Monsal Head Hill Climb in Graphs 2021

It’s the iconic Monsal Head hill climb this Sunday. Let’s take look at the course and it’s conditions with a few myWindsock Graphs. Could this be the year Malcolm Elliotts 1981 Men’s course record (1min 14.2secs) is bettered?

Forecast as of 19:00 30th September 2021. View the latest Monsal Head 2021 Weather Forecast.

The Forecast

Let’s start with the basics. The overall forecast is, cool temperatures and a strong WSW wind, gusting from 18mph to 32mph.

A crosswind start turns gradually into a headwind by the finish.

The Course

The following myWindsock dynamics are computed for a record equaling 1min 14sec ride. 80KG total mass, 880Watts, 11Watts/kg.

For the first 12 seconds, most of the rider’s Wattage is contributing to accelerating to 45kmh. Then the gradient bites quickly.
Negative Air Speed during the first 30 seconds reduces air resistance. A higher air speed than ground speed, during the steepest section, increases air resistance.
Weather Impact% shows how much additional energy would be required to match the conditions of a weatherless day. Overall the wImpact% is 2.2%. This means to equal a weatherless day’s conditions, 2.2% more Watts would be required.

11Watts/kg is 11Watts/kg, right? Wrong.

On a climb like Monsal Head and the forecast weather conditions, a heavier rider with greater Watts, will better a ligheter rider who has the same 11Watts/kg required to hit the 1min 14.2Sec. The Delta Comparison Chart shows how the lighter rider loses time to the heavier rider.

Red line shows 70kg rider losing time to 80kg rider. Eventually losing 1 second overall.

Why is the lighter rider slower? Let’s compare the resistances.

The lighter rider has a greater proportion of their energy overcoming Air resistance than the heavier rider. This is because, generally speaking, the aerodynamic drag does not increase proportionaly to the rider’s weight. The additional wind resistance will act in the heavier riders favour.

So, how many extra Watts would a 70kg rider require to match the 80kg rider’s time?

An extra 0.2Watts/kg (15Watts) would be required to match the time of the 80Kg Rider. Air resistance mostly consumes the additional Wattage.

How good did Malcolm Elliott have it?

Using historic weather, we can look back to the recorded weather conditions for the 1981 Monsal Head Hill Climb.

18.9mph WNW.
Significant 8km/h reduction of air speed in first 45 seconds of ride.
Overall the myWindsock Weather Impact% for 1981 was 0.1%. This is favourable compared to the 2.2% wImpact% forecast for Sunday.

Big question, in 1981 what were the Watts/Kg required for an 80kg rider to record a 1min 14.2sec rider?

10.44Watts/kg. But, big caveat… This was 1981, clothing, tyres and the bike would have been less favourable than today’s equivalents.


The current forecast is significantly less favourable to that of 1981. This will make a record ride even more exceptional should the 40 year old record fall.

Check out the Monsal Head course yourself and make your own experiments.