Critical Power

myWindsock uses W’ Balance to help you pace race efforts correctly. W’ Balance allows you to maximise the work done above critical power (CP), but what exactly is CP? 

What is CP?

Critical power is the idea that the power duration curve can be fit to an equation which is approximately true for all athletes. Obviously, it’s more true for some athletes than others (there are statistical anomalies in any population). The point at which this approximation is no longer true will be somewhere between 30-60 minutes where the curve will tend toward a straight line – this line is where your critical power sits. 

The area between this curve and the CP line is your W’ – this is the amount of energy you have available above your critical power. You can use it all in one go with a big sprint, or burn it slowly with extended time just above critical power. 

How do I test it? 

You can test your critical power by doing two power tests and fitting a curve to the results of these tests. High North have quite a neat CP calculator available on their website. The favoured duration amongst coaches seems to be 3 minutes and 12 minutes. If you’re a 10 mile time trial specialist you might wish to do a 20 minute test as this is closer to race duration. Having more data points will also mean your CP value is more accurate so doing 3 tests might be better.

The W’ Balance tool

A more detailed description of how this works can be found here but we shall briefly discuss the tool here.

You can see in the graph that time spent above Critical Power depletes W’ and this is why having an up to date CP value is important for pacing – you don’t want to risk blowing up before the end or finishing with lots in the tank. 

If you like pacing tools and racing with confidence, you can sign up to myWindsock here! If you want a more detailed explanation of Critical Power, or any other metric on myWindsock get in touch with us via our social media.

Why are winter time trials so much slower?

It’s January which means one thing only – TT season is round the corner (ok maybe it also means other things). Races are popping up from mid February which means some early season form testing is on the cards. You might find that, as a result of a really consistent winter, your power numbers are really good this time of year yet you churn out a couple of slow time trials before it warms up. New kit, new bike fit, more watts and still going slower, but why? Winter time trials are slow!

Rest assured, it’s probably nothing to do with how powerful or inherently aero you actually are yourself and is more to do with the conditions. Of course, by subscribing to myWindsock you will have confidence in knowing this as the conditions are taken into account and you’ll know it was a slow day with high Weather Impact.

Cold is slow!

The speed you ride at for a given power on a given day with some given cda is proportional to one over the square root of the density of the air that you’re riding through. This basically means that as air density goes up, our speed will go down. Air density is impacted primarily by temperature. Hot molecules move faster and spread out more. This means more air occupies some given space when it’s cold compared to when it’s hot. In a time trial, the amount of space we need to pass through is fixed at the distance of the race, but the amount of air occupying this space varies quite a lot from one day to the next. 

If you have left your house at any point since October, you might have noticed it’s become rather chilly. As time trialists, we think “gosh, the air is rather dense today” and people look at us like we have just started speaking Spanish. Cold days are slow days. It’s just the laws of physics. 

If it’s slow, what’s the point of racing in February? 

Time trialing is part art, part science. The ratio of art to science will vary depending on who you ask but everyone agrees, to get good at time trials you have to do them. As with anything though, blind practice only gets you so far. Practising with purpose is the key. 

What would be handy is some kind of service which analyses your winter time trials and tells you how much impact the weather would have and how aero you are. Of course, you can see all of that information here. 

Use myWindsock to dial in your pacing and kit choices so that by the time summer comes around you’re dropping massive PB performances with confidence. 

Taking a World Tour KOM with the weather forecast

Back in September, I had a crack at taking a KOM off a world tour pro on quite a long climb. The pro in question was a Frenchman by the name of Thibaut Pinot. I wrote the whole story of the attempt in Cycling Weekly and you can read about it here but I didn’t cover the difference in conditions that me and Pinot faced. I’ve always been slightly suspicious that he had a slower day, as that would go some way to explaining the huge power gap that was overcome.

The segment 

It’s a very long drag. The kind of climb that might even be faster on a time trial bike – especially if there’s no weight penalty as in my case. However, I rode it on the road bike as Thibaut did. It starts in the town of Saint-Gervais les Bains and finishes up at an alpine airport (an altiport) past Megeve. 

