somewhere between ten and thirty minutes. Note the altitude you gain from bottom to top, and time your ascent. VAM is simply the metres climbed divided by the time in hours. Climb 300 metres in 20 minutes and that's 300 divided by a third of an hour — 900 metres an hour. Do it again in eight weeks and you've got a direct, honest read on whether your climbing is improving, with all the noise of wind and traffic stripped out, because it's the same hill every time.

The fastest Tour climbers sit at an estimated 1,700 to 1,850 on the hardest climbs. A strong amateur might be at 1,000 to 1,200. You won't close that gap. But watching your own VAM climb from, say, 850 to 950 across a base block is exactly the same signal of progress, measured exactly the same way. It's the pro metric, available to anyone with a hill and a stopwatch — and it's a far more motivating number to chase than a flat FTP test, because it's the thing you actually feel on the road.

The principles scale perfectly

This is the payoff, and it's why the whole comparison matters. The number is out of reach. The way the number is produced and managed is not. Every principle that governs a pro's climb governs yours, identically.

Pacing. A pro climbs a mountain pass with an even or slightly negative effort — controlled at the bottom, strongest at the top. They don't blow themselves apart on the lower ramps. Neither should you. The single biggest time-loss for amateurs on a climb is going too hard in the first few minutes and paying for it all the way up. Same mistake, same fix, whether you're at 4 W/kg or 6.

Fuelling. A pro takes on carbohydrate constantly, long before the decisive slopes. You should too — 60 to 90 grams an hour on a long climbing day, started early. The magnitude differs; the principle is word-for-word the same.

Don't go into the red early. A pro who goes anaerobic at the base of a climb has lit a match they need at the top. So have you. Keep the effort aerobic and controlled until the moment it has to hurt.

You'll never produce six watts per kilo. That's fine — almost nobody will, and it has nothing to do with how much you can improve. What you can do is pace your climbs the way they pace theirs, fuel the way they fuel, and build the durability that lets your number hold up when you're tired. The pros are a long way ahead. But they got there by doing, at a higher level, exactly the things that will make you faster too. Watch the numbers, then go and apply the principles behind them.

Put it into practice with how to pace a long climb and, if Alpe d'Huez is on your list, the full Alpe d'Huez pacing guide. To see these numbers play out live, read how to watch the Tour like a coach. And if you want your own W/kg built properly, we're on Skool.

FAQ

FREQUENTLY ASKED QUESTIONS

How many watts per kilo do Tour de France riders produce climbing?
Analysts estimate that the best Grand Tour climbers sustain roughly 6.0 to 6.4 watts per kilogram for a long mountain climb of 30–40 minutes, with shorter decisive efforts estimated higher. These figures are calculated from climb times and gradients rather than published by teams, so they are estimates, but they are remarkably consistent across the top climbers.
What is a good watts per kilo for an amateur cyclist?
A recreational rider often sits around 2.5 to 3.0 W/kg at threshold, a fit committed amateur around 3.0 to 3.5, a strong club racer 3.5 to 4.5, and a genuinely elite amateur can exceed 5. The pro figure of roughly 6 is about double a strong amateur's, which is exactly why the time gaps on a climb are so large.
Why does power-to-weight matter more than raw power for climbing?
Because climbing is mostly a fight against gravity, and gravity acts on your total weight. Two riders producing the same watts per kilogram climb at almost the same speed regardless of their absolute power, while a heavier rider with more raw watts can still be slower uphill. That is why W/kg, not raw watts, is the number that decides a climb.
What is VAM in cycling?
VAM stands for vertical ascent in metres, the rate of altitude gain per hour. It is a way of expressing climbing speed independent of gradient. The fastest Tour climbers reach an estimated 1,700 to 1,850 metres per hour on the hardest climbs, while a strong amateur might manage 1,000 to 1,200, a gap that mirrors the difference in power-to-weight.
Can amateurs apply pro climbing principles?
Yes, directly. The principles that govern a pro's climb — pace it evenly or slightly negative, don't go anaerobic at the base, fuel constantly, and improve power-to-weight sensibly — work identically at 4 watts per kilo and 6. You can't copy the number, but you can copy exactly how the number is produced and managed.

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ANTHONY WALSH

Host of the Roadman Cycling Podcast

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