The Crazy World of Aerodynamic Advantages: Banned Aerodynamic Tricks in Professional Cycling

At the 2026 Tour de France Femmes, reports of padded sports bras caused a stir. The idea behind them was that a different breast shape could smooth out the airflow in the low time-trial position. The UCI responded by introducing additional clothing checks. This case is a prime example of an arms race in which the line between clever optimisation and unauthorised disguise is constantly being redrawn.

Aerodynamic tricks in professional cycling

At high speeds, aerodynamic drag is the dominant source of resistance. It increases sharply with speed and can be influenced by body position, clothing and the material used. TOUR measures these differences in a wind tunnel under standardised conditions. In the TOUR test procedure for aero road bikes Among other things, a kicking dummy, set speeds and various angles of approach are used.

Key factors can include how aerodynamically efficient the rider’s position is, how the clothing fits the body, and whether the handlebars, brake levers and forearms form as small a frontal area as possible. The optimisation concerns the entire rider-bike system. For years, teams and riders have been fine-tuning their set-ups and utilising every aerodynamic trick in the book. We look back at the frantic chase through the mudflats:

The body and clothing as an aerodynamic surface

‘Bra-Maxxing’ at the Tour de France Femmes

The most recent and most unusual case of aerodynamic trickery concerns the shape of the upper body. During the Tour de France Femmes, reports emerged that female riders were said to have worn oversized sports bras with extra padding. The aim was to create an artificial breast shape that could smooth the airflow whilst in the bent-over time trial position.

From a fluid dynamics perspective, this makes sense: an abrupt edge or an unfavourable shape can cause the airflow to separate prematurely. A modified contour could keep the airflow in contact with the body for longer. In motor racing, even a small advantage is enough if it remains consistent over many kilometres.

The UCI subsequently introduced additional clothing checks. The focus was on whether items of clothing alter the natural shape of the body in a way that goes beyond normal protective or comfort functions. This case illustrates how difficult it can be to objectively monitor a boundary when clothing is not only protective but is also specifically used as an aerodynamic component.

Aero pockets and front pockets

Jersey pockets also became a focus of optimisation. Riders used oversized or specially positioned front pockets to direct the oncoming airflow away from their upper body. What looks like extra storage space in everyday life can act as a small aerodynamic fairing when in a low racing position.

The UCI was quick to ban such aero tricks. A bag may serve its practical purpose, but it must not become a freely customisable aero profile.

Hydration bladders under the jersey

In time trials, water bladders were sometimes worn under the jersey. As with other aerodynamic tricks, this was not solely about hydration. The additional shape beneath the clothing could affect aerodynamics.

From the teams’ point of view, the solution was appealing because it required no visible additional parts. That was precisely what made it difficult to monitor. The UCI eventually banned its use once the hydration bladder was no longer regarded merely as a drinking system, but as a structural element.

Remcos overshoes

At the 2019 World Time Trial Championships, Remco Evenepoel exploited a loophole between the official checks and the actual race situation. Before the start, he complied with the sock height regulations by rolling his overshoes down to the permitted length. Shortly after the race began, he rolled them back up again.

The trick was simple but effective: longer overshoes can reduce turbulence around the lower leg and the shoe. It was not so much the material as the timing of the check that was crucial. The episode made it clear that a rule only works reliably if the conditions under which it is checked are also clearly defined.

Castelli Body Paint and its textured finish

At the start of the 2017 Tour de France, Team Sky opted for a time trial suit from Castelli. The so-called ‘body-paint’ suit featured a textured surface with indentations on the arms. This texture was designed to create controlled vortices and thereby influence the airflow.

Such surfaces are familiar from the aerodynamics of other sports. Small features can alter the flow over a surface and delay the transition to unfavourable separation. In cycling, this effect was of particular interest because, in the time-trial position, the arms make up a large proportion of the surface area exposed to the oncoming airflow.

It took two years for the UCI to amend its regulations. Restrictions were placed on changes to the surface texture of racing kit, meaning that the suit, in that form, was no longer compliant with the rules. This episode is seen as an example of how technical development can exploit loopholes in the rules and how aerodynamic tricks only work for a short time.

