Le basi di Aerotest

Sebastian: So, second part, no — first real podcast this time. After we gave each other a round of applause in the first episode, today we want to actually explain what Afasteryou is and what the platform can do. We'll start with the Aerotest. And I'll pass the ball right over to Sebastian, who obviously knows this inside out. So what actually is an Aerotest?

Björn: An Aerotest is both a calculation and a test protocol that I can run to measure my own aerodynamics. And with that, welcome back, Björn. Happy to be here again. And maybe today we'll actually cover some real content, like you said. And we have a platform — afasteryou.com. You can go there, register, and have a look. The Aerotest is in there. Our Powertest is in there. There are descriptions. There are videos and instructions. But I think... It just makes sense to roughly explain what the Aerotest is and how you use it. The analysis for the Aerotest is done through the platform, but the execution is of course a protocol I have to run myself. So what is aerodynamics? What is it, really? Ultimately, when we're out riding the bike, two factors essentially determine how fast you ride. First factor: how much power can you put down on the pedals — your oomph, obviously. Every cyclist would say by default that you should spend your time training. But there's a really decisive second factor — because we don't all ride infinitely fast — and that's wind resistance. Now, for mountain bikers and those who ride a lot of elevation, you also have to overcome the gradient force — basically riding up the mountain. Then of course watts per kilogram is what matters most. But if we're in triathlon, or just as much in road cycling, then a big portion where we ride flat or downhill — that's where wind resistance is decisive. And in the Ironman and triathlon world, most courses are flat, and aerodynamics is really an essential factor. Rule of thumb: either you improve your power by 10% or you improve your aerodynamics by 10% — and that's roughly the same effect. It's not far apart at all. And Björn, you'll know this too — it takes a while to gain 10% in power.

Sebastian: We tested especially with road bikes on some Conti riders, seeing how much speed could increase at the same power. And when we extrapolated, we quickly saw we'd theoretically have 20 watts threshold gain. But we just improved the aerodynamics, the position on the road bike. And I mean, 20 watts improvement would have been a lot, lot of work in that case. So those are low-hanging fruits. I think this phrase is going to get used a lot.

Björn: It's also something I've observed again and again. We've done many aero tests outdoors. And when athletes are outside and you improve their aerodynamics, it's not something you necessarily notice yourself. Because that subjective feeling of how fast you're going outside — that's mainly defined by how hard you're pushing yourself. Not necessarily by how fast you're actually going. Whether I'm riding 40 or 42 km/h, I don't necessarily notice. But the difference of 2 km/h is sensational. And when someone does an aero test with us outside and realizes: at the beginning they were riding 35 or 36 km/h at the power they chose for their race. And then toward the end of the test, when we've been able to implement improvements and they're suddenly riding 38 or 39 km/h — which isn't rare — they suddenly realize, wow, something's happening here. That's of course not the high-end measure of saying, okay, now my speed has improved, because there are tons of parameters tied to that. But fundamentally it's already a perception, and they pick up on it really quickly. So the Aerotest is a procedure to measure aerodynamics. Traditionally you know the wind tunnel for this, or the velodrome. What Afasteryou has developed with the Aerotest is a field test that I can run outdoors myself to measure this aerodynamics — and most importantly, to improve my aerodynamics. And this is actually the same for all methods out there. Wind tunnel or velodrome — most methods are based on trial and error. Sure, you have an idea of what might be aerodynamic, but ultimately I have to change one thing at a time, test it, see if I improve, and then test further. There are more modern methods — CFD analyses, computer methods — that could do investigations, but those are still in their infancy. So classical aerodynamic improvement still works the same everywhere: test, test, test. And that makes the big difference. And we've already answered part of what the Aerotest delivers: a significant speed increase. Which is equivalent to a major improvement in threshold power.

Sebastian: And that's something really great. I had a nice conversation yesterday with a good coach who said: he doesn't care about power numbers at all. It's about the athletes getting faster. We need speed. And we sometimes confuse speed with power. We should — you can't just swap the shoes however you want. At the end of the day, it's about who's faster. I always remember a nice anecdote I have with a friend of mine. I positioned myself a bit more aerodynamically on my road bike, and we rode next to each other, base pace, a bit brisker, around 35. And he suddenly had to push 35 more watts — funny coincidence — and I was just cruising comfortably next to him. That effect was massive. Sure, he sits up like a wardrobe, but he could push significantly more power than me. But at the end of the day, he wasn't faster. And that's what you should always remember. It's always about how many km/h we're capable of riding, not how many watts.

