Offseason training tips

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… 

Work begins in the offseason, physiological, psychological and aerodynamic work can be done in the period where disruption from races is minimal.

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.

Britain’s “Classic” Strava segments

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:

Hardknott Pass 

A screenshot of Hardknott’s Strava segment. No surprises about the KOM and QOM holders.

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.

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.

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…

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…

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.

Does aero matter in CX?

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…

This equation describes the force acting on the rider at this point in time. In words, it’s the riders rolling resistance and weight multiplied together plus the force from the air resistance (which depends on the square of the 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.

This equation shows us how much power a rider needs. This is oversimplified as in a real cyclocross race there are many more resistive forces acting trying to slow us down but it does allow us to do some analysis.

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…

This plot shows us the power needed only to overcome rolling resistance at a range of speeds.
This plot shows us the power needed to overcome air resistance at a range of speeds.
Adding them back up and plotting them together we can see how much closer it looks to the air resistance only plot, this is because as soon as velocity reaches a certain point that term becomes so much larger the rolling resistance term’s contribution looks very small in comparison.

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.

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.

Using myWindsock to plan a ride

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”
Add your route to planner. Hit ok, add to planner, Strava (or GPX upload) and then “Routes”. Once it’s in, set the date and time your ride is planned for.
  • They check our collection of charts and information.
The quick metrics of the weather are available here. Gives you the probability of rain, of course myWindsock is subject to the same uncertainties of every weather forecast but this gives you a picture of what’s coming.
The weather overview plot is what you get when you hit “View how the weather evolves” and can be found in our charts reserved for myWindsock premium members. This is the chart that helps us avoid those random dips in temperature and the heavens opening at the end of a ride.
  • 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.

How the 2023 Men’s National Hill Climb championships was won

The climb is a stepped climb with a steep ramp at the bottom, a flat bit and another at the top. More details on “The Struggle” can be found in our pre race write 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. 

At this point in the race it was neck and neck between our hill climbers. Gabe was still in the mix and I was long gone over 30s back. The interesting thing to note is that Feather started harder than Ed as both riders were capable of going harder than they did.

‘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%.

The interesting thing here is that Feather clearly backed off as they’re essentially no different in time than at the end of the first segment we analysed. To me this says that Feather put more emphasis on riding the steep section harder while Ed Laverack took a smoother approach to that first section. This is in keeping with their characteristics as riders too, as many view Feather as more explosive than Laverack. Gabe and I were truly out of it but he was still doing quite a good showing whereas I had fully parked by this point (despite averaging over 400W for the first 10 minutes – my offseason and breakfast croissants had clearly got to me). 

‘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. 

It’s clear my lack of pacing strategy was causing issues here. I had run out of gas by this point so I think we will ignore Epton from now on. One thing I thought was interesting is how much closer Gabe Dellar was, proportionally speaking, to Feather and Laverack in this sector. I put this down to Feather and Laverack having a pre planned pacing strategy which both seem to have executed relatively precisely. I think Dellar over-paced this section which shows us the difference between a hill climb specialist and a very good racing cyclist.

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.

The main thing of note here is Ed Laverack losing a second to both Andrew Feather and Gabe Dellar. One second on the descent may not seem like a great deal but one second every 45 is worth 16 by the finish and small mistakes like this add up. This shows us the difference between a great ride and a perfect ride for sure. 

Struggle to the line’

This is where the race was primarily won, Feather put 15s into Laverack here (and two minutes into me). His anaerobic capacity is incredible and the race was won on this final ramp. The interesting thing is that if the hill climb was only this last portion of the race, Feather and Laverack would have a similar result. Andrew Feather was a couple of seconds ahead going into this last section but won the race here. 

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.

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.

National Hill Climb Championships 2023

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).

The segment where the action will take place. For a detailed write up on the course this weekend, have a look here.

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.

The Spindata rankings for hill climbers. I haven’t sifted through the start-list in too much depth but many of these riders will be competing for the top 5 slots.

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.

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.

Are marginal gains still a thing?

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. 

How much difference did 1% make in Kona?

A 1% reduction in cda leads to a performance gain of 15s. This doesn’t mean that 2% automatically means 30s (as you go faster, there are diminishing returns in terms of time) but it’s enough to make a measurable difference on race day. With a world class field athletes can’t afford to leave watts on the table – something Lucy was acutely aware of having come 2nd a number of times.

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.

We recently wrote about our trip to the wind tunnel here and it’s a practice extremely common with triathletes and cyclists these days. If you want to be competitive in these sports then aerodynamics is something you have to take seriously.

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

The time in hours drops from over 4.5 to very close to 4. The numbers here are using power numbers regularly seen in Kona and all other conditions kept the same. The accumulation of marginal gains will see the times continue to drop in the next decade too as we aren’t close to the limit of what’s physically possible with aerodynamics on bicycles.

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.

The women’s Ironman World Championships in Kona

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! 

The race begins with a 2.4-mile swim in Kailua-Kona Bay, where participants must contend with ocean swells and currents. Year by year, the conditions can be variable in Kailua Bay and the duration of the swim can vary. 

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. 

Kona bike course, critics have described it as boring and they might have a point. It’s a barely rolling out and back along a motorway. The wind can provide a bit of spice to the race, however.

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. 

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!

Generally speaking, it will be a relatively cool and calm day (by Kona’s standards).

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.

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.

Pacing a climb with varying gradients

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… 

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… 

Yes, we’ve ignored air resistance as this complicates matters. While the physics engine that myWindsock runs on can handle this complication, for now we will make some kind of low speed assumption that allows us to ignore air resistance (though a good rule of thumb is that it becomes more important to think about in hill climbs the faster you go). 

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?

Here we have a plot of the force experienced by a rider due to their weight (with other components of resistance ignored) as the angle of a climb increases. Three system masses are included here to show how these differences are felt on riders with differing masses. The y-axis, labelled “Weight”, shows us the effective weight felt. The angle here goes from zero (completely flat) to 90 degrees (think literal vertical wall). In reality, a 20% gradient is only 11 degrees but the larger angles are shown to emphasise the point. At these lower angles, the proportion of force can be assumed to be linear (at small angles sin(x) is roughly equal to x).

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.

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.

myWindsock in action at the tunnel – turning data collected into actionable information for race day!

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… 

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.

Here we’ve plotted cda against power requirements for a cyclist riding along a flat road with no wind and no corners just to see how cda impacts the amount of power needed to ride at 40kph. We can see that the relationship is linear (as the cda term in the aerodynamic equation has no exponent) – as cda goes up, so does the required power.

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.

How does a wind tunnel work?

Here we have Ben checking out some of the latest measured tunnel data and looking into how it impacts the time that an athlete takes to cover a 90km Half Ironman course.

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. 

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

We ran a poll on Instagram and found that everyone thought the right hand side run was faster than the left. On the left, we have my original bike fit position with a water bladder down the front and on the right, the bladder is still there but with the saddle back, head down and arms out slightly – a position that was a bit slower. 

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.

Over the race course, this change in cda is worth half a kph – a significant saving especially considering that the position is much more comfortable.

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.

This caused a big change in cda – we will go into more depth on the bottle data in a future blog as it’s something many triathletes and time trialists are interested in – but it was around a 6.5% reduction on drag with a bladder compared to baseline.

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.

Sign up to myWindsock today!