It’s fair to say that racing feels somehow in the distant past and a long way away into the future but as we all know, champions are made in the winter. Mywindsock has long been a tool used by champions and many have utilised our platform to achieve their success. Plans are often made long in advance, for example professional cycling teams often have a rough idea of who they’ll send to various races in December such that they can begin preparing them specifically for their role. It should be similar for you, at this point many events are already in the calendar for 2024. Having an idea such as “I am going to target an Ironman in June” or “I’m going to try and set a 10 mile PB in August” is all you need to start thinking about achieving success. 

Success for users of myWindsock, especially those interested in improving their performance who I am primarily speaking to here, breaks down into two sections. Optimising aerodynamics and equipment and training. We will start with training… 

Training Approaches

Traditionally, coaches have had their athletes focus on their “aerobic base” during the offseason then gradually increase their intensity as the season approaches. This works fine for many athletes, but it’s also worth mentioning that there are many ways to skin a cat here and that different approaches work differently. 

Working on weaknesses: This approach is simple, it just deals with setting out a hierarchy of issues holding you back from performing as you’d like to and approaching them one by one. For example, if your one minute power is holding you back in a race he hen perhaps it’s time to work on this first, then move on to other things once your weakness is at a level that no longer inhibits you reaching the performance goals. Working on limiters is a common approach to improving in general. 

Training based on phenotype/muscle fibre typology: This is something popularised relatively recently. I first considered adjusting training prescription on phenotype from Louis Delahaije (coach of many Olympic Champion cyclists and triathletes including Annemiek Van Vleuten) and he essentially breaks it down as “if you are naturally fast you probably need less of this training”. 

 The “Norwegian Method” of lactate threshold training: The Norwegian Triathletes deserve a little more credit here I think, they don’t just train all the time at threshold but the idea here is you control intensity sessions at threshold/LT2/FTP/Critical Power etc – however you want to measure it, then you spend as much time here as you can sustainably manage in a training week. This nudges your threshold up slowly over time. 

We have only spoken about three potential approaches to training here but the reality is there are an infinite number of potential approaches you can take. The approach you choose may depend on your event, for example a ten mile TT takes between 20 and 30 minutes for most time trialists where working on your VO2 max and maximum lactate steady state might be best immediately before your attempt to peak. This means that traditional periodisation would suit you, however if you’re trying to peak for a 100 mile TT or an Ironman, you might wish to do this kind of work in winter. 

We’ve seen many times on myWindsock that even pacing is rarely the fastest way to perform at the best of your ability, even in hill climbs but especially over a hilly time trial. Check out our blog on pacing a hilly time trial here but you should train to allow your physiology to meet the demands of your performance goal which is rarely doing a smooth power for a given duration… 

Aerodynamics and Equipment Optimising

myWindsock can help with pacing, but primarily our function is to calculate how much a change in cda will impact your performance. myWindsock can be used to estimate these changes through our aero testing but we’ve utilised it at the wind tunnel – which you can read about here.

If you, like many time trialists around the UK, repeat your efforts along the same time trial courses around the UK each summer then you can use myWindsock to see how your cda is trending over particular courses. 

In the winter this can also be done, for example if you are able to get out on your TT bike how is your cda trending across particular Strava segments? Personally, I like to head down to Goodwood and do a couple of tempo laps every couple of weeks on the TT bike just so I don’t forget how to ride the thing. This is something that many local racing circuits offer and is a good chance to see what sort of ballpark cda you’ll be working with in upcoming TTs as well as testing the rideability of any winter bike fits you’ve had done.

Winter is a difficult time to aero test outside, wind speeds are higher and this makes testing outside using myWindsock trickier but it’s a great time of year to get used to a testing protocol so that you can take advantage of any still days. 

If you’re looking to maximise your performance on the bike, you can explore our selection of articles on pacing strategies, aero testing and check out all the features in the app.

Cyclists often daydream about conquering impressive mountains, inspired by professionals navigating legendary ascents in major races. Our goal, among many, is to help you explore the world’s iconic cycling segments, find the best day and give you the information you need to snipe the KOM .

