How much slower is +5Kg (11 lbs)

Due to a very serious spinal injury, myWindsock founder Ben, had 12 months without cycling. He returns to cycling 5Kg (11 lbs) heavier. How much slower can he expect to be? See the Instagram post below.

A bit more detail

We are all about real world riding, so we picked a very typical 25 mile course, on an average UK spring day. This course has some small ups and downs but would be categorised as flat. You can try the course yourself here, J4/8.

Our experiment was acrross 3 power ranges, 100, 200 and 300 Watts. Look at the chart below to see the differences between the powers. The differences are considerable. Remember, the time affect of a resistance compounds the slower you are moving. Less power, greater cost. No more, “I’m too slow for that upgrade” 😉

Often cyclists are surprised by how little time weight costs on a flat course. We are told lighter is always better and to upgrade to the lightest components. As you can see losing weight will have an affect on your speed, but we hope this will keep everything in perspective when making lifestyle and financial choices.

How to try your own experiments

The beauty of myWindsock is that all the variables are accounted for, Physics, Weather & Performance. This allows you to get real world test results in a virtual environment.

  1. Simply pick any route from your “Activities & Routes” menu.
  2. Set the date and time of your experiment for the most accurate cycling weather.
  3. Make changes to your Virtual Athlete profile.

Have a try yourself here.

Preparing for my time trial

Hello readers of the myWindsock blog, lately you’ll have noticed we’ve been a little quiet here. This is because we have been working on partner content with CTT and NoPinz but we are back today and I (Tom) have signed up for a TT this coming weekend! I thought it might be a good opportunity to do a mini series on how I will use myWindsock to get ready for this TT, predict my performance and plan my ride. 

The race is a road bike time trial – this means I’ll not be allowed a TT specific bike or helmet – as well as restrictions on the kind of wheels I can use. It’s a 15 mile time trial on the H15/10 near Maidenhead. 

Luckily, I’ve done a few road bike time trials so I have plenty of previous data to help me prepare.

Predicting the race duration

The first step is to figure out roughly how long the race is going to take me. For this, I’ll need a cda value to plug into myWindsock. Using a time trial I did in August last year on my road bike I can get a value for my cda which will be relatively accurate. The stats from the race are below…

I didn’t have a great day averaging a lower power than I wanted, but the race has come in handy as I can use it to hopefully have a better day in future! A good example of why getting out to race is rarely a bad shout! From this race we can use my live cda plot to predict performance at another TT.

This plot shows us how cda develops with time and generally there’s a couple of key takeaways from it… 

  1. My cda on descents doesn’t vary a huge amount, but does get slightly lower as I go down hill. 
  2. I sit up way too much on faster climbs – this is something to avoid in my coming race. 
  3. My flat cda is around .253, descent cda around .247 and climb cda around .270.

The second step is to figure out how much power I can do at my race. The previous race we used to calculate my cda wasn’t representative of my abilities at the moment but recently I’ve done a critical power test. The outcome of this test put my critical power at 360W bang on – this is the power I’ll aim to average during the course of my TT at first and make micro-adjustments based on predicted race duration.

Plugging these numbers gives me a time of 34:39, or a speed of 43.2km/h… Stay tuned for tomorrow’s blog on my power plan, with a weather impact of 4.5% predicted, he who rides the smartest in the wind will prevail! 

How will a ride feel?

Take a look at the below graphic for this week’s Manchester District 10 mile. If you subscribe to myWindsock Strava Activity emails you may have already seen a similar graphic for your own rides. If not, activate your emails here.

56.4% headwind isn’t good news! However it is only through viewing the Feels Like Elevation graph beneath that we begin to see what affect the wind will have on the course.

Relating the wind to it’s equivalent elevation gain is one of the ways we are helping to describe the weather for cyclists. Learn more about Feels Like Elevation.

So what does this tell us? Initially we see an easing of the course profile due to the tailwind start. Then, once the headwind begins, the road begins to feel harder than the traditional elevation profile would suggest.

Graphs like Feels Like Elevation can be found for any past activity and any future ride forecast. Simply select the route from you Activities & Routes menu to begin.

If you haven’t already signed up for myWindsock Weather & Analysis, start here.

How much time does a skinsuit save?

If you’re reading the myWindsock blog, or came across this from our friends over at NoPinz it’s likely you already know what a skinsuit is and you might even be sold on the virtues of their number pocket that saves you watts. If you attend a local time trial, it’s likely the pointy end of the field will be in a skinsuit and these days, most people wear one for all forms of racing. The uninitiated, or even those of you that only take part in the skinsuit wearing because everyone else does, might be left wondering why people wear these? Surely a jersey and shorts is more comfortable? It certainly makes using the bathroom a little easier. We know a skinsuit is faster, but how much difference will it really make on race day? 

