National 24 hours championships – how far is possible?

We’ll start this blog with a caveat, this forecast is not an accurate prediction but a rough guide of the speed the riders might get come race day out of their 24 hour TT effort. The gpx file used to make the forecast essentially covers one lap of each leg, which come race day the riders will cover multiple times. The file that we’ve used for this is a total distance of 197 km and there’s a couple of things that will increase the uncertainty of these forecasts.

Caveat number 1 – The Road Surface

myWindsock allows users to set the rolling resistance during their forecast, which on a TT where you know exactly the route, you can make a reasonably educated guess at. However, during a 24 hour TT the riders will be doing multiple laps of the various legs so it’s quite difficult to know whether they’ll end up doing 3 laps of the leg with the dodge road surface and 5 laps of the leg with the amazing (for Britain) road surface or vice versa. 

Caveat number 2 – the wind

It won’t surprise you to know that the wind, during a 24 hour time trial, can change quite dramatically. In the UK, average wind speed over the day and prevailing patterns follow some consistent trends due to the country’s maritime climate and westerly wind influence. Usefully, the National 24 hour championships are in July. July near Wrexham brings relatively calm conditions, with average winds between 7–13 mph (≈11–21 km/h). The most reliable data suggests a typical value around 9 mph, making it the least windy month of the year.

Even with relatively low winds, there will be legs that have faster wind conditions than others and we don’t know the proportion of time riders will spend on each loop and such. That said, using all loops equally with average historical wind data for the date of the event may actually average out all of these problems and we could get a reasonable estimate.

How to win

Now the caveats are out the way, let’s turn to how we might go about winning this race. 

In 2024, the National 24 hour TT championships were won with 426.19 miles for the women and 546.36 miles for the men. In 2023 the men’s top three covered between 501–519 miles with the women’s podium riding between 381 and 465 miles. Hard to know exactly how far you’ll have to ride in order to podium this year but the men will most likely need to exceed 500 miles and the women will need to exceed 400. 

This is the average speed required for a given distance over 24 hours – bare in mind that this also includes fuelling and toilet stops.

Now we have the speed, let’s check out the power needed for each of these speeds. For the sake of this forecast, I’ll use a 72kg rider with a 10kg bike, no pacing rules but sitting up on the climbs. If you want to plug your own numbers in, you can sign up to myWindsock here.

Using a myWindsock forecast of the course we can see how much power we need to ride at various speeds. Please bare in mind the values inputted to the forecast will not be your own but you can sign up to myWindsock here and have a go yourself.