Based on thorough research (some Googling and asking around), we present our initial list of four of the UK’s Strava Classic Segments. myWindsock is perfect for segment whacking on Strava! All segments are available to view in the app.

In this context, a classic segment is defined by historical significance. Exploring the study of past events, especially in human affairs, unveils narratives tied to these climbs. Our aim is to traverse routes that have witnessed the achievements of cycling heroes.

Another defining criterion is difficulty. The challenging nature of these segments is embraced by great cyclists who understand the value of enduring hardship. Conquering notoriously tough segments strengthens resilience, providing a sense of triumph upon reaching the summit. We do not include any easy segments here – sorry to the fans of Surrey who were expecting Box Hill to make another undeserved list of climbs or segments in the UK. 

Without further ado, we present the preliminary roster of Strava Classic Segments, each embodying the rich history, challenging difficulty, and picturesque scenery that characterise these iconic cycling challenges:

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Hardknott Pass 

Riders navigate a narrow, single-track road extending from Eskdale in the west to the outskirts of Wrynose Pass in the east, offering an experience of both challenge and scenic views. On the western side, Harter Fell stands tall, accompanied by the remnants of Hardknott Roman Fort at 660 feet (200 meters) above sea level.

The Hardknott Pass, reaching a maximum elevation of 393 meters, leads to a steep descent with a gradient of 30% (1 in 3) into the Duddon Valley. At the eastern end of the pass, you’ll find Cockley Beck farm, built in the 1860s and owned by the National Trust. The route from Hardknott extends eastward, guiding cyclists toward Wrynose Pass and Ambleside.

Recognised as one of the more demanding cycling routes in Britain, Hardknott Pass features a series of challenging hairpin bends, often affecting visibility. The road surface is known for its poor condition. Winter closures are common due to impassable icy conditions. Following the Highway Code, ascending traffic (including cyclists) should given priority.

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The Great Dun Fell 

Great Dun Fell, standing at 848 meters (2,782 ft), is the second-highest peak in England’s Pennines. Positioned two miles (3.2 km) south along the watershed from Cross Fell, its higher neighbor, it, along with Little Dun Fell (reaching 842 m or 2,762 ft), serves as a landmark on the Pennine Way’s ascent from Dufton. Located within the historical county boundaries of Westmorland, it falls within the ceremonial county of Cumbria and the modern unitary authority area of Westmorland & Furness.

The climb itself is a long one gaining over 600 meters of elevation as you ride up. In order to take the KOM a rider must maintain a VAM of over 1600m/hr – this is perhaps slightly more achievable for more riders, at least compared to Feather’s time up Hardknott. EF Education’s Lizzie Banks holds the QOM.

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Bealach Na Ba 

Bealach na Bà is a winding single track road through the mountains of the Applecross peninsula in Wester Ross, Scottish Highlands. The Bealach na Bà is just one feature on this road, being its highest point and site of several corries.
The historic mountain pass was built in 1822 and is engineered similarly to roads through the great mountain passes in the Alps, with very tight hairpin bends that switch back and forth up the hillside and gradients that approach 20%. It has the greatest ascent of any road climb in the United Kingdom, rising from sea level at Applecross to 626 m (2,054 ft) in about 6 km (3.7 mi), and is the third highest road in Scotland. In typical fashion, the segment is longer than the ‘climb’ with a false flat “fake news climb” couple of km at 1-3%.

The name is Scottish Gaelic for “Pass of the Cattle”, as it was historically used as a drovers’ road. The road is so steep, twisty and windy that learner drivers are encouraged not to drive up it. How anyone ever drove cows up here is completely beyond us but we can be sure they didn’t do it as fast as Feather who, once again, seems to have the KOM…

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Buttertubs Pass

The Buttertubs Pass, situated in the Yorkshire Dales, England, is a high road that winds north from Simonstone near Hawes to Thwaite and Muker, passing by 20-meter-deep limestone potholes known as the Buttertubs. Legend has it that farmers, en route to market, would rest there and, during hot weather, lower the butter they had produced into the potholes to keep it cool.

