Col du Portet: Cycling Climb

The climb · France

About Col du Portet

The Col du Portet begins with a substantial climb out of Vignec beside Saint-Lary-Soulan, following the road towards Pla d’Adet before turning towards Espiaube. The valley soon falls below the road as the bends gain height. At roughly 16 kilometres, the ascent leaves little scope for mistaking its scale: the opening slopes establish a demanding effort that continues well beyond the resort junctions.

Above Espiaube, the road winds higher into open mountain country, with the upper hairpins and a short tunnel marking the approach to the col. The changing views do more to divide the climb than any long respite in the gradient. It is the sustained nature of the ascent, from the valley-side road to the high final bends, that gives Portet its weight. Reaching the crest feels like the completion of a whole mountain rather than a final isolated ramp.

01 / The ascent

Elevation profile

Start 823 m · Summit 2,207 m

Gradient by distance16.02 km / 1,389 m gain

0 km3.2 km6.5 km9.7 km13 km16.2 km

02 / The crux

Where it gets difficult

Choose a distance to find the steepest continuous section of the climb.

Steepest 500 m average

10.9%

Where to find it

2.20–2.70 km from start

Net height gained: 55 m
Section length: 500 m

The whole climb16.19 km

0 kmFinish

03 / The numbers

Climb statistics

Distance: 16.02 km
Elevation gain: 1,389 m
Average gradient: 9.0%
Climb category: HC
Start elevation: 823 m
Summit elevation: 2,207 m

Current weather

At the climb start

Loading weather…

Weather data: MET Norway

04 / Your effort

How long would it take?

Enter the power you could hold for the whole climb. We calculate a moving time from the elevation profile and the forces you ride against.

Sustained power

W/kg

Use your intended climbing effort, rather than FTP unless you can hold it for the predicted duration.

Rider weight (kg)

Bike + kit weight (kg)

Bike + kit includes clothing, bottles and luggage.

Advanced settings

Defaults represent a road-bike scenario. Adjust these settings to match your tyres, drivetrain and riding position.

Effective drag area (CdA) (m²)

Rolling resistance (Crr)

Drivetrain efficiency (%)

Modelled moving time

1 h 32 min

Power throughout: 225 W
Average speed: 10.5 km/h

Based on the 16.19 km elevation profile. Assumes steady power, with no stops, braking or drafting. Rounded to the nearest minute.

The science behind the calculation

For each part of the stored profile, we solve the steady-state cycling power equation for speed, then add distance ÷ speed across the climb. Gravity uses rider + equipment weight; available power is W/kg × rider weight. This uses the profile’s distance and elevation together, without mixing in another route’s metrics.

Power × efficiency = gravity + rolling resistance + air resistance + bearing losses

The resistance equations are adapted from Martin et al. (1998), Validation of a Mathematical Model for Road Cycling Power. Air density changes with profile altitude using NASA’s standard-atmosphere model. This calculator’s adaptation has not been independently validated.

It predicts travel at the power you enter, including on descents. It does not model acceleration, cornering, braking, traffic, wind, changing weather or fatigue. At altitude, choose power you can sustain there: thinner air reduces drag, but this model does not predict its effect on your ability to produce power. Profile quality and assumed equipment settings also affect the result.

05 / On the ground