Björn: Exactly. I mean, the wattage is nice. When you have that kind of power, you know, okay, normally I should be fast. But then the question often comes: why are the others so much faster, even though they're pushing 30 or 40 watts less than me? And that's where aerodynamics comes in. And we actually have most of our clients coming to us via this route — they have really good power numbers and then wonder why they're not fast. And then they come to us and ask themselves: why could I not be faster? But there are plenty of others out there who could benefit just as much, who maybe don't compare themselves with others through power numbers — how many watts this person puts down, how many watts that person puts down — but have enormous potential in terms of aerodynamics. And I think we're especially addressing triathletes here, because... If they say, power values — I just want to finish, and that's what matters. But if you tell them: hey, you could be riding half an hour faster on the bike at the same power if you seriously worked on your aerodynamics — they'd have a real benefit. Because you don't have to sit on the bike so long, you switch to the run much earlier, you save energy for the run. And there's so much potential still out there that simply isn't being tapped, because maybe aerodynamics is a bit too complicated at first, and you can't just pick it up easily. It's not like planking — I'll just do a plank and somehow get better. You have to engage with it a bit: aerodynamics, how can I test this myself, and then actually get going.

Sebastian: I always have it in my head — when we go back to: who benefits from aerodynamics, who benefits from an aero test? We've got triathletes, and as you mentioned, I can be faster off the bike, use less energy, and have it available for the run. I think that's a really interesting aspect. You don't necessarily have to push more watts to be faster, because then you'd have to burn that energy. What we're currently seeing on our platform is that people are trying to hit the same power numbers but get faster, so they can maximally focus on the run. And on the bike it's simple. Where can I save? What position can I take when I'm pulling at the front, for example? What's the ideal position? Not just on the road bike — even on the mountain bike, there are plenty of races. I'm thinking of the Cape Epic, where we're on long straight sections at 40+ km/h. How do I sit on the bike there? Ideally I have an aero helmet on. Even that can make sense — a more aerodynamic road helmet, for example. And in a seven-day race, the less energy I'm hemorrhaging at the same speed accumulates, and at the end of the day, after five or six days of stage racing, I might be the faster one.

Björn: Yeah, how many kilocalories you can save. Ultimately the energy you're donating to the wind — you get nothing from that. And I think that experience is a bit lacking. A simple example: look, when you're on the road bike, drop position versus upright on the hoods — you already see how big the speed difference is. And you can imagine that's roughly the same difference when you really engage with your aerodynamics. You can get that much out again. And that's what makes it really interesting. So the earlier you start, the better. Because ultimately it's a journey. You can generally say you get more out of one day of aero testing than out of a year of training. Nevertheless, that's usually tied to having a pro with you who can really help. Going out alone on your first aero test and being fully functional, knowing exactly what to do and testing everything — that's rather unlikely. If you have a pro — and we have many bike fitters and aero fitters on our platform who offer this — you can of course get a lot out of one day. But long-term success, from my perspective, comes more from engaging with the topic yourself and testing your own aerodynamics. Then you can also ensure that you always have consistent performance. Nothing is sadder than having an athlete who's super optimized aerodynamically on their bike, then buys a new bike because they think they'll be significantly faster on it, and then the exact opposite happens. They've actually gotten slower. Because the time you invest into an aerodynamic seating position on a bike — that's very valuable time. And you don't necessarily get that back just because you have a new bike. The only reason I'd say a new bike is really worth it — aside from if yours is broken — would be if I can position myself more aerodynamically as a person, as an athlete, on the bike. Because fundamentally, wind resistance is created by the person. 80 percent of wind resistance is the athlete on the bike. And if a new bike allows me to sit significantly more aerodynamically — because my old frame was too short and I could never really stretch out, for example — then that kind of thing makes sense. And then you build a lot more contact with your bike. You build a closer relationship, I'd almost say, in the context of this aerodynamic testing, and then long-term you really have a good position and succeed with it. So that's a great thing.

Sebastian: Now the question obviously is — we know you can do aero tests on the velodrome, you mentioned that, we go into the wind tunnel, it all sounds complicated, we take it to the road with Afasteryou — but it's not that simple. What do we need to get started?

