"I" is Josh and "we" refers to the test team.
CN took 11 of today's best road bikes (and an old 2015 rim brake bike as a baseline) to the wind tunnel for comparison testing to find out which one is fastest, which one is slowest, and how much faster they are than the baseline. We also did some additional testing on posture and wheel upgrades, which will be shared in the coming weeks.
CN reporters paid normal commercial rates for wind tunnel access and bought or borrowed all products used in the testing.
Our goal is to provide a range of high-end road bikes that strike a balance between products that consumers may want to buy and the bikes seen in the peloton of today's World Tour. We expect each brand to have similar levels of bikes, because while the aerodynamic differences between the two groupsets are negligible (superteam: not a small difference), we found that in some cases, the Dura-Ace / SRAM Red level bikes were equipped with integrated handlebars, while the cheaper models had a stem-bar combo. The premium bikes had wheels with aero spokes.
Some of the bikes in the test were "full aero", such as the Cervélo S5 and Scott Foil, while others fell more into the "all-around aero" category, such as the Specialized Tarmac and the new Trek Madone.
In alphabetical order, the bikes are as follows:
Cannondale SuperSix Evo 4 Hi-Mod Team Edition
Canyon Aeroad CFR
Cervélo S5
Factor OSTRO VAM
Giant Propel Advanced SL 0
Look 795 Blade RS
Pinarello Dogma F
Scott Foil RC Pro
Specialized S-Works Tarmac SL8
Trek Madone SLR 7 Gen 8
Van Rysel RCR Pro Team Replica
The base bike is as above: a 2015 Trek Emonda ALR with stock wheels, round drop handlebars, rim brakes, and external cable routing.
Each bike is a size 56cm or the brand’s closest equivalent.
To some extent, we were limited by what we could get. For example, we wanted to include Colnago V4Rs (for the Pogačar vs Vingegaard bike comparison), Merida Scultura, BMC Teammachine R, Bianchi Oltre, Enve Melee, the new Van Rysel aero bikes, etc.. Still, the bikes were not available and we tried to contact the brands but received no response.
We took the bikes to the wind tunnel at the Silverstone Sports Engineering Centre and tested the aerodynamics of each bike, measured in units of Drag Coefficient x Area (CdA).
This is quantified in square meters. The drag coefficient defines how easily air passes over the surface of an item and is largely affected by the shape of the item, but can also be affected by the material of the surface, which is why many cyclists wear aero socks rather than bare legs. The area is simply the frontal area or size of the item.
We did this in two tests - testing the bikes on their own, then testing the drag with a person on the bike - and we wanted to know three things:
1. Which bike is the fastest
2. Would you ignore aerodynamics when buying the next bike by testing it and focusing on other factors such as weight, comfort, specification, etc?
3. How much faster are they compared to our benchmark bike? We used the 2015 entry-level Trek Emonda ALR to represent the bike you've ridden for years or the entry-level model that recently sparked your passion, and we wanted to know how much improvement you could get by upgrading to a modern race bike.
The protocol was designed in-house with guidance from the aero experts at the SSE Hub.
We tested at seven yaw angles: -15, -10, -5, 0, +5, +10, and +15 degrees.
All tests were conducted at 40 km/h (24.85 mph), representing a typical amateur road race, fast club ride, or slow pro peloton (the average speed for the 2024 Tour de France is 41.4 km/h).
For the ride tests, we tested each yaw angle for 30 seconds. We could have tested longer times per test, but found this to be a good sweet spot, capturing enough time to get reliable data, but short enough to avoid fatigue causing repeatability failures and allowing us to test all bikes. Cadence has always kept around 90 RPM.
For the individual bike tests, we made sure the wheels were spinning at the correct speed; airflow behavior on a static wheel is very different from real-world riding and therefore not representative. For this test, we tested each yaw angle for 15 seconds. The data here is "cleaner" (no rider pedaling or holding position), so it can get higher accuracy without longer testing time.
We normalized many variables as much as possible, including bike fitting settings, water bottles, tires, etc. (We did a lot of normalization work and we will omit it for your reading experience)
Since not everyone is so concerned about data interpretation, the superteam will provide you with the conclusions of this test directly.