Locally recognised as a challenging climb, the road gained prominence as the second and highest of three categorised climbs in Stage One of the 2014 Tour de France. German cyclist Jens Voigt led the race over the climb, earning the polka dot jersey as the leader of the mountains classification.

I bet you can’t guess who has the KOM…

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myWindsock allows you to check out any Strava segment, just star it and then plan your assault on the segment. Next week we will do a step by step guide on trying to take a Strava segment making use of myWindsock, Strava and a live segment head unit feature all at once.

If you want to get the best out of your segment whacking, sign up to myWindsock here.

It’s cyclocross season. That time of year when we see cross riders grace our screens and the inevitable conversation of why they’re running deep(ish) section wheels, aero helmets and aero socks comes up. The question of “does aerodynamics matter in cyclocross” comes up a lot but the answer is more complicated than you might think. Basically, it’s yes but not at the expense of other things.

Cycling fast is always the same thing, ultimately it comes down to minimising the things slowing you down. The difference between CX and time trialing is there’s a lot more trying to slow you down on a cyclocross course which makes the distribution of speeds experienced in a CX race relatively wide.

A very simple example

Physics becomes extremely complicated any time that something remotely interesting starts to happen – let alone sliding around in mud, jumping over hurdles and all the other things they do so let’s just imagine that (rare) moment in a cyclocross race when they’re moving along a flat section of the course at a constant speed…

We can re-write this in terms of power by doing a little physics and a little bit of algebra which tells us the power needed to ride at a given speed for some rolling resistance, weight, air density and such.

The key thing to look at here are the speed related terms, we have one which is linear (ie, just speed) and another which is speed cubed. This means at high speeds, the term containing speed cubed (without rolling resistance included is much larger. What this means in practice is that air resistance becomes more important the faster we are going. If we split the terms up and plot power needed with speed we can see this…

So far we have used maths to show us something most of us already know. Aerodynamics becomes more important at higher speeds but does this matter in a cross race? Cyclocross average speeds are highly variable and the likelihood is optimal equipment choice will depend quite heavily on the race. myWindsock in this instant is not going to perfectly predict your cyclocross performance. A (reasonable for road racing and time trials) assumption that we make is that rolling resistance stays static but in cyclocross this assumption goes out the window completely. It’s so variable that predicting it would be pointless but that doesn’t make myWindsock useless in this scenario.

Many cyclocross courses are in open fields, which makes our wind forecasting particularly reliable with fewer buildings in the way to mess up predictions. This means you’ll have a windspeed prediction if you can get close to estimating your own average ground speed. This means you can make better wheel selections as well as decide whether or not to wear aero socks – something I recently found was quite controversial at cyclocross.

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myWindsock can be a powerful tool in its own right, especially on the road. It really comes into its own when it’s paired with a good understanding of physics. If you want to have a go at optimising your preparation for your next race, sign up to myWindsock here.

You can tell it’s November, every marketing email in my inbox is telling me to buy this season’s latest raincoat which is finally going to be the one that actually works but then, after 3 hours of a storm following you around you’re wet, the contents of your pockets are wet and your feet are soaked and freezing. Imagine if there was a way of being a little smarter than this though. There are a couple of approaches for this readily available without our help.

The weather radar guy 

I have a couple of mates like this, they have every weather radar app available (except us for some reason) downloaded onto their phone. They have a constant image in their head aggregating the latest satellite imagery and mentally overlaying the route they have planned out trying to figure out how wet they’re going to get, where it might rain and how to avoid it. Sometimes, this person will even look up a wind map on top of this!

The ‘no such thing as bad weather guy’

“There’s no such thing as bad weather, only bad clothing choices”. This is not true. There is such a thing as bad weather and these people are kidding themselves. This person never checks the weather, has a raincoat on every ride and was probably a member of the Scouts. They are often found making smug comments when it does rain unexpectedly as they’re always prepared.

The myWindsock guy

Everyone knows an optimiser. The person that tends to get things right, whenever they plan a route it’s always a tailwind home. They will plan to leave at 3:07pm as the rain stops at 3:06pm and there’s still time for an hour provided the traffic lights are on your side on the way back to town as they will be. You don’t know how they do it, but they seem to get everything right, well let us show you how they’re doing it…

• They sign up to myWindsock.
• They head into myWindsock and hit “add to planner”
  

• They check our collection of charts and information.

