How to get the Sa Calobra KOM…

Sa Calobra is a climb on the Island of Mallorca. It’s a well known testing ground for world tour pros and amateurs alike and recently, the GCN tech show have been talking about it! The steps to getting the record on this climb are as follows…

  • Step 1 – Have World Tour power to weight ratio
  • Step 2 – Profit

Ok, so the KOM is quite hard to get. But as the GCN fans amongst you might have noticed our feature on the Tech Show helping them out with some number crunching. The video is right here, but we will go into a little more detail on some of the plots and graphs below…

Stand up or sit down?

Many of you will probably have observed that when you stand up on the bike, you can produce a few extra watts. The downside to this is that you present a larger frontal area to the wind. As a result, depending on the wind direction and the gradient, either can be faster. It’s not as simple as “always sit” or “always stand”.

If it’s steep, you’re going slower and thus get less aero penalty for standing up. In any scenario where your wind speed is low, if you can put more watts out standing up it’s likely faster to do so. Remember, your wind speed and ground speed are not the same! In headwind sections, even when climbing slowly, sitting is likely your best option as air resistance will be a significant portion of total resistance.

When should I go?

Now we know whether or not we should stand up or sit down (well, we should do both depending on where we are on the climb) it seems wise to figure out when we should go. Mallorca, being a small island, is quite exposed to the elements and weather can make a big impact.

We modelled the current KOM ride, at the same time of day, for everyday of 2022.

In 2022, the slowest day for an attempt was in March and the fastest day mid September. generally speaking it gets slightly faster the later into summer you get but the difference in conditions can vary a lot from one day to the next. Late August and early September seem like good times to go and have a bash at the segment.

What time would you do on Sa Calobra?

Why not give the myWindsock modelling a whirl. Find out what your best time up Sa Calobra would be, view the Sa Calobra Segment.

If you like this analysis, and want to learn more about the features available to you when you sign up to myWindsock, have a look here.

Aero Testing with myWindsock

Aero field testing is available to all Premium members with power meter data by simply viewing their Strava Activity Weather or uploading a TCX file. Learn more about Premium.

When you head out to do an aero test using myWindsock, there’s always a question of how much you can trust your results. We understand this and have a tool for this in our aero test mode – confidence!

In the above image you can see that the rider (Ben) alternated between two positions. The first two runs went reasonably well and the Orange Test Range around the Test Average is very narrow. I had enough good consistent loops and the bad loops were detected well by the filter. This is a test with ‘High Confidence’. The narrower the confidence bar, the lower the variance between calculated cda values. The aim, when doing an aero test, is to make this range as narrow as possible.

Top 5 reasons you have a high test range

  1. Traffic at turns – Leaving your position or using the brakes on a large number of your loops will cause a high Test Range. Choose quieter times of day or ensure a greater quantity of good loops vs bad. Ensure when you do use your brakes you use them sufficiently enough to greatly impact the loop CdA otherwise it may not be filtered and make its way into the test range, take the opportunity to sit up and relax before the next loop.
  2. Traffic passing – Your CdA is affected by traffic in both directions. Oncoming traffic will increase your CdA whilst traffic passing you in the same direction will decrease your CdA. Choose times of day that have the lowest or most consistent level of traffic. If you suspect a bad loop due to traffic brake to a stop to demonstrate to the loop filter that it is a bad loop.
  3. Gear changes – Changing gear will change your drive train efficiency. If you do have to change gear (ideally don’t) make sure you always change at the same location. Do not change loop to loop and test to test. Pick a gear, make a note of it, check that you’re in it and leave it.
  4. Insufficient test loops – If you have a really good test loop, a velodrome for example, you can get away with a handful of loops per test. If however you aren’t that lucky more loops are required. Remember using a short loop will isolate problems and speed up your test. 
  5. Position discipline – Make sure you are paying attention to your position. Doing some loops relaxed and some loops focused will lead to a wide range. Small changes to position are too subtle to be weeded out by the loop filtering process and will therefore produce a large Test Range.

