LEARN
AERODYNAMIC DRAG
Aerodynamic drag is one of the main resistive forces that slow you down whilst cycling, and at racing speeds is a large factor in determining your overall performance. Other forces include rolling resistance and the effect of gravity, which become more important as the steepness of the road increases.
Aerodynamic drag is measured in CdA, which consists of two factors: your frontal area (A, measured in m²) as well as the drag coefficient of the shape (Cd, a dimensionless value). These two combine to give a CdA in m². The lower your CdA the more aerodynamic you are, and the faster you can ride with the same power output.
A rider's shape when sat on the bike is described as a "bluff body" in aerodynamic terms, and streamlining a bluff body is more difficult than a typical airfoil shape, such as the downtube of the bicycle.
A small reduction in aerodynamic drag can have a large impact on your race performance - for example a rider completing a 25 mile/40km time trial in 1hr will reduce their finishing time by around 30sec for just a 2% reduction in their CdA.
Longer events such as Ironman triathlon bike legs (112 miles/180km) can see many minutes worth of savings with better positioning and equipment.
In AeroCoach sessions typical CdA reductions are between 5-15%, resulting in large performance improvements of 15-35w .
See our posts below for free test data, and learn how we use wind tunnels, indoor velodromes and outdoors to improve and explore aerodynamic drag.
AERO TESTING SESSIONS
AeroCoach are experts in analysing and improving aerodynamic drag having optimised over 1400 riders, and offer test sessions in various locations, ranging from wind tunnels to indoor velodromes and outdoor velodromes.
When you arrive at the test location you have a briefing with the test analyst before starting your warm up. If you're at a velodrome, there's no need to worry if you've not ridden track before! Many riders coming to AeroCoach sessions are new to the track but the process is very simple and you don't ever ride high up the banking.
During the course of the session you complete a number of runs - each run consists of pedalling intervals (wind tunnel) or laps of the track (velodrome) where we have changed something about your equipment or position. For example we may change your aero helmet, or make an adjustment to your saddle or handlebars. Each run will provide us with data that is compared to your starting position to see how the change has affected your aerodynamic drag.
The goal of the session is to get you into a faster position with the best equipment setup - this is not always the position that just results in the lowest aerodynamic drag. We have extensive experience with a wide range of riders and know that power production is key, not just a super low CdA. At the end of the session you have a debrief with the test analyst, explaining the results and answering any questions you may have before your report is prepared.
To book an AeroCoach session and to check availability, click the button below:
FREE TEST DATA
At AeroCoach we perform internal testing for product development as well as external testing for commercial clients.
To help speed you up, feel free to browse through our published data below, including information on rolling resistance as well as aerodynamic drag.
The new Continental Aero 111 tyre is designed to provide maximal aerodynamic advantage by use of a custom tread pattern. However there is often a tradeoff between aerodynamics and rolling resistance (Crr) in terms of how tyres are shaped and how this affects Crr, and understanding how the two combine to provide the overall fastest system is essential when looking to improve performance on the bike.
This test explores the difference in rolling resistance between clincher and tubular track racing tyres. Vittoria, Veloflex, Dugast and Continental tyres are compared at different inflation pressures.
Chris Hall came to visit us at AeroCoach HQ in order to improve his bike fit on his Cervélo road bike, specifically focusing on aerodynamics for road bike time trials. Holding different positions such as in the drops, the breakaway aero position and on the hoods we explored the impact on Chris' body position and how that would relate to his aerodynamic drag.
Watch the video to improve your road bike fit for aerodynamics: Xavier and Chris discuss narrow handlebars, turned in levers, torso angle, aero helmets and more!
Ensuring you have the best equipment during high speed track cycling events is extremely important. This data set provides information on the best tubular track tires/tyres for rolling resistance/Crr.
In 2023 there are new regulations for UCI time trial positions, relating to extension reach and shifter height, based on rider height. AeroCoach offer a range of options for our Ascalon extensions to achieve all possible combinations for the three rider height categories. Please see our TT position video below for an overview of the changes, and scroll down for the Ascalon options. PlePlea
Aerobar extensions, whether used on a triathlon/TT bike or using a clip on system on a road bike, come in a wide variety of sizes and shapes. AeroCoach has been testing riders since 2012 and we've noticed a few trends into how you can optimally hold your extensions for aerodynamics as well as comfort. Your body accounts for around 80% of the aerodynamic drag of the bike and rider system. Your optimal stack height, extension reach and elbow width for aerodynamics will be individual and can only be determined by conducting an aero test, but as well as these variables there are differences in how riders hold their hands on extensions, and in this test we explored some general guidelines which you can follow. Don't forget, a lower aerodynamic drag will result in less power required to travel at the same speed, or for the same power will cause an increase in riding speed, when not travelling up steep gradients.
In the UK, having a front light when racing time trials is now obligatory under CTT regulations. Not only this, but also some events are conducted over long periods of time (eg. 24hrs, or multi day ultra endurance rides) and so with front lights being a necessity we explored the impact of front lights on racing aeroydnamics in the wind tunnel.
Using clip on aerobars on a road bike is a great way to improve your aeroydnamics. Your body accounts for around 80% of the aerodynamic drag of the bike and rider system. In this test we explore the impact of holding different positions on a standard drop handlebar, alongside an aerobar position using a set of Ascalon extensions. A lower aerodynamic drag will result in less power required to travel at the same speed, or for the same power will cause an increase in riding speed, when not travelling up steep gradients.
The UCI have banned and outlawed some aero positions, such as riding using your forearms as a point of contact. What is the impact of turning the lever hoods inwards or riding with an illegal position with the forearms on aerodynamic drag? What is faster?
Road tubeless liners or inserts are used to provide extra security in the case of a tubeless blowout. In this test we explored their impact on the rolling resistance of a tubeless tyre.
How does volume of tubeless sealant affect rolling resistance? We did a test exploring 0-100ml of sealant and the impact on Crr in a Continental GP5000 TL tyre.
This test compared 3 lightweight racing tyres from Vittoria, Schwalbe and Michelin against the stalwart Continental GP5000 for real world speed.
In this video we explore different ways to improve your aerodynamics for free along with Global Cycling Network
Check your tyre pressures for racing with our handy wheel calculator, and see more about the aerodynamics of tyres with AEOX TITAN and ZEPHYR wheels
A combined test looking at the rolling resistance as well as aerodynamic performance of Continental's GP4000 and GP5000 tyres
Choosing where to put your hydration for a triathlon is important - have a look at the effect of hydration location in this velodrome test
It's not just tyres that reduce your rolling resistance - inner tubes matter too! We performed a comprehensive test on a variety of inner tubes to find out which ones are the fastest
Choosing the right tyre for racing is critical to your performance. Find information here on the lowest rolling resistance tyres and how the best tubeless and clincher tyres compare in terms of best rolling resistance.
How do two bikes from the 1990s (Lotus 110 & Zipp 3001) perform against a more modern bike (Cervelo P5-3)? This wind tunnel test explores the comparison between the three