Björn: Exactly. So there's one absolute prerequisite: the power meter. Without a power meter, we can't do aero tests. And that also shows how important this power meter is. It measures power, which gives us the ability to calculate efficiency and specifically aerodynamics while cycling. We have a test where you ride out and back, and data is recorded. We need the power meter to record power data. But we also need a device that records it. That could be a Garmin device, a Wahoo device, a Sigma device, an SRM device. So various GPS devices work, but we need the GPS signal to record the data. One advantage with Garmin, for example, is that we also have an app. You can install it on your Garmin via the Connect IQ Shop. The app is called Aero App. I can install that and then I have complete guiding on the Garmin device. It tells you exactly — if a course is set up, or you can create a new course — how many meters you have to the start, how to ride. You get beeps, and at the end of the test the CdA is displayed right away. I'll also explain exactly how the Aerotest works in a moment. In terms of equipment, basically: power meter and a GPS device. Optimally a Garmin device, because we have this app that's a significant improvement for testing. And so you can generate very precise values — and this is often the wish, to really measure accurately — you also want a speed sensor. And not one of those hub-mounted speed sensors, but a classic speed sensor with a spoke magnet mounted on the fork, like we know from the old days. Why? Because the GPS signal isn't nearly as accurate in measuring speed. GPS accuracy is maybe within 5 or 10 meters. When you're moving, it gets even more pronounced. With modern mathematical filters you can calculate that better. But honestly, a speed sensor where we enter the circumference of our wheel and measure the rotations — there's practically no measurement error. Sure, there's quantization because you only measure whole wheel rotations, but compared to GPS it's super minimal measurement error, and it really significantly improves our calculation possibilities. We have a statistic on our platform: when you test without a speed sensor, the measurement error is on average twice as high. Instead of 2% measurement accuracy, you'd have something like 4% accuracy. And that's a huge difference. So at 300 watts, you're not talking plus-minus 6 watts, you're talking plus-minus 12 watts. And then you have to wonder if you can even measure what you want to measure.

Sebastian: Yeah, okay. What's next?

Björn: So basically the next step — how can I get started? I'd go to the afasteryou.com website, register, look at the Aerotest description, for example. There are documents you can download to prepare yourself. You can check off each item individually — do I have my power meter, do I have the speed sensor, do I have all my materials. It's all in there. You can get some info there. We also have a video on how the Aerotest works. And once you've registered, you also have a link to the Aero App — if you want to install it on your Garmin. Then from my perspective, ideally: I register, install the Aero App, and then I can first go out without a speed sensor on a training ride and just do an Aerotest somewhere. And the cool thing is — the Aerotest is free. We have a free version. You can just do the Aerotest. You don't have to pay anything for it. You go out, just do an Aerotest somewhere. And the important thing is — and this is really a crucial step — it's not about testing everything high-end and super perfectly, it's about getting to know the testing system. What is it like, how do I run the test? Because the test is fundamentally not complicated at all. Do I have the app? Then I have to — the first time I set up a test course — press the start button at the position where the test should begin. And then the app shows you your power, the remaining distance you still have to ride — typically 1,000 meters. You ride that out. In those 1,000 meters you try to maintain a constant seating position. You ride at a constant power as much as possible. And just ride it out. So after 1,000 meters the device beeps once, tells you to coast 200 meters. After 200 meters it beeps again, tells you to turn around. Then it tells you to accelerate — try to get back up to a similar speed. And when you've reached the endpoint of the outbound leg again, the system beeps again and you ride the 1,000 meters back. When the 1,000 meters are done, the device beeps again and the data is sent via your mobile phone to the platform. The platform does the real-time analysis, the data comes back, and you see your CdA value. Maybe you can't do much with that at that point, but fundamentally you've already learned something about aerodynamic testing. You've gathered your first experiences with the measurement system and know the basic process. What I really can't recommend is going out and believing you can do high-end testing right away, bringing everything. Because you'll definitely forget something. A bit of practice, getting to know the system, how does the Garmin display it, what small problems are there. That's probably the best entry point. If you install this Aero App, you should already have done that beforehand. Because with Garmin, installing apps isn't necessarily super easy. But this Aero App — basic installation via the Connect IQ Shop, then it's installed. When you start the app, you'll also have to log into our platform via the app, otherwise the app doesn't know which account on our platform the data should be sent to. So then you log into our platform on the Garmin device via your phone. And you see a pitfall there, in quotes. You need your phone with you. So you always have to check the network coverage. Sometimes you have great test routes and want to test there. You could do this offline testing, but it's significantly more comfortable to see these live results. So I'd always recommend looking for a different test course instead. But okay, jumping ahead — we've now done our first Aerotest. And you've already cleared the first hurdle of how Aerotesting should work.

