French Alps, France · from Saint-Jean-de-Maurienne
Col de la Croix de Fer
Tour de France 2026 · Stage 20 →The Croix de Fer from Saint-Jean-de-Maurienne is a long, irregular alpine journey: steep opening ramps, two genuine descents in the middle, and a hard finale past the Grand Lac. The changes of rhythm make it far more tiring than its average gradient suggests.
Summit elevation: 2067 m
Route overview
Col de la Croix de Fer · from Saint-Jean-de-Maurienne
Schematic road geometry from the routed track, with 21 detected hairpins marked (filled markers are tighter than 15 m radius). Use it to see the shape of the climb, not for navigation.
Measured road detail
Taken from the Col de la Croix de Fer track used by the 3D flyover: from Saint-Jean-de-Maurienne · 1,430 road points
- Measured length
- 28.3 km
- Measured ascent
- 1708 m
- Elevation range
- 564 → 2067 m
- Hairpins detected
- 21
- Tightest hairpin
- 4.3 m radius
- Surface
- paved
Tightest hairpins on Col de la Croix de Fer
- 5.6 km · 747 mRight · 9.5 m
- 21.6 km · 1518 mRight · 4.3 m
- 23.8 km · 1710 mLeft · 10.1 m
- 25.3 km · 1831 mLeft · 10 m
- 25.7 km · 1862 mRight · 7.2 m
- 26.4 km · 1921 mLeft · 10.6 m
Hairpins and elevations are derived from the routed track; road data © OpenStreetMap contributors (ODbL).
How fast would you climb Col de la Croix de Fer?
Enter your power and weight. A physics engine calculates your estimated time against the gradient profile.
Predict your
performance.
See how power and weight affect your time on a real climb.
*Demo simulation uses standard road bike physics (CdA 0.32, Crr 0.004).
Col de la Croix de Fer and the Tour
First crossed by the Tour in 1947, the Croix de Fer and its twin the Col du Glandon (2 km from the summit) have appeared dozens of times, usually as the opening act of the Alps' hardest stages. The iron cross at the summit gives the pass its name.
A fixture of the Marmotte granfondo and of Tour stages into Alpe d'Huez. In 2026 it opens the mammoth stage 20 from Bourg-d'Oisans, ahead of the Télégraphe, Galibier and Sarenne.
Richard Carapaz won the queen stage over the Croix de Fer, Télégraphe, Galibier and Col de Sarenne, sealing the mountains classification.
Led the first Tour de France crossing of the Croix de Fer in the 1947 Grenoble-Briançon stage.
Riding it yourself
When to go
Open roughly June to late October. The upper basin is exposed; the mid-climb descents make arm warmers welcome even in summer. September is the quiet-roads sweet spot.
Base & logistics
Saint-Jean-de-Maurienne is the base for this side, Le Bourg-d'Oisans for the other. Water in Saint-Sorlin-d'Arves near the top. Pair with the Glandon summit (a 2 km detour) or descend the far side towards the Alpe d'Huez valley.
FAQ
How long is the Col de la Croix de Fer climb?
From Saint-Jean-de-Maurienne, the climb is about 27.1 km with roughly 1575 m of elevation gain at 5.8% average gradient (based on the simplified profile used by this simulator; published figures vary slightly by source).
How long does it take to cycle up Col de la Croix de Fer?
It depends almost entirely on your power-to-weight ratio. Use the simulator on this page: enter your FTP and weight, and a physics model (air resistance, rolling resistance, gravity) estimates your time on the gradient profile.
Can I see Col de la Croix de Fer in 3D before riding it?
Yes. The route overview on this page has a 3D flyover that follows the real road: 1,430 routed points covering from Saint-Jean-de-Maurienne, with terrain, gradient and the road's own bends. It runs in the browser, no account needed.
How many hairpins does Col de la Croix de Fer have?
21 hairpin bends are detected on the routed track, the tightest turning inside a 4.3 m radius. They are marked on the 2D sketch and ridden in order in the 3D flyover.
How accurate is the time simulation?
The simulator uses a simplified segment profile and standard road bike assumptions (CdA 0.32, Crr 0.004, 8 kg bike). It does not model wind, drafting, altitude, surface or pacing errors, so treat the result as a realistic estimate, not a guarantee.
How should I train for Col de la Croix de Fer?
Sustained climbs reward steady threshold and sweet spot work plus a power-to-weight improvement over weeks, not days. TrainCraft builds structured cycling training plans and adapts them when you miss sessions, using fatigue science (CTL/ATL/TSB).
More famous climbs
Preparing for this climb?
A climb like this is won weeks in advance. TrainCraft builds a structured plan around your FTP and available hours, and adapts it when you miss a workout.
Start Training FreeThe profile is simplified into 52 segments for simulation; real gradients vary metre by metre. Stats shown are derived from this simulated profile and closely match commonly published figures. Time estimates assume standard road bike physics and no wind.
Training for a climb like this?
TrainCraft builds structured training plans and adapts them when life gets in the way — real fatigue science (CTL/ATL/TSB), visual workout builder, Strava & Garmin sync. Free to start.