How many watts does it take to climb? Enter a rider’s climbing time and weight: the timer gives you watts per kilo, always as a range, and VAM, the meters climbed in an hour.
On Saturday, October 10, Il Lombardia will be decided on the final climbs around Como. When the climbing times come up during the live broadcast, enter them below.
Civiglio
4.2 km 9.7% average 406 m elevation gain
Enter a rider’s climbing time: the watts per kilo, with their range, and the VAM will appear here.
W/kg approx.
between and W/kg
- VAM
- m/h
- Average speed
- km/h
- Power
- about W
| Power | Time | Speed |
|---|---|---|
| 5.0 W/kg | 16'40" | 15.1 km/h |
| 5.5 W/kg | 15'17" | 16.5 km/h |
| 6.0 W/kg | 14'08" | 17.8 km/h |
| 6.5 W/kg | 13'10" | 19.1 km/h |
| 7.0 W/kg | 12'20" | 20.4 km/h |
How we calculate it
Physical model by Martin and colleagues (1998): gravity, rolling resistance, air (on the rider and on the wheels) and bearing friction, at constant speed and gradient. Central assumptions: bike and equipment 8.0 kg, rolling resistance 0.0040, aerodynamic drag area 0.32 m², drivetrain efficiency 97.6%, air density 1.17 kg/m³ (average altitude 411 m), no wind.
The range is the result with all the favorable assumptions (drafting, a 1.5 m/s tailwind, a light bike) and with all the unfavorable ones (riding alone, a headwind, a heavier bike). These estimates are typically off by 6–10% (Millet, Tronche and Grappe, 2014): that’s why we never give a single number. A rider who surges and eases off spends a little more for the same time. VAM, the meters climbed in an hour, is a measurement instead: it depends only on elevation gain and time.
Length and elevation gain: official RCS Sport Race Guide 2026, climb profiles.
San Fermo della Battaglia
2.7 km 7.2% average 195 m elevation gain
Enter a rider’s climbing time: the watts per kilo, with their range, and the VAM will appear here.
W/kg approx.
between and W/kg
- VAM
- m/h
- Average speed
- km/h
- Power
- about W
| Power | Time | Speed |
|---|---|---|
| 5.0 W/kg | 8'31" | 19.0 km/h |
| 5.5 W/kg | 7'52" | 20.6 km/h |
| 6.0 W/kg | 7'19" | 22.1 km/h |
| 6.5 W/kg | 6'52" | 23.6 km/h |
| 7.0 W/kg | 6'29" | 25.0 km/h |
How we calculate it
Physical model by Martin and colleagues (1998): gravity, rolling resistance, air (on the rider and on the wheels) and bearing friction, at constant speed and gradient. Central assumptions: bike and equipment 8.0 kg, rolling resistance 0.0040, aerodynamic drag area 0.32 m², drivetrain efficiency 97.6%, air density 1.18 kg/m³ (average altitude 304 m), no wind.
The range is the result with all the favorable assumptions (drafting, a 1.5 m/s tailwind, a light bike) and with all the unfavorable ones (riding alone, a headwind, a heavier bike). These estimates are typically off by 6–10% (Millet, Tronche and Grappe, 2014): that’s why we never give a single number. A rider who surges and eases off spends a little more for the same time. VAM, the meters climbed in an hour, is a measurement instead: it depends only on elevation gain and time.
Length and elevation gain: official RCS Sport Race Guide 2026, climb profiles.
Why a range and not a single number
Physics takes you from climbing time back to power: gravity, tire rolling resistance, air resistance. But wind, drafting, position on the bike and actual weight aren’t known precisely, and they shift the result by 6–10% (Millet, Tronche and Grappe, 2014). That’s why we always give a range: the value with every favorable assumption and the value with every unfavorable one. A “6.12 W/kg” with two decimals would be a fake number.
VAM, on the other hand, is simply a measurement: meters of elevation gain divided by time. It needs no assumptions, and for comparing different climbs it’s often the most honest number.
What it doesn’t tell you
It doesn’t tell you who is the strongest, full stop, and it says nothing about how a rider prepared: a high number is a high number, not grounds for suspicion. It tells you what a climb cost, with the margin of error that comes with an estimate like this.