Author: Tom Epton

All you need to know about the 2022 National Hill Climb Championships

On Sunday the 30th of October, the men and women of Britain’s unique hill climb scene will be taking on the DO/604 climb battling it out for the coveted National Hillclimb Championships in Wales! The climb is known as “Old Shoe”, running parallel to Horseshoe Pass –  a better known climb along an A-road, however Old Shoe is steeper and shorter. The climb’s main statistics are…

  • Length: 1.55km 
  • Average gradient: 12.5% 
  • Maximum gradient: 15% 
  • KOM: 5 min 47s, 2,016m/h VAM 
  • QOM: 6 min 58s, 1,673m/h VAM 

It’s short and steep. I imagine the Strava leaderboards will be disrupted somewhat this weekend, especially with the forecasted tailwind. 

Course Forecast

You can see the forecasted course here in detail but here are the broad strokes… 

  • It’s nicer than last year!

    For those of you that remember, the National Hill Climb champs last year were raced in biblical conditions. This year, no such conditions shall occur. The weather will actually be quite pleasant for the duration of the event. It will be between 11 and 13 degrees for most riders with a chance of rain but it may remain dry.
  • Tailwind all day 

    Every rider will have a tailwind that will pick up slightly during the day. We can even use a myWindsock forecast to see how much difference that will make. Let’s see how we do that.

Introducing our virtual rider

I would like to introduce our virtual test rider, we shall name them Sam. Sam and their bike is 70kg and has 350W for the duration of the course. We will run two little tests on our virtual rider to demonstrate some of the power of myWindsock! If you wish to have a proper route around, premium features on this forecast are available for free!

What happens if Sam starts at 9am or 10am? 

Well, the wind direction doesn’t change at all and it picks up from a forecasted 5.1m/s at the time of the first rider heading off, peaking at 5.6m/s and dropping back down to around 5m/s for the last few riders.

  • 9am start : 6 minutes and 37 seconds
  • 10am start: 6 minutes and 36 seconds
  • 1pm start : 6 minutes and 38 seconds

We see very small differences within the error window for forecasting. It seems the weather will not make a huge difference come race day.

How should Sam pace the effort?

myWindsock allows us to accurately and confidently predict our performance. As a result, we can go in feeling prepared.

The gradient changes throughout – with the steepest portion at the top of the climb. We can also see a dramatic flattening of the climb in the last minute of the effort. Gradient is just one of a number of metrics we should use with a general rule of thumb being to go harder on the steeper sections and easier on the flatter sections.

Should Sam stand up or sit down? 

Aero matters in a hill climb. If we stand up our rider’s cda changes from 0.30 up to 0.37 – this is a huge aero penalty. What time difference does this make in our scenario?

  • Stood up : 6 minutes and 36 seconds
  • Sat down: 6 minutes and 40 seconds

We have barely scratched the surface of what you can do with myWindsock as a means of predicting your performance. If you want ultimate confidence and a host of features click here to sign up!

Why do you ride faster when it’s warmer?

This weekend, it will be unseasonably warm for many of Britain’s cyclists meaning the summer kit might just get one more run out – plus a waterproof layer or two. One thing you might notice though, is that you tend to go a little faster in the heat. Why is this? 

The first reason is quite an obvious one, you’re wearing less clothes. A jersey and shorts is much tighter fitting than a winter jacket. That flapping in the wind costs energy – as the jacket presents a larger surface area and increases the amount of turbulent air. But, cold air itself is actually slower too!

Why is cold air slower?

If we have a think about the aerodynamic equation which governs how the force on something changes as it moves through the air under various conditions we notice that the power re quired to move our bicycle is proportional to the density of the air. Air density is not static, some air is more dense than other air. Remembering our GCSE science, we know that density is directly proportional to pressure – and pressure is proportional to temperature! This means, on a hot day, the air is less dense.

Why is less dense air faster?

Density is a quantity which describes how much of something takes up a given space. The density of air describes how many air particles are in any given square metre of space. If the air is less dense, there is less air to ride through. This is the reason many record attempts take place at altitude. With less air to ride through, it’s much easier to go faster!