• They have a perfect ride – armed with all of this information the optimisers go ahead and ride round dodging rain showers and headwinds like they have a sixth sense.

myWindsock has developed a reputation amongst time trial specialists and triathletes for being a performance aid. This is true, we help people pace and use the weather to get the most out of themselves but winter is where myWindsock truly comes into its own. To keep dry this winter – sign up here.

This past weekend saw Britain’s finest hill climbers congregate in the town of Ambleside to launch themselves up a rather famous climb called “The Struggle”. We wrote a segment analysis here as well as a piece with pacing advice here (which I completely ignored and went out way too hard but that’s a story for another day). 

In the men’s race, the big showdown was between Ed Laverack and Andrew Feather, where Feather came out on top taking 18s on Laverack. Both riders put out amazing performances being well in excess of 7W/kg for the climb. 18s is a bigger margin than people expected from talking to riders and fans on Sunday and, based on how important pacing is on rolling climbs like this, we thought it would be interesting to look into where Feather made the time up on Ed Laverack. 

Where was the time gained?

In order to do this, we will make use of Strava segments. The Struggle has a series of sectors and is a rolling climb (in the sense that there’s a reasonable amount of descending involved along the way) and the segments we will use are ‘3 min’, ‘National HC sector 1- (no flat)’, ‘Struggle… sec2..the kind of flat bit!’, ‘Struggle Climb Descent’ and ‘Struggle To The Line’. Broadly speaking these segments represent the steep start, the flattish rolling bit in the middle, the descent and the final wall.  

We will look at the progress of four riders, Feather, Laverack, Gabe Dellar and me. These represent two great hill climbers, a very powerful cyclist who is not a hill climb specialist and an 80kg triathlete who’s just spent a week off the bike due to the off-season. 

‘3 min’ 

This is the first segment, it’s just shy of 700m long with an average gradient of 12.7% and it gives us a good idea of who started the hardest. 

‘National HC sector 1- (no flat)’

This sector includes the one featured above but extends further to 2.38km with an average gradient of 10.8%.

‘Struggle… sec2..the kind of flat bit!’

This is the most interesting segment to see the time gaps as it will show the differences in pacing strategies being employed. 

‘Struggle Climb Descent’

This segment tells us who’s been doing their research and riding the course first. There was no need to touch the brakes on this descent portion of the course and riders who had done the climb a couple of times would know this.

‘Struggle to the line’

Could Ed Laverack have won and a brief discussion about the model of Critical Power?

The critical power model would have Laverack and Feather with similar CP values and Feather with a larger W’.  

What this essentially means is that both Feather and Laverack have similar aerobic capacity but Feather has a greater access to glycolytic power. The question becomes how does Laverack win on a climb which is essentially made for Feather? The only path I see is for him to pace it harder at the start and descend faster with more focus on aerodynamics for the flat bit. The reality is, given Feather’s physiology, Laverack may have been fighting a losing battle though. 

The critical power model is a valuable tool for assessing sustainable power output, but it has several limitations. One key limitation is that it assumes a linear relationship between power output and duration, which may not accurately represent the nonlinear nature of fatigue. In reality, fatigue can accumulate at different rates depending on various factors such as intensity, environmental conditions, and individual variability. The model also simplifies the complex interplay between aerobic and anaerobic energy systems, making it less precise for athletes with varying strengths in these systems. It’s probably the case that Andrew Feather is such an outlier and the CP model underestimates his ability to produce high powers.

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Next time, we will go through Illi Gardner’s performance that won her the women’s British Hill Climb championships. If you want to plan your next race with the precision of the best riders in the world, head here and sign up to myWindsock.

The Struggle” is the perfect name for the location of this year’s National Hill-Climb Championship. It’s where the best hill climbers from all corners of the country (and also Tom from myWindsock) will gather this Sunday for the final national title race of 2023 in any cycling discipline (we think).