Sebastian: I think when you do the first test, there are some little things — if you internalize them right away, it'll be a lot better. Namely: constant power, I think everyone can remember that. But above all, a constant speed should also be ridden. So the end speed you want to ride on this course should match the power you approach with. Otherwise — we don't want acceleration in this test. That's an insight that sometimes takes a bit to sink in. But if you have it in your head from the start, that you say, okay, once the 1,000-meter test stretch begins and I've accelerated, the acceleration is behind me. I have target speed, I have target watts, I ride through — then we get significantly more valid results.

Björn: Exactly, so we're already at our second test ride, where we try to optimize things. And high initial speed is important because if you start at a very low speed, a lot of your energy is converted to kinetic energy — motion energy — and not used to overcome wind resistance. And that hurts measurement quality. So my real recommendation: start at nearly target speed. If there's 1, 2, 3 km/h difference, that's fine. But if there's 10 km/h difference, that's a real issue. Then you can say a lot of energy went into this kinetic energy and wasn't available for measurement accuracy. Exactly, and then you can really continue and try to improve measurement accuracy. That's a path. One question: how can I measure very accurately so I can perceive and improve small differences? The other question — which is just as important — is: what do I do with it? Okay, I can now measure my aerodynamics. What now? What should I do? And that's where the question starts: how do I use this system to really get faster? A good foundation is of course having measurement accuracy that allows you to measure things. So... We'd now — as you said — have an improved test because I'm following the test protocol better. I have the speed sensor installed. Optimally I have a dual-sided power meter, ideally crank-based, because those measure a bit more accurately than other systems. Single-sided power meters should really be treated with caution. You can't necessarily say they work great for the Aerotest. You have to differentiate that, because if I'm training and doing a 90-minute session, I've collected lots of measurement data. An error averages out over that long period. Not just a little — it averages out completely over that long period. Whereas when I do an Aerotest where I've maybe only ridden one and a half minutes on one leg, these errors don't all average out. And that's why a dual-sided power meter would be super. But you can also start with a single-sided power meter. It all depends on what CdA shows up on your device. If you're a time trialist and 30 aero points show on your device, you have really big potential to get faster. But really big potential. So you can say, as a benchmark for good aerodynamics on a time trial bike, it's around 22, 21 aero points. These aero points are the measure of how aerodynamic you are, and the smaller the number, the more aerodynamic you are. And the crème de la crème, the best of the best, have under 20 aero points. That depends a bit on your body size too. If you're a 2-meter giant, it won't be that easy to get under 20 aero points. But if you're more of a small, slim lady, it's quite realistic to also get under 20 aero points. And the pros are all in that range. And that's — it's one of the huge differences. You saw it with Jan Frodeno, his new time, world best — under four hours on the bike. Those are aerodynamic aspects, why these cyclists are now so much faster. And it's not because they all have sensationally more power. If we look at the run splits — Mark Allen was the best for a long, long time. Not much has changed there. But especially on the bike, enormous changes have happened. That's aerodynamics, and everyone can benefit from it. So as I said, you look at your device — 30 aero points. If you did this test on the time trial bike, you have massive potential.

Sebastian: What does 30 aero points mean, and if I go down — I lose 5 aero points down to 25. How much faster do I get? Can you quantify that?

Björn: Yeah, it varies. Depends on the distance. Let's briefly talk about long-distance athletes. You can say 1 aero point is roughly 10 watts. So 5 aero points is 50 watts. That won't be exactly accurate later. The bigger these differences get, the smaller the benefits become. But as a rule of thumb, that's about right. And you have to say, if you're a faster athlete who rides significantly over 40 km/h — toward the pro range — then you gain even more watts. If you're a weaker athlete and don't ride as fast — more like 5 hours, or let's say 6 hours — then one aero point is only worth 5 watts. You might say, hey, that's not that much. But keep in mind — you're not riding that many watts either at that point — and then 5 watts can be enormously significant. So per aero point. If I then ride 25 watts more — and if I'm only riding 150 watts on a long distance, then 25 watts is really a lot. That's already over 16%, which is huge power increases. There's a lot in there. And the great thing is — via the platform, you have the option to look at the rankings, to see what CdA values the athletes actually have. And we also have a feed where you can see what CdA values people have when testing outside. And we also have a prediction software on our platform where you can see the differences — what effect does one aero point better have? And you can quickly see where you stand. I think that's a great entry point. First, as I said — ride on the road bike, take the CdA value, get to know the system. Then next time go out, maybe take the time trial bike, or if it's the road bike, test better the second time, factor in the aspects you mentioned. Then really look at the CdA value: where am I, how much potential do I still have? And when I see there's really a lot in there — great. I have so much potential for improvement, how much time I can gain. And honestly, it's fun. Fun when you see how easily you can get faster.