To decide who had the fastest day, we will take a look at the various conditions and see who has the lowest wImapact%. This will tell us how much faster or slower the weather made us, a higher wImpact% means a slower day (a 5% wImpact% means we’d have been 5% faster on a windless day, for example). 

The pacing plan was to make use of the gradient changes. This segment doesn’t really turn into a ‘proper climb’ until 10 km in. This meant that the aim was to get to  this point having used as little energy as possible and we will go on to talk about how that was achieved later.

Thibaut’s day

Taking a look at the map we can see that Pinot had a headwind on the early part of the climb, crosswind in the middle through Demi-Quartier to Megeve and finally a cross-tail up to the altiport. Broadly, the conditions he faced were relatively neutral in the sense that there was no dominant headwind or tailwind. 

Thibaut Pinot had a wImpact% of 2.2% on the day that he took the KOM. He rode up the climb in a time of 40:31. 

My day

I had a wImpact% of 1.8% on the day that I took the KOM. I rode up the climb in a time of just over 39 minutes. My day was 0.4% faster than Pinot’s – so how did I manage to put around 3% into his time? Let’s take a look at the wind map from my day. 

I had a very light headwind basically the whole way up. So, how did I do it? 

Well basically we cheated a little by using my mate Harry to place the flatter sections. Here’s an excerpt from Cycling Weekly which explains our method.

Harry paced the flatter sections for me. We avoided using the car for aero assistance as that felt unfair but, luckily for me, Harry provides a similar draft zone to that of a Peugeot Traveller and has a good amount of watts to offer up alongside, making him a perfect team-mate.” 

This meant I could put all of my energy into matching Pinot on the steeper sections where the wind matters less and had Harry on the front on the flat, headwind sections meaning that he is the reason we took the KOM. 

Even on a climb like this, air resistance was around 15% of the total resistance that I faced during the attempt. This is worth minutes and paints an interesting picture as to how important things like drafting and aerodynamics are on climbs, even at relatively low speeds of 25-26 kph as they were in this attempt. I am not faster than Pinot, despite outperforming the weather! 

If you want to take a KOM off a world tour rider, you might wish to do so with the assistance of myWindsock. We can help you go into attempts like this with confidence and you’ll know what power you need to do for what duration for a given outcome. You can sign up here.

Adding a forecast to your planner

Often, we have a series of routes that we ride regularly. Each rider and club has their own version of these but the pleasure of the loop can depend quite heavily on the weather. One way to pick the best loop for a given day is by adding a forecast to your planner. From the planner you will see a summary forecast for each scheduled route.

View your week’s weather

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If you click on the given activity, you’re able to see a complete analysis but the summary information presented can be enough to make a decision on a given day if you know the route well. This can be done on the app or desktop. Adding a forecast to your planner is simple and we talk through it below.

How to add a forecast to your planner

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From any forecast Tap the Menu button to reveal forecast options.
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Tap the ‘Add to Planner’ menu item.
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Name your forecast and select repeating options. For example you may want to repeat on the same day of the week each week.
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From your dashboard you will now see your ride scheduled in your planner.

Pick a Route

Using the weather to plan your food

How much food do I need on my ride? Best check the weather. Ok, I know what you’re thinking, this is another MWS blog that is trying to make any topic about the weather but hear me out. Imagine for a second you’re doing the Ironman World Championships in Kona (or elsewhere…) where year on year the bike splits for the pro men can vary by up to 15 minutes, a time gap that’s amplified when you’re moving slower. 

We know that nutrition is important for cycling, if you run out of gas and crack 15 minutes from the end of a ride it’s often enough to ruin the ride. Now, imagine you’re doing some kind of ultra endurance event that’s self supported, the amount of food you carry at any one time can make a big difference. There’s a balance between carrying enough to get by but not weighing yourself down. 

In order to pack the right amount of food, you need to know the answer to two questions. How many grams of carbohydrate do I need for an hour? How many hours will I be riding for? In both the forecast and post ride analysis, myWindsock calculates energy expenditure on your ride at various points and the total amount of energy used across the whole ride.

This is where our forecasts can be valuable. Check the weather along the route, decide on your clothing. Check how long your route will take this week, pack the appropriate food. If you want to start forecasting your rides and going out well prepared, check out myWindsock here! 

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!