This iconic event unfolds along a challenging 2.67-mile (just over 4km) route in Cumbria. This climb stands out as one of the longer courses for this championship, offering a real test of endurance. The average gradient of the climb is a demanding eight percent, with the steepest part reaching a punishing 24 percent.

The action kicks off just outside the charming town of Ambleside, and the event is masterminded by the Lakes Road Club and Barrow Central Wheelers. For this year’s edition, both the reigning women’s and men’s champions are returning to defend their titles (and Tom from myWindsock will also be trying not to walk up the steep bit).

In the men’s competition, reigning champion Andrew Feather has made a remarkable recovery from an illness he battled in September and is feeling in top form as he approaches Sunday’s climb. He acknowledges that September was a tough month for him, but his power output is back where it should be.

As the event approaches, Feather is making some last-minute adjustments to his bike this week (every gram helps) and has headed up to Cumbria early to prepare. While he’s uncertain about how he will perform on the day, he recognizes that Ed Laverack is likely the favourite, especially given his specialisation in long climbs. Feather has conducted several course reconnaissance rides and feels well-prepared. He’s determined to give it his all and hopes for the best. The uneven gradient may also suit a rider like Feather who’s shown many times before that he has a rarely matched ability to accelerate on steeper gradients. We have showed that pacing steeper sections harder can save a lot of time and this is something Feather has proved excellent at.

Ed Laverack, who many (including us on balance) are tipping as the pre-race favourite, including the national rankings system on Spindata, is eagerly anticipating the challenge.

On the women’s side, Illi Gardner, who rides for Wahoo-Le Col, is back to defend her title. However, she hasn’t had the chance to face her rivals this season, so there’s an air of uncertainty around how the title race will unfold. Gardner acknowledges that while The Struggle’s longer climb plays to her strengths, she’s been working on improving her “punch.” She points out that the National Championship is the first opportunity for competitors scattered across the country to go head to head, making it a bit of an unknown in terms of the competition. Despite the uncertainties, she’s looking forward to the challenge and has been focusing on handling adverse conditions while staying calm and composed. Illi also took the Sa Calobra QOM going under 30 minutes and plenty are saying it’s her race to lose.

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myWindsock will be in attendance on Sunday, while I (Tom) won’t be challenging the scoreboard too much, we are looking forward to a great day and will be covering conditions and results on our Instagram story. If you want to plan your effort perfectly, there’s no better place than myWindsock – check it out here.

Marginal gains in the context of cycling refer to the practice of making small, incremental improvements in various aspects of a cyclist’s performance and equipment to gain a competitive advantage. This concept became particularly popular in professional cycling thanks to Team Sky (now Ineos Grenadiers) and their former performance director, Sir Dave Brailsford. The idea is that by focusing on many small improvements, collectively, they can lead to significant overall performance improvements. Since the Sky glory days, we’ve seen performance improvements across a number of endurance sports including cycling, triathlon and running – a large part of this is the accumulation of marginal gains. 

A few weekends ago we had the Ironman World Championships in Kona, which was won by Lucy Charles-Barclay in no small part due to how aerodynamic she is (as well as obviously being a great swimmer and runner). Some athletes were less dialled than Lucy, however. We saw road helmets, slow chain choices and sleeveless triathlon suits and it dawned on us that Ironman is probably the sport where marginal gains accumulate the most. 

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How much difference did 1% make in Kona?

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Aerodynamic testing is a process that takes place over a number of years and the gains accumulate over time. On average, athletes are more aero than they were ten years ago but the distribution of individual athlete’s aerodynamics is similar now with world class triathletes and time trialists somewhere on the spectrum of just muscling their way to results and being perfectly dialled.

Over the years, the cda of the athletes competing at the pointy end of the race in Kona has dropped. We know this as athletes aren’t actually doing much more, if any, power than they were back in the days of two-piece triathlon suits and those weird triathlon crop tops. We just know now that those (awful) suits also weren’t very fast – among other gains found here and there. We can see how a ‘typical pro’ athlete’s time might drop as their cda goes from 0.3 down to 0.2 on the same day, pushing the same power…

Kona – a generational shift in times

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Accumulating gains – a self fulfilling cycle

The other aspect worth considering here, as we see times tumble from one year to the next (myWindsock successfully predicted a Kona course record was coming) is that as riders go faster, they expend less energy. Energy is the integral of power with respect to time. What that means practically is the way you calculate how much energy has been expended is by figuring out how much power was done for how long and adding all of those bits up to get energy. Given that the amount of energy we have access to is the limiting factor in an Ironman, by reducing the amount of time spent on the bike we have more available energy left to run with. This means that athletes can run faster.