Cyclingnews does not claim that this data is the conclusion on bicycle aerodynamic performance but provides our readers with additional independent and unbiased testing and information flow.
The results are representative of our testing on that day. We hope that the clarity of our methodology and protocol will allow readers to appreciate the data while being more informed.
We also understand that other factors are equally important when buying a road bike, such as ride quality, weight, comfort, specs, tire clearance, aesthetics, customer experience, etc. The best road bike for you will be a balance of these features with aerodynamics, with each weighted according to your preferences.
Conclusion
The graph above shows the power required for each bike at 40 km/h. The Specialized Tarmac has a power of 280.2 watts (±3.91 watts margin of error).
The Look Blade 795 RS has a power of 286.29 watts, also with a 3.91-watt margin of error. Given this margin of error, the difference between superbikes can be minimal, but it can also be as much as 13.91 watts.
The base model Trek Emonda ALR has a power of 304.67 watts. Again, considering the margin of error, the S-Works Tarmac is at least 16.65 watts faster than the baseline bike, but it could be up to 32.29 watts faster.
Which bike is the fastest?
Although the Specialized Tarmac came in first in the rider + complete bike test, followed closely by the Trek Madone and Factor OSTRO VAM, other bikes could have taken the top spot in different tests due to the margin of error.
Therefore, it is difficult to draw absolute conclusions about the fastest road bike.
In addition, the rankings varied greatly at each different yaw angle, further indicating that the variability is greater than the differences between bikes. Although our margin of error reflects typical rider effects, combined with other factors and the closeness of the results, we cannot confidently say which bike is the absolute fastest. Therefore, we recommend focusing on other factors such as weight and ride quality when considering a purchase.
Looking at the data from the individual complete bike tests, the results are clearer and more consistent across the seven-yaw angles. The top of the list is populated by more aerodynamically focused bikes like Factor, Scott, and Cervélo, while the more “all-around” bikes also performed well, trailing by about 2-5 watts.
Considering the unweighted average CdA across the seven yaw angles, the Factor Ostro VAM was the fastest of the test, but it would have probably finished third after accounting for our margin of error. Given its weight on the day of 7.23 kg, this is still a very impressive result.
However, it could be argued that the Cervélo S5 was probably faster in real life, as it excels at low yaw angles.
The Cannondale SuperSix Evo also performed well as an “all-around bike”, and while it finished fifth on the day, it could have been as high as second given our CdA margin of error of 0.0010.
The only bike that lagged overall was the Look Blade 795 RS, which lagged by about 12 watts.
The baseline Trek Emonda was about 28 watts behind, which is about 40 watts behind the OSTRO VAM.
To answer our previous question: Are modern bikes all within such a narrow margin that manufacturers’ aero claims can be ignored? The answer is… sort of! While we weren’t able to confidently conclude which bike was the fastest, we found the slowest, and all of the superroad bikes performed significantly better than the baseline bike.
With this in mind, you can’t completely ignore aerodynamics when buying your next bike. Considering the difference in rider power between the best and worst bikes here can be as much as 13.90 watts, you can still lose speed if you don’t choose right.
Our advice
1. Aero isn’t everything
While aerodynamics can take priority when comparing bike performance, one thing we can learn here is that once you’re confident that you’re in the ballpark of aerodynamics, you can focus your attention elsewhere.
Whether you’re focused on weight, spec, or just your favorite bike color, it doesn’t matter, be yourself.
2. Anyone can ride fast
For the reasons above, the wattage savings here are calculated at 40 km/h, but we can extrapolate the CdA to different speeds to calculate the power savings.
Most enthusiastic amateurs will be able to maintain 30 km/h for a long time, and the difference provided at this speed is still significant. Upgrading from the Trek Emonda ALR to the fastest bike in the test, you can save 7.03 to 13.62 watts.
We think a bike you like is more important. Finally, if you like this kind of article, I hope you can comment and like it, so that we can increase the proportion of such articles!
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