If you’re out on your bike this weekend, you might see a notable uptick on your average speed. If you’re interested in how the weather can impact your riding or want detailed, up to date forecasts – sign up to Mywindsock for free here.

Tom Epton introduction

Hi! My name is Tom and you’ll likely see a bit of my work on the Mywindsock blog and social media channels over the next few weeks, months and maybe beyond if I do a good job. I write a little bit for Cycling Weekly writing about tech and fitness, as well as writing for other places including Yellow Jersey’s blog, Training Peaks coaching blog and a few bits all over the place. I also work as a data scientist. I have a physics degree that I managed to obtain in 2020 despite my best efforts to ride my bike instead of working while at uni!

Away from work, you’ll often find me racing in triathlons and other multi-sport events. This year, I even managed to race at a couple of championships as an elite athlete for GB which was very exciting. I did not fare particularly well. I have five interests in my life, swimming, cycling, running, working, eating. It sounds kind of boring when you put it like that, but I have fun all the same. I’ve been lucky enough that my work, and triathlon, has taken me to some amazing places and my intention is for this to carry on as long as possible – but now I shall do so with the best weather forecasts in the business!

This winter, I plan to take up mountain biking, as well as spending a bit of time bike packing – I know for this, mywindsock forecasts will come in very handy helping me with route and tyre selection!

If you have any questions, corrections or anything you want to ask me you can drop me an email at tom.epton@mywindsock.com or follow me on Instagram and send a DM! I don’t bite.

Kona Windsock Forecast

In this blog, we take a look at the Kona bike course and how the weather might play a role in today’s Women’s Ironman World Championships.

The Ironman World championships are taking place in Kona, with the women’s race starting at 5:25pm UK time today and the men’s race taking place on Sunday evening. Amateur races are taking place today. The bike course in Kona is boring, on paper, but the weather can play a role. In Ironman branded triathlons, athletes are allowed to ‘half draft’ at 12m behind the rider in front of them. This can make a significant difference to the amount of power required to hit any specific speed. Fortunately for strong bikers, there are often cross winds! These are so strong that disc wheels are actually banned for this race.

Why do cross winds help stronger riders?

When you’re riding along a road, your speed is determined by the amount of force being pushed through the pedals and the amount pushing you back (in the form of air resistance). Having a rider 12m in front of you will decrease the amount of air that you push out of the way – this is because the rider in front is doing it for you. If you have a train of riders, which tend to form at Kona, further down the group riders are ‘hardly pedalling’, in the words of Alistair Brownlee. Cross winds provide a component of force from a new direction, a direction which is not protected by the rider in front. This reduces the impact that a (legal) drafting train will have – suiting the stronger riders more.

Today’s Kona forecast

If you want to take a look at the Kona forecast – take a look here!

The course in Kona is not particularly hilly, with only a small amount of elevation and no steep gradients. This means that the wind is the main player in breaking up the race (other than the swim). By making use of myWindsock’s planner feature, we can work out the point in the course where the weather will have the largest impact.

In Kona, the fastest women will dip under 5 hours on the bike. As these will likely be the main contenders we will use a bike split in this region for our model. This is the sort of numbers you might see, obviously there will be athletes both slower, faster, more aero and less aero than this. 

One thing we notice is the ‘wImpact’ score of 3.3%, this means that an athlete has to ride 3.3% harder than they would on a day with no wind. This is remarkably low for Kona, which usually is heavily impacted by the weather.

The most interesting part of this course, and the point where stronger riders will attack, is around the halfway point. This is what’s shown in the picture. In the kilometres leading up to Hawi and back there’s a light cross wind, but it’s also a drag uphill to the turn around. This will be the point during the course where the drafting effect of the train will make the least difference. Expect the attacks to start around Waikoloa and last until the end of the bike leg. The headwind on the way back will potentially serve to bring groups together slightly, but it’s only light. If the race hasn’t split up by the time they get back to Puako after the climb to Hawi, it’ll likely be a running dominated race! Expect to see some quick times with the light winds and potentially a new bike course record from Daniella Ryf.

If you want to have a play with the Kona forecast, have a look here!