To answer our question posed, yes marginal gains still make a difference. Team Sky popularised the concept and Jumbo took it to the next level but the reality of it is that all of us still have unrealised gains and these can really add up. If you want to see how these look on your local time trial or triathlon bike leg, click here.

We take a detailed look at the weather forecast for Kona 2023!

The Ironman World Championships in Kona, Hawaii, represent a pinnacle in the world of ultra endurance sports, marked by distinct challenges related to wind, aerodynamics, heat, and weather. Kona is no ordinary Ironman and conquering the conditions is as big a part of the ultimate outcome as conquering the race distance. 

Held annually in October, the event draws elite triathletes who have qualified through a series of global races. Kona serves as an unforgiving testing ground due to its challenging natural conditions. This year, Kona is made more special by being the women’s championships – age group and professional women will take on the island alone for the first time! 

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The swimming times for women in the Ironman World Championships in Kona can vary widely. The 2.4-mile (3.86 kilometres) swim portion of the race typically takes competitive participants anywhere from around 50 minutes to 1 hour and 20 minutes. Elite professional female triathletes who compete in Kona can complete the swim in the faster end of this range, often finishing in approximately 50 to 60 minutes. 

Following the swim, competitors run through transition to the bike, covering 112 miles through the island’s somewhat varied terrain. The Queen Ka’ahumanu Highway (Queen-K) exposes cyclists to fierce head and cross winds, significantly impacting their aerodynamics and kit selection. Disc wheels are banned in Kona due to the wind conditions, Ironman clearly not aware that a 90mm front wheel is much twitchier in crosswinds than a disc… 

The 26.2-mile run through lava fields and Kailua-Kona, presents an additional set of challenges. The Big Island’s high temperatures and relentless sun introduce a critical element of heat. Athletes grapple with maintaining hydration and minimising heat-induced fatigue, going too hard on the bike could come back to bite you. The Energy Lab section is notorious for its extreme heat, which has seen the end of many a world title challenge. 

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The weather

We are now on Wednesday at the time of writing and with the race taking place on Saturday we are probably close enough for a decent weather forecast. Let’s take a look at the wind in Kona!

The BBC weather report also looks similarly mild. Generally speaking, real feel possibly won’t even breach 30 degrees which is relatively rate for races in Kona where heat is usually a huge factor. The temperature and humidity combination is still sufficient to induce overheating in an athlete that has not paced well but it should allow a greater degree in the flexibility of pacing strategies – something athletes might need if they wish to follow Taylor Knibb’s pace on the bike.

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Will we see a course record?

All of this points to conditions being relatively fast, and with the best female pro field ever assembled (in my opinion), the racing will be red hot too. The course record sits at 8:26 and was set by Daniella Ryf who is racing on Saturday. Personally, having looked at the data, the field and the weather I think we will see a number of women under 8:30, probably the entire podium at a minimum but there are a number of athletes very closely matched. It doesn’t seem impossible to me based on the wImpact scores on the bike and run that we could see a time under 8:20 win the race – a time that would have beaten Jan Frodeno in 2014!

Partially, this is due to the change in bike tech we’ve seen in the past decade as well as the calendar change leading to lower winds experienced in the past couple of years.

If you want to experience the course preview in a bit more detail – check out myWindsock here to load up your own forecast.

