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Col de l'Iseran: the climb, its Grand Tour history and records
Col de l'Iseran: each side of the climb, every Grand Tour passage since 1996 and the records, each figure with the source it comes from.
The climb
Auvergne-Rhône-Alpes (Savoie), France
| Side | Start | Length | Elevation gain | Average | Max | Summit | Hairpins | Source |
|---|---|---|---|---|---|---|---|---|
| Val-d'Isère (north) | Val-d'Isère | 16.1 km | 947 m | 5.9 % | 9.2 % | 2764 m | 8 | climbfinder.com |
| Bourg-Saint-Maurice (north, full, via Val-d'Isère) | Bourg-Saint-Maurice | 47.4 km | 2050 m | 4.3 % | 8.6 % | 2770 m | 12 | climbfinder.com |
| Bonneval-sur-Arc (south) | Bonneval-sur-Arc | 13.2 km | 976 m | 7.4 % | 11.5 % | 2764 m | — | pjammcycling.com |
| Lanslebourg (south, full, via Bonneval-sur-Arc) | Lanslebourg-Mont-Cenis | 32.1 km | 1446 m | 4.5 % | 10.5 % | 2764 m | 5 | climbfinder.com |
Each side from one source, linked. A dash: the sources we opened disagree or give no figure, so we leave it out.
In the Grand Tours since 1996 2
| Year | Race | Stage | Type | Stage winner or first over the top | Source |
|---|---|---|---|---|---|
| 2019 | Tour de France | 19 | Crossed | Egan Bernal | en.wikipedia.org |
| 2007 | Tour de France | 9 | Crossed | Yaroslav Popovych | en.wikipedia.org |
Records
| Record | Rider | Time | Year | Source |
|---|---|---|---|---|
| Bonneval-sur-Arc: fastest race ascent (watts2win segment 13.03 km, 7.35%) | Egan Bernal | 0:35:48 | 2019 | watts2win.eu |
A time is listed only where the sources agree on it; where two sources give different times for the same ride, it is left out.
How long would it take you?
Your time up Col de l'Iseran at a steady power, from a physics model.
Advanced: rolling resistance and drag
Estimate from a physics model (Martin et al. 1998), on the average gradient. Wind, surface, pacing and steep sections change the real time. More cycling tools
How this is calculated
P × 0.977 = ½ · ρ · CdA · v³ + v · m · g · (sin θ + Crr · cos θ), θ = arctan(average gradient), m = rider + bike, g = 9.81; solved for the speed v, time = length / v. Air density ρ: NASA GRC troposphere: T=15.04-0.00649*h; p=101.29*((T+273.1)/288.08)^5.256; rho=p/(0.2869*(T+273.1)); h = mean of start and summit altitude. Sources: Martin et al. 1998, J Appl Biomech 14(3):276-291 — https://collections.lib.utah.edu/ark:/87278/s6jd5f71; Defraeye et al. 2010, J Biomech 43(7):1262-1268 (upright position, cyclist+bike 0.270 m2) — https://lirias.kuleuven.be/retrieve/232736; NASA Glenn Research Center, Earth Atmosphere Model (metric) — https://www.grc.nasa.gov/www/k-12/airplane/atmosmet.html. Climb geometry: the side's source in the table above.
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