Sebastian: You already mentioned that the body makes up 80 percent. Everyone's always talking about equipment. Our statement is actually: find the right position. Not just on the triathlon bike, but also on the road bike.

Björn: Yeah, absolutely right. Initially, aero testing is obviously easy — you say, okay, I want to test equipment. And there are athletes who say, okay, now I really want to see — do calves work, does the other helmet work? With helmets, the probability is high that it'll make a difference. Measuring calves isn't so easy. You need high measurement accuracy. You really have to make sure you've trained yourself well and have good measurement systems. With helmets, there are really big differences — can be two aero points. So 20 watts. For a really fast rider, it can be almost 30 watts. If you have a fast guy — like we had at King of the Lake at nearly 50 km/h — 2 aero points can quickly be 30 watts. And that makes a big difference. You can test things like one-piece suits, wheels — you have to be a bit careful to only swap one wheel at a time, not both, because one could make you faster and the other could make you slower. Then you don't know what happened. So it makes sense to only test front wheels first. Put the speed sensor on the back, then I test all the front wheels. Good option, if I have some friends, guys I train with, we can also swap equipment among each other. Just swap all the helmets in the group. Can't get much easier than that. Maybe you're sensationally two aero points different just by riding a different helmet. That's the easy entry point. But it's absolutely right to then improve positions.

Sebastian: Speaking of measurement accuracy — every once in a while we see tests, often in magazines, where they test helmets and there are differences of 3 watts. Is that actually measurable in reality?

Björn: Yeah, it's measurable, but that's wind tunnel measurement accuracy. Honestly, with our measurement system, you have to be crème de la crème, and you'd have to have tested the difference more than once. You have a way to get there. But if you go to a wind tunnel and determine these three watts — that's a static measurement setup where I take a dummy, put a helmet on it so the dummy is always in the same position, and then I measure the helmet in that one position. That's also an objective comparison. But the question is always: does anyone ride like that outside? Nobody. Nobody holds their head that still. And that's why — if you really want to measure very small differences, it makes total sense to optimize a helmet for one seating position and bring it into exactly the same position in the wind tunnel to measure CdA. Or tiny details you've changed on the frame. And really objectively, without seating position noise — which causes error — to measure cleanly. But if you really want to optimize your own seating position, it makes sense to do it outdoors, because we move. The bike isn't locked into the wind tunnel — it moves, I move, I move my head up and down. And above all — this is also a difference to the velodrome, where I can really look down, ride my line the whole time. When I'm riding outside with other traffic around, I look differently and I move outside. Now you might say, how can you measure a difference that precisely when I'm moving so much? That's not reproducible. Yes, it's actually quite reproducible. If I repeat this test multiple times with the helmet, I see an average value, and that's the value I ride at on average outside. And I can compare that to another helmet. And that's significantly closer to reality than... generating a static setup of my head that I only hold in the lab, which has nothing to do with outside reality.

Sebastian: So that means aerodynamics is very, very individual. If I move a lot, a helmet tested in a lab might not be for me at all, because if it's super long and I always tilt my head down, then the fin is sticking into the wind. So per se, you can say a fast-tested helmet in the wind tunnel isn't necessarily the fastest overall.