It’s hill climb season and that means our inboxes are full of pacing questions. Most of these questions come from pacing climbs with varying gradients. Everyone knows how to pace a climb that’s a steady gradient – just figure out roughly how hard to go then go that hard. With variations in gradient however, things change. Other forces come into play, many climbs have a flat bit at the bottom and gradually get steeper, others are stepped climbs or may even contain a small descent in the middle. The thing is, with any climb of varying gradient, pacing it evenly is likely not the fastest way to get up it with whatever available energy you have at your disposal. To explain this concept we will jump straight into an example… 

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A climb with an increasing slope… 

Let’s imagine an example where we have a climb with a gradient that increases slowly from flat to completely vertical. At any point on the climb, the forces acting on something ascending this climb (in our case, usually a bike) are… 

The thing for us that’s important is the component of weight acting down the slope – this is the weight that we feel when trying to accelerate the bike up the climb. This component of weight is proportional to the sin of the slope angle. How does the component of weight acting change as that angle increases?

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How should I pace then?

Over any given duration, you’ll have some given energy budget (ie, you know can normalise some power for some duration) and this should be your starting point. From here, it’s about thinking where to invest that energy for the biggest return on speed. Generally speaking, this equates to going harder on steep bits as the resistive forces increase with speed at a slower rate when you’re moving slower (due to the exponents in the aerodynamic equation).

In simple language, practical advice would be to change what you’re thinking about based on speed – for flat parts you’re working against air resistance, for moderate you’re working against both air and gravity and for steep you’re working primarily against gravity. Go harder on steep bits, get more aero on flat bits.

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Thinking about, and quantifying, these things is far from simple and it’s made easier when you have a physics engine to handle the calculations for you meaning you can focus entirely on preparing yourself for race day – knowing that you’ve used all available data to inform a race plan you can be confident in. If that sounds like your sort of thing – sign up to myWindsock today.

Recently, myWindsock went to a wind tunnel and found out some very interesting things.

If you log into myWindsock and open up a forecast, you’ll see a number which is labelled as ‘cda’ – this is your coefficient of drag multiplied by your frontal area. myWindsock, generally speaking, does a pretty good job of estimating your cda from previous rides which you can pop into planned rides to see how fast you might go (when combined with weather forecast data, your weight and other variables). 

Recently, I went into the tunnel and, given that I do quite a bit of work here at myWindsock I thought I’d drop Ben a text letting him know I’d be going and he kindly decided to come down. I was quite pleased about this. Who better to provide their opinion on what to do next than the founder of the most democratic virtual wind tunnel available on the market? 

The reason I went to the tunnel is because I’m currently in the process of trying to get a pro win under my belt in a middle distance triathlon. The thing is, I’m not particularly physically talented (I’m ok for sure but by no means some kind of freak of nature). This means I need to ride faster without simply pumping out 350W for two hours – enter my aerodynamic era. The first step was to go to the tunnel and measure my cda.

The next two sections explain cda then (simply) how a wind tunnel works. If you already know these things or, alternatively, don’t particularly care and just want to see how much speed we found then scroll past these bits… 

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What is cda? 

CDA, or Coefficient of Drag Area, is a critical concept for cyclists, especially those interested in going faster. It’s a measure of how aerodynamic a cyclist and their equipment (known as a ‘system’) are as they move through the air. Generally speaking a good time triallist’s cda will be around (or lower than) 0.2 – though this can take many trips to the wind tunnel and velodrome to achieve. 

Imagine riding a bicycle through the wind. The faster you go, the more the air tries to slow you down.

CDA takes into account two key factors:

1. Coefficient of Drag (Cd):

This part represents how “slippery” you and your equipment are to the air. A lower Cd means you’re more aerodynamic, like a sleek, streamlined shape that doesn’t create much resistance. It also means you’re likely wrapped in some kind of aerodynamic material (like a skinsuit) that manipulates the air in ways that reduce drag.

2. Frontal Area (A):

This is the size of the surface area the air hits as you ride. If you crouch low and make yourself as small as possible on the bike, you reduce your frontal area. It’s a measure of what the air ‘sees’ as it approaches you. 

CDA is calculated by multiplying Cd and A. So, if you have a low Cd (meaning you’re very aerodynamic) and a small A (you make yourself compact), you’ll have a low CDA, which is great because it means less air resistance, and you can ride faster with less power. Cyclists and engineers often use wind tunnels and computer simulations to find ways to lower their CDA. This can involve using more aerodynamic equipment, adjusting riding positions, or choosing clothing that reduces drag. One thing that’s often surprising is that one thing that tests fast on one rider can test slower on another showing the importance of measuring CDA and not just assuming that aerodynamic gains are the same across all systems. 