With great partners like NoPinz, we are able to get a hold of some data that tells us how many watts a skinsuit saves a rider and this can be converted into a change in cda. That’s all fine and good – but still doesn’t mean much on race day. What we really want to know is how much time will this save us today, or on the day of our race? During his hour record attempt, GCN’s Ollie Bridgewood used a NoPinz skinsuit to save himself a whopping 20W. These numbers are seen across the board and a ten percent reduction in drag due to a well fitted skinsuit is commonly seen.

Here at myWindsock, we specialize in turning data into information giving you confidence on race morning. Cycling is an uncertain sport and anything that can reduce the noise in the information that drives your decision making is valuable. By making use of our physics engine, we can calculate how much time a skinsuit will save you on a particular course.

A worked example – the Perfs TT

For our simulation, we will use two runs of myWindsock on Sunday’s open time trial which is being held on the Portsdown Hill circuit. We have fixed the cda at 0.220 for the first run and, while keeping all other variables fixed, we will reduce the cda to 0.198 for the second run. This is roughly the proportion of savings a skinsuit will achieve – worth around the 20W that Ollie was able to save with his Flow skinsuit from NoPinz. For this, our test rider is pretty handy – being able to maintain 325W for the duration of the TT with a system weight (bike, rider and equipment) of 80kg.

Test run 1: cda = 0.220

Our rider is coming in at a shade under 39 minutes with an average speed of 41.1kph – not bad! Let’s improve his wardrobe choice slightly and pop him in a NoPinz skinsuit and drop that cda.

Test run 2: cda = 0.198

The savings are huge, more than a minute! This is just the skinsuit too, imagine the cumulative savings from pacing, optimised position and other equipment choices. Slower riders will also achieve greater time savings for the same proportional saving in aerodynamics. As we can see, a skinsuit is worth it.

If you want to see how the watt savings touted by brands turn into time savings on your local TT course, they’re all available in myWindsock pre-loaded. Just hit Activities & Routes, UK Time Trials, and then scroll until you find your open TT! Or simply go here UK Open & Club Time Trials. On top of this, you’ll be able to see what kind of power is required for whatever performance level you are targeting.

How much slower are Winter Time Trials?

To mark the first British Open time trial of the 2023 season, we were happy to help Cycling Time Trials, the British governing body for time trials, with a bit of data.

> Read the Cycling Time Trials article

> BS19 Ely & District myWindsock Forecast

What is the difference between Winter and Summer?

To find out the difference between Winter and Summer, we ran a simulation for every day of 2022. That’s 365 times around the Ely & District course! We ran the myWindsock simulations at 300 Watts, 80kg, 0.200 CdA. Here’s what we found.

Each orange dot is a simulated time based on weather conditions. Each day of 2022 represented.

You can see from the above graph the day to day the variability of times for the BS19 course due to the weather. Time range from 55 minutes in Winter Months to 53 minutes in the Summer.

Another thing to note is the seasonal day to day variability, that is the difference between two days of the same week or month. In the Winter we can see this is around 60 seconds, however times are a little more consistent in the Summer at around 30 seconds. Good job myWindsock give’s you the tools to measure the impact of the Weather.

> Find your Open and Club Time Weather and Analysis

We have more information about how weather impacts cycling speeds, here are some more articles.

Why do you ride slower in Winter: GCN Tech Show

Slow vs Fast Riders who suffers more in Winter Kit

Why do you ride faster when it’s warmer?

Why you are slow this Winter

Pidcock’s Sa Calobra KOM Analysis

Last month we did a bit of Sa Calobra analysis for the GCN Tech Show. So when we saw the KOM time tumble, we had to do some analysis!

Surprisingly, it wasn’t a gift day. In fact it was around 1 second slower than Ed Laverack’s KOM day! We’ll call that one even. Air Speed is the speed of the airflow around the rider. We’ve shown the speed difference from ground speed here.

Overall power was 8 Watts higher, giving Tom a 24 second advatange. That’s a huge 6.6Watts/kg!

Next an assumption on System Weight. That is the weight of rider, bike and kit. Rider stats show Tom as 1 kg lighter. This finds Tom another 15 seconds.

Now the big one, Aero! Tom finds a massive 72 seconds. Reducing air resistance from 14.3% down to 10%. The aero Tom has here, is the equivalent to a very well tuned Time Trial Bike position. So we’d assume some assistance here.

How fast would your Sa Calobra time be?

You can find your own time on Sa Calobra, simply by loading the myWindsock forecast. Check out the Sa Calobra Strava Segment

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.

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!