Björn: You could give probabilities. The probability is there that such a helmet will also tend to be better for you. But in doubt — for all the athletes we test with, and especially those who've tested more often — we have to test. Everything else is a lucky draw. Whether you'll be faster with it or not — who knows? And comparing yourself on photos — that doesn't reflect the flow situation on the body. You can't say, oh, that sits really nicely, the helmet closes off beautifully, that'll definitely make me faster. No, doesn't have to. Doesn't have to at all. There's no guarantee. You have to measure. And that's what makes the objective difference. When you've tested things multiple times, built up a real feel for what aerodynamics is about. And one thing you can't forget in this whole story — it's fun when you can tinker, optimize your equipment, optimize your helmet, and then see, hey, the CdA is getting significantly better here. And I've had plenty of really good athletes who came in at 30 aero points and are now at 22, 23 aero points. They've all gotten so much faster. And that's really sensational. And you can achieve that. If you're already very good in aerodynamics, you obviously don't have as much potential. You can't pull out as much as quickly.

Sebastian: But if we want to test accurately — and maybe we should go into that a bit more precisely — you need a good test course. How do I find one? Either you set one up yourself — you can say something about that in a moment — or you can look at our platform.

Björn: Exactly. And that's a real opportunity. On our platform, if we've seen good test courses, we've published them there. And for every test course, an average measurement error is also given. You can relatively quickly see what good and bad test courses are. Good test courses are where the average measurement error is under two percent — excellent test courses. Bad test courses are usually over four percent measurement error. And then you can say, okay, it'd be nice to find a different test course. An important prerequisite for the test — and now we're getting a bit deeper, so for those just starting out, it might be good to come back to what I'm saying now. Because sometimes if you get too much info, you say, oh my god, I have to think about all this, and it becomes too much. That's why I recommend this step-by-step start. The wind should come from the side. Here in Flensburg, in northern Germany, it's relatively simple. Either the wind almost always comes from the west, and if it doesn't come from the west, it comes from the east. That's why you can pick a north-south route here and basically always have perfect wind conditions. The key for the test is that the wind comes from the side. Check the main wind direction where you're located and try to make it so the wind comes from the side. Then it's great. If on the other hand you have a course that goes through heavy vegetation, with foliage on both sides, that's also great. You can use that. But if the foliage is so thick that the trees grow really tall and the sky is closed off above, then it becomes problematic because the GPS fails again. Unfortunately, the GPS coordinates become so bad that you lose measurement quality again. Otherwise, you can honestly say that if this test course is good, you also get excellent measurement results. So it's definitely possible, and you should invest a bit of time into this. I also don't think aerodynamics is something where I say, okay, I'm convinced now, aerodynamics is for me, I'll do two tests and then I'll be better. If you decide to do this alone, you'll need a bit of time. That's just how it is. Promising anything else wouldn't be true. You just need a bit of time to get in the groove and understand the system and then test. And when you're on your third session, your fourth session, you'll already see — you'll have a feel for it. What CdA do I actually have? What CdA do the others have? What do I need to pay attention to in the test? What are the nooks and crannies? And then it really starts to be fun because you can actually start improving yourself. And you already asked the right question. The most potential is in the seating position. That makes the biggest difference. And you can find that — via our website afasteryou.com, but also directly on YouTube, for example. We have lots of videos showing how you can improve from a seating position perspective. So what are the really decisive factors? For example, starting with the armrest width. How narrow are my elbows on the bars? You can almost always say that if they were narrower, you'd be faster. There are very few where it's the opposite. But it also shows how important it is to test, because in doubt you go really narrow, and maybe you can't breathe as well or feel uncomfortable in the position. And if you're not even faster with it — that's really bad. I'd personally always love to avoid that. And then how does it look with the rise — with my hands? Many know this praying mantis position or the high-hands position, where you try to hide your head behind your hands. That's also a 50-50 probability that you get faster or not. You can't say it per se. And what else is important — how do I hold my head properly? We have a YouTube video on that. What can I do with my shoulders? We have a YouTube video on that. What can I do with my hips? How do I manage to lengthen my back? If you always see on your photos that you have a really hunched back and wonder why, we have a video on that. For example, to explain briefly here — and the videos take time, and if we explain everything here in the podcast, we'll blow it up. But it's really interesting: if you want to really sit aerodynamically, you need to rotate your pelvis forward. Then your spine at the back of the pelvis doesn't go up so steeply — it goes flat forward. You become significantly longer. Two, three, four centimeters that you gain in the upper body length, because you don't have curves anymore. And that often reveals a problem — very often the top tube isn't long enough. I can't sit long because my bike doesn't let me sit long. And the other problem, which is about equally common, is pressure in the perineum area. When I tip my pelvis forward, I get significantly more pressure on the perineum, and if the saddle doesn't allow for that, I rotate my pelvis back again. Then I can't take an aerodynamic seating position because of that. And just as a rule of thumb — what does it mean if I can really lengthen my back or not? That's two or three aero points difference. Between someone who sits really hunched and someone who sits really long. And we're already at 20, 30 watts, depending on how fast you ride. These are the things where you can really say: this will make you faster. We've also had many athletes who got faster by raising the bars, not going lower. Because sometimes when I sit even lower, I get too much pressure on the perineum, or my hip flexor gets too tight. And then I start pushing myself up through my shoulders. Then you see how the upper shoulder area isn't relaxed at all. I'm pushing myself up so hard to get relief in the saddle area and not be so pinched. That means I'm not relaxed in the shoulder girdle anymore. And I push myself up awkwardly and then I also hold my head awkwardly. There it actually makes sense to go up two centimeters. But then be relaxed in the shoulder girdle and able to hold the head low. And suddenly I'm one aero point faster. Even though I went up two centimeters. Or I have the same aerodynamics. So there are really fascinating things that you wouldn't otherwise pick up. And you wouldn't pick up in a bike fitting either.

