Col de la Croix: Cycling Climb

The climb · France

About Col de la Croix

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Daniel Friebe’s Mountain High

From Saint-Jean-de-Maurienne, the eastern ascent of the Col de la Croix de Fer unfolds in distinct chapters. The road enters the Arvan valley and gains height unevenly, with downhill interruptions that make the average gradient a poor guide to the work ahead. Across 28.4 kilometres, steep climbing, easier stretches and descents prevent a single rhythm from settling for long. The changing profile is part of the attraction: progress feels like a journey through the valley rather than a continuous ramp towards a distant sign.

Saint-Sorlin-d’Arves marks the transition to the final mountain section. Beyond the village and ski buildings, the road climbs into open slopes, with the Aiguilles d’Arves providing a distinctive backdrop. The last part is more sustained than the broken middle section, and the bends reveal how much climbing remains above the roofs. Reaching the col brings the separate efforts together into a particularly varied Alpine ascent.

01 / The ascent

Elevation profile

Start 597 m · Summit 2,044 m

Gradient by distance28.41 km / 1,448 m gain

0 km5.7 km11.4 km17.1 km22.8 km28.4 km

02 / The crux

Where it gets difficult

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

Steepest 500 m average

10.3%

Where to find it

8.70–9.20 km from start

Net height gained: 52 m
Section length: 500 m

The whole climb28.45 km

0 kmFinish

03 / The numbers

Climb statistics

Distance: 28.41 km
Elevation gain: 1,448 m
Average gradient: 5.1%
Climb category: HC
Start elevation: 597 m
Summit elevation: 2,044 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 58 min

Power throughout: 225 W
Average speed: 14.4 km/h

Based on the 28.45 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