Pogačar's 7 W/kg Alpe d'Huez ride: The maths behind the myth

Seven watts per kilogram. For 35 minutes and 27 seconds. It’s a figure that sounds cooked up in a lab, not produced by a human on the brutal slopes of Alpe d’Huez.

After Tadej Pogačar’s blistering ascent, the number ‘7’ was everywhere. It’s a simple, clean, astonishing metric – and it’s almost certainly wrong.

More accurately, it’s an estimate. As the team at GCN Tech recently broke down, any power figure not taken directly from a rider's head unit is the result of reverse-engineering, based on a pile of assumptions.

Only the rider and their team have the real power file, and they aren’t sharing. So, let's unpack the maths and the myriad variables to see if that 7 W/kg figure holds up.

The Anatomy of an Estimate

To calculate the power required to complete a climb in a specific time, you need to know the forces the rider is fighting against: gravity, aerodynamic drag, and rolling resistance.

You can plug these into an online calculator like MyWindsock, but the quality of the output depends entirely on the quality of your inputs. As the GCN presenters put it, “with all of these calculations, there are assumptions being made.”

First is system weight: the rider, their bike, and all their kit. GCN estimated a total system weight for Pogačar of between 70 and 72 kg, but even this is a guess.

What did he weigh that morning? How much fluid did he lose through sweat? A kilogram here or there makes a huge difference when calculating watts per kilo.

Next is rolling resistance, the energy lost as tyres deform against the road. This depends on the tyre model, pressure, and the road surface itself.

Pogačar was reportedly on Continental GP 5000 TT tyres, and GCN used an estimated rolling resistance coefficient (Crr) of 0.005. Plausible, but still an assumption.

Then there are drivetrain losses. The power a rider produces at the pedals isn’t the same as the power delivered to the rear wheel, with some lost to friction.

GCN estimated this loss at around 2%, a reasonable starting point for a clean, pro-level drivetrain, but it’s another variable.

The Biggest Guess: Aerodynamic Drag

The real wild card is aerodynamic drag, expressed as CdA (coefficient of drag multiplied by frontal area). On a steep climb, gravity is the main enemy, but aero drag still matters.

Pogačar’s CdA was estimated to be between 0.29 and 0.31. This is the single biggest assumption in the whole equation.

With those variables in mind, let’s run the numbers on his 35-minute, 27-second climb time. In a ‘worst-case’ scenario requiring the highest power output, GCN assumed a heavier 72 kg system weight and a higher CdA, resulting in a calculated average power of 450 watts.

For a rider of Pogačar's likely weight, that is indeed “just over 7 watts per kilo.” This is where the headline figure comes from.

However, in a ‘best-case’ scenario – a lighter 69 kg system weight and a more aerodynamic profile – the required power drops significantly. The calculated figure falls to 6.8 W/kg, and another run put it at 6.7 W/kg.

That's still a world-class, monumental effort, but it’s not the magic number seven.

The Unquantifiables

It gets even murkier, because Alpe d’Huez isn’t a sterile lab environment. The presenters highlighted factors that are almost impossible to model, like the dense crowds parting at the last second to create a “tunnel of fans.”

Does that wall of people provide an aerodynamic shelter? Almost certainly, but by how much? The same goes for the flotilla of motorbikes; GCN’s own testing suggested drafting another rider on the climb could save around 10 watts.

Then there’s the measurement device itself. Pogačar’s bike is equipped with a Shimano Dura-Ace power meter, and as GCN points out, these units are “not renowned for being the most accurate, especially on the small chainring,” which he was using.

Even if we had the official data file, the number it recorded would have its own margin of error.

The Verdict: Possible, but that’s not the point

So, did Pogačar do 7 W/kg? GCN’s conclusion is that it’s “entirely possible,” an astonishing thought given the altitude (the summit is at 1,850 m), heat, and fatigue of a Grand Tour stage.

Context from a reported effort during the 2024 Tour de France, where he was estimated to have done 7 W/kg for 40 minutes after 185 km of racing, suggests he operates in this rarefied air.

But fixating on a single number misses the point. The real lesson is in the sensitivity of the calculation: a few assumptions tweaked one way gives you 7.0 W/kg, while tweaked another, it’s 6.7 W/kg.

As one of the presenters wisely quoted, “Only a Sith deals in absolutes.”

The only absolute fact is the time: 35 minutes and 27 seconds. It’s roughly 1.5 minutes faster than Marco Pantani’s legendary 1997 record, set on an aluminium Wilier.

That gap tells a story not just of a phenomenal athlete, but of decades of technological advancement in bikes, components, and apparel.

Ultimately, calculating power from the roadside is a fascinating exercise in physics. Without the data file, however, it remains just that: an exercise.

The stopwatch is the only arbiter that doesn’t rely on assumptions, and its verdict was clear. The performance was extraordinary, whatever the exact wattage.