Bicycle.Engineering

Bicycle.Engineering Bicycle.engineering develops bicycle parts and frames that are licensed to factories that produce an

: your aero advantage might not be what the number suggests, part 1.We split this into multiple parts, because it is a ...
02/06/2026

: your aero advantage might not be what the number suggests, part 1.

We split this into multiple parts, because it is a big topic: aero claims are often true, but at the same time implying bigger gains than there really are.

But first, let me state this: aero gains are absolutely real, und you are benefitting from them. They just might not be as big as you think. Also, aerodynamic drag will most likely be your main resistance during riding.

In this part: how did we get to this point where most aero testing ends up in numbers that are very hard to achieve in real-world use? I believe it is mainly that everyone involved has an interest in believing or making others believe that those gains found are big.
Media that invests in aero testing: They must convince their readership that it is relevant, otherwise they just wasted a lot of money and time.
Same goes for manufacturer that invest a lot of R&D in aerodynamics. Often involved external partners that specialize in aerodynamics. Obviously their work is only justified if the outcome is relevant.
Wind tunnels and companies offering other ways to measure aerodynamic drag: obviously more people are interested in buying their services and products if what you measure is significant.
Athletes: Being convinced that you benefit from all the aero testing is a mental advantage.
Consumers: You want to believe that you benefit from that aerodynamic upgrade you spent your hard-earned money on.

So once you are convinced that aerodynamics are relevant (which you should!), it is also beneficial to you to believe those gains are big.

Follow us for the next part where we explore how numbers can be real but inflated at the same time.

: Last year, I wore through a set of road tires all the way to the threads. What surprised me wasn’t just that I had ri...
26/05/2026

: Last year, I wore through a set of road tires all the way to the threads. What surprised me wasn’t just that I had ridden enough to do that again, but how differently the tires aged compared to the 23–25 mm tires I used to ride at a younger age.

Narrow, high-pressure tires would quickly develop a flat spot in the center tread, giving them a noticeably squared-off profile after a few hundred kilometers.

Modern wider tires seem to wear much more evenly. Lower pressures and larger air volume distribute the load better, so the tire maintains its intended round shape for much longer.

The obvious benefit is increased tire life.

But there may be another, much less discussed advantage: aerodynamics.

Your front tire is just as exposed to airflow as your rim. And a squared-off tire with a flat leading edge is probably not a very aerodynamic shape anymore.

Which raises an interesting question:

After some real-world wear, could a well-shaped 30 mm tire end up being just as aerodynamic as a worn 25 mm tire?

: the bicycle industry has established standards that give a very distorted picture when comparing different performanc...
19/05/2026

: the bicycle industry has established standards that give a very distorted picture when comparing different performance gains. For example, aerodynamic gains are often communicated as measured in the wind tunnel at a speed of 45 km/h. Meanwhile, bicyclerollingresistance.com publishes rolling resistance at 29 km/h for a single wheel. Now how do the two compare? In this graph we plotted the gains at different speeds for 7 W savings in the wind tunnel (full aero bike vs. good allrounder) and 4 W published by bicyclerollingresistance.com (Continental Grand Prix TR vs. Continental Grand Prix 5000 S TR). You will be probably susprised to see that at speeds that are relevant for most riders, those 4 W in rolling resistance are worth a lot more than 7 W in the wind tunnel.
Also a fact worth highlighting is that at 15 km/h, a speed at which you are likely in climbing and putting out meaningful power, you still get 4 W of gains from rolling resistance, but just 0.3 W from aerodynamics.

: Today we show why we are often doing the same work multiple times. To achieve the best result, we try different tools...
05/05/2026

: Today we show why we are often doing the same work multiple times. To achieve the best result, we try different tools and different settings. Even though they all seem to do the same, the differences can be quite significant.
The example shown here is quite simple, a profile that tapers at two different rates, with a smooth transition in between. But using native Solidworks tools, we got some waviness in the transition. Instead, we used the blend surface tool of the GW3D AddIn for the primary surfaces, and the xNurbs AddIn for the transition, achieving the smoothness we are striving for.

: Third (and maybe final—tell us if you want more) installment of our CAD design series.This time: the dropout for the ...
28/04/2026

: Third (and maybe final—tell us if you want more) installment of our CAD design series.

This time: the dropout for the UDH hanger. It requires a relatively large, planar circular interface for proper clamping. Our solution is a subtle raised dome that sits just proud of the surrounding surface.

