Twenty-one hairpins. 13.8 kilometres. 1,071 metres of climbing at an average of 8.1%. Alpe d'Huez is the most famous climb in cycling, and every rider who has ever watched the Tour has done the same maths in their head: could I get up that thing, and how fast?
The short answer is simpler than most people expect. On a climb this steep and this long, your time is decided by one number — your watts per kilo. Not your handling, not your gearing, not how aero you are. Just how much power you can hold for around an hour, divided by how much you weigh. Get that number right and the finish time is almost pre-written.
So let me give you the real targets, what they mean, and how to build toward the one you actually want.
Why W/kg is the only number that matters here
On flat ground, most of your power fights air resistance. That's why heavy, powerful riders can be brutally fast on the flat — they make big watts and the extra weight barely costs them.
Point the road uphill at 8% and everything flips. On a gradient that steep, roughly 85-90% of your power goes into one job: lifting your body and your bike against gravity. Air resistance almost stops mattering because you're moving slowly. What's left is a near-pure test of power-to-weight.
That's why a 60kg climber putting out 240 watts (4.0 W/kg) will drop an 85kg rider making 320 watts (3.8 W/kg) on the Alpe, even though the bigger rider produces 80 more watts. On the flat, it wouldn't be close the other way. Uphill, the featherweight wins. If you want the full mechanism, we broke it down in the power-to-weight ratio guide — but the short version is: on Alpe d'Huez, W/kg is king.
The power targets, by finish time
Here's a working model I use with riders targeting an Alpe ascent. It assumes even pacing, a rider-plus-bike system weight, and a sustained effort — essentially your one-hour power.
A useful rule of thumb: finish time in minutes ≈ 240 ÷ your sustainable W/kg. It's an approximation, but it's close enough to plan around.
- 6.2 W/kg → sub-40 minutes. Pro and near-pro territory. This is what wins Tour stages. For 99% of amateurs, this is a number to admire, not chase.
- 5.0 W/kg → around 48 minutes. Strong regional racer, Cat 1-2 level. A serious, dedicated result.
- 4.5 W/kg → around 53 minutes. Committed amateur racer who trains with structure year-round.
- 4.0 W/kg → around 60 minutes. The classic "good amateur" benchmark. Breaking the hour on the Alpe is a genuine achievement and a target worth building a season around.
- 3.5 W/kg → around 68 minutes. A fit, regular sportive rider. Very respectable, especially on a first attempt.
- 3.0 W/kg → around 80 minutes. A solid recreational cyclist getting up a legendary climb under their own steam. Nothing to apologise for.
- 2.5 W/kg → around 96 minutes. First-time climber or someone coming back to fitness. You'll make it, and you'll remember it.
To translate that into watts, multiply the W/kg by your total climbing weight. A 70kg rider chasing the hour needs about 280 watts (4.0 × 70). An 80kg rider chasing the same time needs about 320 watts. Same time, very different wattage — because W/kg, not raw power, is what the mountain reads.
System weight, not bodyweight
Here's the detail that trips people up. The "kg" in your W/kg on climb day isn't your bathroom-scale weight. It's everything that goes up the hill: you, the bike, two full bottles, food, tools, spare tube, the lot.
That's often 9-11kg of bike and kit on top of your bodyweight. So a 70kg rider is really moving 80-81kg up the Alpe. If you want your climbing W/kg to reflect reality, use system weight.
The practical upside: system weight is partly under your control on the day. Dropping 2kg — whether from a lighter bike, one bottle instead of two on a sub-hour climb where you don't need the fluid, or genuine body-composition work over a training block — lifts a 75kg rider's effective W/kg by around 0.15. On the full climb, that's the better part of a minute. It's not marginal.
That doesn't mean starve yourself. Cutting weight the wrong way costs you power, and power is the bigger lever. But it does mean that if you're serious about a time, both sides of the ratio are in play. We covered how to lose weight without wrecking your numbers in fuel for the work required.
The pacing mistake that ruins most first ascents
The single biggest reason amateurs miss their target on Alpe d'Huez has nothing to do with fitness. It's pacing.
The climb is at its steepest — up to 10-12% — in the opening kilometres, right through the first few hairpins out of Bourg d'Oisans. That's precisely where adrenaline is highest and riders feel fresh. So they attack the bottom, spike well above their sustainable power, and pay a compounding tax for the next 50 minutes.
Power over your threshold isn't a loan. It's a loan with brutal interest. Every minute spent 20 watts too high early costs you far more than 20 watts of slowing later.
Do the opposite. For the first three hairpins, deliberately ride 5-10% under your target average power. Let riders come past you. Settle into a cadence and a breathing rhythm you could just about hold a fractured conversation at. Then, from roughly the halfway point, if the legs are there, you edge the power up. In the final 3km, once the gradient eases slightly and the top is in sight, you empty the tank.
Ridden that way, an even or slightly negative split, the Alpe gives you your best possible time for the fitness you brought. Ridden hero-at-the-bottom, it embarrasses you. The same logic applies to any long climb — there's more on it in pacing strategy for long climbs.
How to train for the number you want
If your current sustained W/kg is 3.2 and you want 4.0 for the Alpe, that's a real gap — roughly a 20-25% improvement in power-to-weight. Depending on your starting point that's a season of focused work, not a six-week fix. Here's where the gains come from, in order of return.
Threshold power. The Alpe is an hour-long effort, so your one-hour power — your true FTP — is the engine. Build it with sustained work: 2×20-minute or 3×15-minute intervals at threshold, and longer sweet-spot blocks (88-94% of FTP) as the season progresses. Two quality sessions a week, no more, with easy riding around them.
Aerobic base. You can't hold threshold for an hour if your aerobic engine can't support it. The bulk of your riding — 80% of it — should be really easy, endurance-paced. This is the unglamorous work that lets the hard sessions actually stick.
Repeatability at threshold. The difference between a rider who holds 4.0 W/kg for the full hour and one who fades to 3.6 in the last 4km is durability. Long rides with threshold efforts placed late — when you're already tired — build the ability to hold power deep into a climb.
Body composition, carefully. If there's weight to lose without sacrificing power, it's the other half of the ratio. Do it slowly, fuel your hard sessions properly, and never diet through your key training blocks.
Actual climbing, or a good simulation. If you have hills, ride them. If you don't, long threshold intervals on the trainer at a high resistance and low-ish cadence mimic the specific demand well.
Be honest about the number
There's a version of this where I tell you anyone can do 6 W/kg with the right plan. That's not true, and you'd see through it anyway. Genetics, age, training history and time available all set a ceiling on your sustainable power-to-weight.
But here's what is true: almost every amateur I've worked with is riding well below their own ceiling, not because of biology but because their training lacks structure. Random hard rides plateau fast. A proper build — base, threshold, specificity, recovery — is what turns 3.2 into 3.8 into 4.0.
That's the whole reason the Not Done Yet community exists. Members get a structured plan built around their target event, the same periodisation the pros use, and a coach who'll tell them honestly what's achievable and how to get there. It's $195 a month, and if a climb like the Alpe is on your list, that's the fastest way to arrive at the bottom ready. You can find it at skool.com/roadmancycling.
Pick your number. Train for it properly. And when you're stood at the bottom of those 21 hairpins, you'll already know what you're capable of — because you'll have done the maths, and you'll have done the work.