Sebastian: Yeah, we had that — the UCI has now basically banned that position, arms resting on the bars, on road bikes. But we have this in Bavaria. The criterium scene is probably a bit more familiar to some. There were riders who... really tilted their saddle nose down to drop perfectly into this position. Attacked and then rode only on their forearms, getting excellent aerodynamic values. So the bike wasn't even set up for riding in the drops anymore. It was only trimmed for an aerodynamic position, which is actually fascinating because we're talking about criteriums, where we go in circles and constantly have to accelerate. But the criteriums suddenly got a whole different spin — riders would accelerate and continue in an aerodynamic position. Really interesting developments. It's been toned down a bit now, but sure, people keep playing around with how I can work aerodynamically on the road bike, to be able to ride in an aerodynamic position as relaxed as possible.

Björn: Yeah, so you definitely have many options — with equipment, with the videos — to really look at what options you have, how can I improve aerodynamically. And with the test system I can use outside, I have all the options to implement it. And I think with that, we've shown a pretty good entry point now. I hope that was clear to most. So the process: come to the website, sign up, look at the description, look at the video, sign up. Do the first Aerotest outside, without much preparation, just go out, do the test. If you can install the app, use the app. If you can't install the app, just do the 1,000 meter test — think of a virtual start and end point and time it with your Garmin or Wahoo or Sigma or SRM or whatever device you use. Out there, take this file — for example recorded as a FIT file — and upload it to our platform. Just drag and drop it in, the system recognizes the test. Ideally you've stopped it where you were testing, so you can have the outbound and return — and later you can even have multiple tests in one FIT file. The system splits that automatically, it all works. And then you have your first CdA value. And then the journey begins: first find a better test course, then maybe test with the right bike once. And when the measurement error on the course is okay and you've gotten a feel for how it all works, then you start testing professionally. Then the equipment gets tested — what you have, maybe swapping with your friends. And once you have that, look at the YouTube videos again and think about how you can improve further. And fundamentally — if you make the aero tests you've done public on our platform, sharing them with the others, you also get feedback on your seating position. If you upload photos, perfect. Then we can immediately say something about your CdA value. How's your stability? Are the measurements okay? You get feedback from us, and you have a real chance — with the help of the community and the platform — to do optimal aero testing. Exactly. Okay. I think. Yeah, that was a bit of a monologue from me, but I think that's okay. And so, I'm curious now when we explain the next test of ours — the Powertest — you'll be in the good situation of being able to start your monologue. What I still find exciting is — when you're out there with your guys and running Aerotests, and you saw it at King of the Lake now — how well it can work, how fast you can be, how well the predictions match, and how it'll find application in all areas. Yeah, and there'll be more and more. More and more devices are coming out that can measure aerodynamics. And I think you have a really great facet there to engage with further. Yeah, absolutely. Absolutely.

Sebastian: Great, Björn. Thank you for your time, Sebastian. I hope — or rather we hope — you enjoyed this. In the meantime we're also looking for some intro music.

Björn: Yeah, and if you have questions or want to know something specific — this was a general overview and we can of course go into many other facets, we can do special topics on wheels or body positions or other aspects that seem interesting to you — then please write to us. We'd love to summarize it or work on it more intensively, whatever that may be, and offer you some added value. Great. Thanks a lot. See you. Ciao. Bye.