    Aero field testing is available to all Premium members with power meter data by simply viewing their Strava Activity Weather or uploading a TCX file. Learn more about Premium.

This blog post was written by Ben back in 2017 but has been adapted and reposted in November 2022!

Windsock beyond time-trials

Any reader of this blog will likely understand the virtues of myWindsock for athletes looking to improve their performance. We know the detailed forecasts can allow us to pace races optimally, target Strava segments and figure out where to attack. The performance aspect of myWindsock is used by world class athletes to break records and win olympic medals. 

Most of us have no chance of making the Olympics, most of us will not be breaking the North Coast 500 record and most of us aren’t even trying to break personal bests over ten miles most of the time. Primarily we just enjoy riding our bikes. Racing is a huge part of what inspired myWindsock, but we aren’t only a tool for racers. The one thing all cyclists have in common is that they enjoy riding their bike. 

That enjoyment varies by ride, let’s not pretend we enjoy getting soaked in British lanes as much as we enjoy railing alpine descents in the sun. We don’t. However, it’s easy to enjoy cycling without rain and wind. The real challenge is learning to enjoy riding on the roads of the UK throughout the miserable months. I’m writing this on the 14th of November and the next time I plan to get back on my bike is the 16th and I plan to avoid the rain! 

Planning what to wear 

I live in a relatively small flat with a small washing machine – as a result, I have to plan my kit a little in advance. One thing that helps, is deciding what to wash with the assistance of an accurate weather forecast. I live in Southampton and tend to ride in the New Forest, of course the weather can vary quite a lot over the course of a 100km ride, so rather than checking the weather in every town that I’m planning to ride through I shall use a windsock forecast.

As we can see, I shall possibly be getting wet but the temperatures aren’t particularly cold. As a result, I’ll locate a breathable, packable raincoat to avoid the ‘boil in the bag’ effect of my sturdier ones! On top of this, I’ll probably get my legs out and wear my waterproof bib-shorts.

The interesting thing is, despite being extremely interested in performance, I use myWindsock for this purpose more often than I use it as a means of predicting performance. Let’s face it, we all train a lot more than we race – even if we don’t train much at all.

Planning where to go

Ok, two weather related factors of rain and temperature have been taken care of and we know what to wear. But there’s still one open question – where should we go? I never used to bother with wind direction on rides but, thanks to my mate Harry, I’ve become addicted to the “tailwind home”. Obviously, you feel much worse at the end of a ride than you do at the start – you’re tired, ready for a shower and a snack and the last thing you need is a headwind for the final 10 miles. Luckily, myWindsock has us covered. Let’s take a look at the route map… 

Blue means tailwind, red means headwind. The arrows show us where the wind is pointing in any direction. Generally speaking, the New Forest is pretty flat and the wind is the main thing that provides riders with resistance. We can see from this that, broadly speaking, I’ll have a headwind at the start and tailwind on the way home.

With it being a loop, we have mostly an even split in wind direction. The distribution of wind directions can be seen on the “Apparent Wind Direction” plot and the proportion of Tailwind to Headwind can be seen below this.

Using myWindsock is not the preserve of elite athletes. Sure, it’s a great tool for them – probably the best! It’s a great tool for anyone heading out on their bike too. I know that on the Wednesday ride, I’ll be doing my turn on the front in the last half of the ride with the tailwind. We can help you pick the right kit, pull the easiest turns and time your segment hunting to perfection. If you’re interested in signing up, many of the best features of myWindsock are available on our free version. Take a look here to sign up! 

National Hill Climb: The Winning Margin

On Sunday, the weird world of Hill Climbing got together to launch themselves up the Old Shoe in Wales. We were there watching, with Ben (the myWindsock big boss) propping up the famed orange banner on the climb. The headlines were that Andrew Feather took first place in the men’s race in a time of 5:29.5, the women’s race was won by Illi Gardner in 6:46.6. 