In competitive cycling, especially time trials and triathlons, having a low CDA is crucial because it can make the difference between winning and losing. Riders strive to strike the right balance between power output and aerodynamics to maximise their speed and efficiency on the bike.

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How does a wind tunnel work?

A wind tunnel is a clever machine used to test how things, like aeroplanes, cars, or even buildings, respond to moving air. It can also be used as a means of making various objects and people more efficient (think F1 cars and cyclists). Imagine a wind tunnel as a giant tube, kind of like a long, narrow room with powerful fans at one end.

Here’s how the process of measuring in a tunnel works:

1. The Model:

First, scientists or engineers create a small-scale model of the thing they want to test. It could be a miniature aeroplane or a tiny car, for example. Alternatively, the tunnel is big enough (as the one we visited was) to fit a 1:1 size model in there (such as a fully grown cyclist and his bike). 

2. The Tunnel:

They place this model inside the wind tunnel, usually near the fan end. The tunnel is designed to be smooth and sleek inside to make the air flow nicely. This means the only disruption to the flow is caused by the subject of the test.

3. Air Flow: 

Now, here comes the exciting part. The fans at one end of the tunnel start blowing air super-fast (or not, depending on what you’re testing) down the tube. This air simulates the wind that the real thing would experience when it moves.

4. Testing: 

As the air rushes over the model, sensors and cameras record all sorts of data. They measure how much force the air exerts on the model, how the air pressure changes, and even how the air flows around it. In the specific case of a cyclist, there are cameras to ensure the same position is being held by the rider to ensure changes made are isolated and any differences in measured CDA are due to the target change and not some accidental positional change. 

5. Analysis: 

Scientists (or Tom, Ben and Andy) analyse this data to understand how the real thing would behave in different wind conditions. They can tweak the model or make changes to improve its performance or safety. This is where myWindsock came into its own for our analysis – as a means of putting the cda number into context we plugged the measured value from the tunnel into a myWindsock forecast of the target event to see how the changes in cda impact the overall time of my target race with the pacing plan input into the forecast. 

6. Repeat: 

The test can be run many times, changing the wind speed or direction to see how the model responds in different scenarios.

In the end, a wind tunnel helps engineers make sure that aeroplanes fly smoothly, cars are fuel-efficient, and average triathletes can cycle fast. It’s a real aero-nerd’s science playground where we can learn how things interact with the air. 

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What did we learn in the Wind Tunnel?

The first thing that we learned was that speed matters. What’s fastest at 35 kph isn’t necessarily fastest at 45 kph. This is particularly important for my case as I’m racing a triathlon where the speeds are slightly slower for a couple of reasons – the primary one being that the finish line is not where the bike course ends… We had a couple of runs and suspicions of things that have tested faster at higher speeds but at “triathlon speeds” were actually slower.

What looks aero isn’t always aero

Other than the fact that the left hand side position was faster, it was also more sustainable (for now, though these things are trainable). The run on the left had a cda (at 40kph) of 0.239, the run on the right had a cda of 0.249.

We can see how much of a difference this makes, over 90s for the same power during the course. This can be combined with the fact that the position on the left hand side is easier to run off as well, being less muscularly strenuous. 

Stuffing your drink down your top can make you faster 

Anyone who’s done a triathlon will know of the difficulty that various hydration systems can come with. Bottles mounted behind the saddle are prone to launching themselves out of their cages with the slightest bump. Recently, it’s become fashionable to shove a Camelbak water bladder down the front of your suit – primarily for aerodynamic reasons but it’s also quite a convenient place to keep your nutrition.

Knowing your cda can help you plan

Relatively small changes in cda over long distances can be worth minutes. When you add these time changes up it can change the amount of sustainable power as well as nutritional planning. The reality is, combining aero data that’s been measured with the processing power of myWindsock is a valuable tool for any athlete and there’s no doubt that all the top contenders are doing this.

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