The sharp edge clearly defines the masking boundary for painting, while keeping the overall dropout compact and avoiding unnecessary material buildup.

Swipe through to see how we build it—surface by surface.

: After last week’s post got such a great response, here’s another look into our CAD process.Once the geometry is defin...
21/04/2026

: After last week’s post got such a great response, here’s another look into our CAD process.

Once the geometry is defined - and kinematics sorted (for full-suspension designs) - and all component interfaces are in place, we usually start by modeling the front side of the head tube and the upper end of the seat tube.

These areas might seem simple, but they form the foundation for positioning the outer edge(s) of the top tube. Getting this placement right is key to achieving a smooth, continuous transition between tubes - as you can see in the following steps when the seat tube–top tube connection comes together.

: We saw another exciting last Sunday, and Michael Valgren was kind enough to upload his power file to Strave, so we ...
07/04/2026

: We saw another exciting last Sunday, and Michael Valgren was kind enough to upload his power file to Strave, so we could run it through our simulator. We applied our standard changes: 1 kg of mass, 7 W of aerodynamic drag at 45 km/h, 4 W of rolling resistance at 29 km/h and 2% of drivetrain efficiency.
A few observations: 7 W in the wind tunnel equalling 5.1 W in normalized power on the road is a lot more than we usually see. As almost always true, the higher the intensity the closer the importance of weight vs. aerodynamics gets. And even though aerodynamics have a higher importance here than in other races we analyzed before, rolling resistance and drivetrain efficiency still have more of an impact.

: In a recent podcast of by , 's Ingmar Junickel stated that the importance of high yaw angles in cycling is often ov...
31/03/2026

: In a recent podcast of by , 's Ingmar Junickel stated that the importance of high yaw angles in cycling is often overstated, probably because it makes aerodynamic gains look bigger. That is a statement I can agree with, even though I see also other ways how people ended up thinking high yaw is more likely than it really is. But how much of a difference does the weighting function make when looking at weighted averages? I looked at wind tunnel tests we did for ' wheels at 3 different standard deviations, 10°, 7.5° and 5°. The ranking of the wheels did not change, but the difference between the 35 mm Faserwerk Bergreif and the 55 mm DT Swiss ARC1100 shrank from 5 W to 3 W.

: In our development work, we’re less interested in optimizing performance averaged over an entire ride. What really ma...
24/03/2026

: In our development work, we’re less interested in optimizing performance averaged over an entire ride. What really matters are the moments where it counts.

One parameter we look at is gross W′ used - in simple terms, the amount of work you do above your second lactate threshold. If we can reduce that through equipment optimization, it means the ride gets easier exactly where it hurts most - the moments when you’re suffering and trying not to get dropped from the group.

What we found:

• Anaerobic efforts happen at high power. The higher the power output, the more you benefit from drivetrain efficiency. In those moments, an efficient drivetrain is your best friend.

• Many of these efforts happen while climbing at relatively low speeds. That means aerodynamic improvements often matter less than wind tunnel numbers might suggest. But context matters: If your anaerobic effort is a sprint to the line or a surge to close a gap, aerodynamics suddenly become critical.

• Rolling resistance decreases at lower speeds, but it still remains one of the biggest performance gains available.

• Because many anaerobic efforts occur on climbs, weight savings can be just as important as aerodynamic improvements.

: One week ago I went for a longer road ride on my Callis gravel bike. I had a great ride, but after the ride I was as...
10/03/2026

: One week ago I went for a longer road ride on my Callis gravel bike. I had a great ride, but after the ride I was asking myself how much easier it would have been if I had my Velum available. I have the wind tunnel data for both bikes, Crr of both tires as measured by bicyclerollingresistance.com, so I put the numbers through our calculation tool. As it turns out, my ride would have been quite a bit easier on the Velum with a normalized power of 180.5 W instead of the 203.3 W on the Callis. The big ones are the tires, going from the (very fast) Hutchinson Caracal Race to the Continental GP5000 would have saved me 12.5 W. The massive 33.8 W @45 km/h difference in aerodynamic drag (my Callis currently does not have a Luftschneider, which makes for more than a fourth of the aerodynamik difference) lead to a 9.9 W higher NP.
However, just switching out the tires and the cockpit on my Callis would have reduced the difference to the Velum to just 0.4 W.

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