How long does it take to climb Alpe d'Huez?
Depends on your watts per kilogram — almost nothing else. On a climb, gravity takes over 80% of your power budget, so time up scales nearly linearly with W/kg. Here's the famous-climbs table, computed by the calculator above for a 165 lb rider on a 19 lb bike:
| Climb | Length · grade | 3 W/kg | 4 W/kg | 5 W/kg |
|---|---|---|---|---|
| Old La Honda (CA) | 5.4 km · 7.3% | 26:51 | 20:36 | 16:56 |
| Box Hill (UK / Zwift) | 2.5 km · 5% | 9:13 | 7:16 | 6:07 |
| Alpe d'Huez | 13.8 km · 8.1% | 1:15:01 | 57:18 | 46:49 |
| Col du Tourmalet | 19 km · 7.4% | 1:35:33 | 1:13:17 | 1:00:10 |
| Mont Ventoux (Bédoin) | 21.5 km · 7.5% | 1:49:22 | 1:23:50 | 1:08:46 |
| Alto de l’Angliru | 12.4 km · 9.8% | 1:19:51 | 1:00:34 | 49:08 |
Steady power, paved road, hoods position, still air; climb figures are approximate published length/grade. Your W/kg is on the W/kg calculator — then find your row here.
The model behind this page is the validated Martin et al. (1998) power equation, and our test suite pins it against the sport's best-known benchmark: 6 W/kg up Alpe d'Huez computes to about 40 minutes — which is what the fastest Tour ascents actually take. The same equation, at your watts, is what prints your time above.
How long does a 5-mile climb at 6% take — or 1,000 feet of gain?
For the climbs that aren't famous, here is the grid at a steady 200 W (165 lb rider, 19 lb bike):
| Grade | 1 mile | 3 miles | 5 miles | 10 miles |
|---|---|---|---|---|
| 4% | 5:37 | 16:51 | 28:05 | 56:10 |
| 6% | 7:35 | 22:45 | 37:54 | 1:15:49 |
| 8% | 9:41 | 29:03 | 48:25 | 1:36:51 |
| 10% | 11:50 | 35:31 | 59:11 | 1:58:23 |
Time in m:ss (or h:mm:ss); paved road, hoods, still air. Scale roughly with your own watts: 250 W is about a fifth quicker than 200 W on the steep rows, a little less on the gentle ones.
By gain instead of length: 1,000 feet at 200 W takes 23:58 on a 6% grade and 22:32 on 10%. Steeper is faster per foot of altitude, because less of the effort is spent covering the road in between — which is exactly why VAM rewards steep climbs and why comparing VAMs across different grades misleads.
What pace should you ride a long climb at?
A 20–60-minute climb is a threshold effort wearing scenery: ride it near your FTP, not above it. The classic mistake is attacking the first kilometer at VO2max pace and donating minutes to the top half — on a steady grade, an even effort is the fastest strategy physics allows. Practical version: settle into the top of Zone 3 or low Zone 4 in the first five minutes, and only spend above threshold when the grade slackens near the top, where extra watts buy the most speed.
VAM is vertical meters climbed per hour, and it's the cleanest way to compare efforts across different climbs: 4 W/kg rides Alpe d'Huez at roughly 1,167 VAM, and the number barely changes on any other steep climb at the same W/kg. The calculator prints yours; anything over 1,000 is honest work, and 1,800+ is what mountain stages are won at.
Does two kilograms really matter on a climb?
Computed, not vibed: dropping 2 kg (bike or body) at 250 W takes 1:29 off an Alpe d'Huez ascent of 1:07:54 — about 2.2% of the climb, and the same fraction holds for most long climbs. Real, but smaller than the marketing: training the numerator (your watts) moves the needle several times further than shaving the denominator. The wheel weight calculator already runs this for any grams, on any of these climbs, at your watts.
Which matters more on a climb — watts or weight?
On a steep grade, time is close to proportional to system mass divided by watts, so a 10% change in either is worth about the same. Computed on the Alpe for the 250 W, 83.5 kg rider above: 10% more power (275 W) takes 1:02:06, saving 5:48; 10% less system mass (75.2 kg) at the original 250 W takes 1:01:46, saving 6:08. The small gap between them is the air: extra watts also have to push the faster rider through it, while lost kilograms don't. The practical difference is what each ten percent costs. Ten percent of FTP is a winter of structured work; ten percent of system mass is about 8 kg, which for most riders is either a great deal of body or a second bike's worth of money, and the W/kg page prices both routes.
Does aerodynamics matter on a climb?
In inverse proportion to the steepness. Hoods versus drops at 250 W, two climbs:
| Climb | On the hoods | In the drops | Saved |
|---|---|---|---|
| Box Hill (UK / Zwift) (5%) | 8:26 | 8:21 | 5 s (1.0%) |
| Alpe d'Huez (8.1%) | 1:07:54 | 1:07:39 | 15 s (0.4%) |
250 W, 83.5 kg system, still air; CdA 0.32 on the hoods vs 0.28 in the drops.
On a 5% climb the drops still buy a few percent, because you're moving fast enough for the air to notice. On 8% they buy under one percent of a forty-minute effort — real, but smaller than the breathing you give up to get it. The rule that falls out: sit up and breathe on the steep pitches, tuck on the false flats and gentle sections where the same position is worth many times more.
Grade, gain, or both?
This calculator takes length and average grade — the two numbers every climb profile publishes. If you only know the elevation gain, grade is gain ÷ distance: 1,100 m over 13.8 km is 8.0%. The gradient calculator does the conversion (and the reverse) in both unit systems. One caveat on average grade: a climb that mixes 12% ramps with flat recoveries rides slower than its average suggests, because the time lost on the steep parts outweighs the time gained on the easy ones. Expect real-world times a few percent over the calculator on irregular climbs.