The men’s race – headline statistics

In a closely fought men’s race, the top 15 were all separated by about 45s…

1 Andrew Feather, Hunt 05:29.5 Senior

2 Tom Bell High North Performance 05:31.9 Senior

3 Richard Bussell AeroCoach 05:47.8 Senior

4 Patrick Clark Team Lifting Gear Products 05:52.9 Senior

5 Ed Laverack Backpedal 05:53.3 Senior

6 Cameron Biddle Bikestrong-KTM 05:55.7 Senior

7 Kieran Wynne-Cattanach Team Lifting Gear Products 06:01.3 Senior

8 Will Lowden WattShop 06:04.8 Espoir

9 Leon Wright Race Hub 06:07.8 Vet

10 Giles Drake Wheelbase Cabtech Castelli 06:08.6 Senior

11 Andy Cunningham Wheelbase Cabtech Castelli 06:10.3 Senior

12 Harry MacFarlane GFTL 06:10.8 Senior

13 Gabe Dellar Southampton University Road Cycling Club (SURC) 06:11.6 Espoir

14 Jude Taylor Team PB Performance 06:12.4 Senior

15 Archie Cross Bristol Road Club 06:14.9 Senior

The winning margin was tiny too – Andrew Feather just about beat Tom Bell with a narrow gap of 2.36s. To overcome this gap, any of the following would have done the trick assuming Tom is 63kg riding at 400W…

  • Tom to push 3.5 extra watts
  • Tom’s system weight to be 500g lighter 
  • A reduction in Tom’s cda by 0.035 

Cycling is a sport of narrow margins and a small reduction in performance can be the difference between a national championship and second place, as we saw here. With small margins like this, top athletes place a premium on the certainty provided by myWindsock – which you can find more on here

The women’s race – headline statistics 

The women’s race was a more open affair with bigger gaps being seen across the top 15…

1 Illi Gardner Wahoo Endurance Zone p/b Le Col 06:46.5 Senior

2 Mary Wilkinson Team Boompods 07:09.8 Vet

3 Bithja Jones Pankhurst Cycles 07:11.0 Vet

4 Frances Owen Wahoo Endurance Zone p/b Le Col 07:22.6 Senior

5 Alex Morrice Team LDN 07:43.7 Espoir

6 Abi Plowman Kendal Cycle Club 07:45.5 Senior

7 Rebecca Richardson Team Brother UK 07:51.1 Senior

8 Sara Willhoit Paramount CRT 07:56.8 Senior

9 Lucy Harris Team Boompods 07:57.9 Senior

10 Lucy Lee Team LDN 08:00.2 Senior

11 Joanna Blackburn High North Performance 08:00.9 Senior

12 Natalie Stevenson Glasgow Ivy CC 08:03.2 Senior

13 Madeleine Heywood FTP ( Fulfil The Potential ) Race Team 08:08.5 Senior

14 Lizi Brooke Wahoo Endurance Zone p/b Le Col 08:16.6 Senior

15 Alison Dockney Macclesfield Wheelers 08:16.8 Senior

Illi Gardner was on a stormer, putting a whopping 23.3s into Mary Wilkinson in second. Illi Gardner maintained a VAM (climbing rate) of 1736m/hr for her effort. This is around the climbing rate that Tadej Pogačar would hold on a medium length climb at the end of a stage – Illi has put in a fully nuclear performance here! 

Big congratulations to our own supported riders in this year’s event. Especially to supported team, Team Lifting Gear Products, who yet again took the Mens Team Prize. We had stellar performances from all our supported riders from Team Lifting Gear, FTP Racing & Congleton CC.

The national hill climb championships mark the end of the British racing season on the road with only a couple of smaller events left. It has been a great year with many wonderful events. All of us at myWindsock are excited to help athletes again reach new heights in 2023!

Click to view the conditions and predict your National Hill Climb 2022 time.

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 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!