Aerodynamic tricks: the battle for the narrowest front end

Brake levers angled inwards

One particularly striking development concerned the brake levers. Riders turned them sharply inwards to narrow the front profile. In some cases, this allowed their forearms to rest more flatly on the handlebars. On a standard road bike, this resulted in a riding position reminiscent of the armrests on a time trial bike.

From an aerodynamic point of view, the idea was obvious: less width means less surface area exposed to the airflow. At the same time, control over the bike changed. The brake levers were no longer positioned where one would expect them to be for ergonomic and safety reasons. The UCI therefore introduced new regulations governing the position of the brake levers to prevent this aerodynamic trick.

The prohibited forearm position

Even more direct was the so-called forearm position. Riders placed their forearms on the centre of the road bike handlebars to mimic the compact posture of a time trialist. The upper body dropped, and the frontal area was reduced.

The problem lay in riding safety. In this position, access to the brakes and steering controls is limited. Furthermore, it is more difficult to stabilise the bike when encountering bumps or sudden movements. The UCI therefore banned this position outside of time trials, where fixed supports and defined armrests are used.

The UCI explicitly cites safety reasons for the changes to the forearm support and handlebar dimensions – one of many banned aero tricks.

Super-narrow handlebars to be banned from 2026

Particularly narrow handlebars were the next step towards reducing the frontal area. Some riders reduced the width drastically in order to slice through the wind as narrowly as possible. However, in sprints, on bends and in a tight peloton, handlebars that are too narrow can compromise control and stability.

Since 1 January 2026, a minimum width of 400 millimetres – measured from outer edge to outer edge – has therefore applied to road and cyclo-cross races with a mass start. In addition, the UCI stipulates a minimum width between the brake levers. The rule not only restricts extreme aero positions, but is also intended to ensure that riders, regardless of their height, have a cockpit that is sufficiently controllable.

Tips for your bike and kit

Insulating tape for Di2 junction boxes and cables

Before wireless shifting systems became widespread, cables and junction boxes were among the minor sources of interference on road bikes. Mechanics used smooth insulating tape to secure Di2 junction boxes and cables to the frame. The tape was intended to smooth out any rough edges and prevent individual cables from being exposed to the airflow.

The effort involved was manageable, and the benefit was probably minimal. In professional cycling, however, even a small advantage counts if it can be achieved without adding weight and with minimal effort. With the latest wireless groupsets, this problem has largely disappeared on many road bikes.

Tadej Pogačar’s Aero Bottom Bracket

Tadej Pogačar uses a bespoke bottom bracket shell known as the Bikone BSA Road Ceramic Aero UAE Bottom Bracket. A striking feature is the completely smooth non-drive side. This is designed to improve the aerodynamics of the area around the bottom bracket.

The advantage lies in a detail that is easily overlooked in conventional bottom bracket solutions. At the same time, the component highlights the trade-off inherent in modern aerodynamic optimisation: installation is complicated and can only be carried out using specialist tools. What can save seconds in racing is significantly less practical when it comes to maintenance and servicing.

The aerodynamic advantage behind the support vehicle

The air bubble made from spare tyres

Support vehicles were also incorporated into the search for aerodynamic advantages. During time trials, teams would stack numerous spare bikes on the roof racks of their vehicles. Fluid dynamics calculations showed that a dense wall of bikes could push an air bubble forwards.

This was intended to reduce the air resistance experienced by the rider in front of the vehicle slightly. The effect was small, but significant in the battle for seconds. The UCI responded by increasing the mandatory distance between the team car and the time trialist.

This case shows that aerodynamics do not end at the seat tube. The rider’s immediate surroundings can also affect the airflow. This is precisely why the competition rules cover not only the bicycle and clothing, but also the behaviour of support vehicles.

Drafting: the classic advantage

The ultimate aero advantage remains the slipstream behind a motorbike or a team car. Following a crash or a breakdown, it is often accepted for a rider to use this to catch up with the peloton again. However, if the gap becomes too small or the advantage too great, this may constitute a breach of the rules.

In 2019, Dutch cyclist Nils Eekhoff thought he had won the U23 World Road Race title. Shortly afterwards, he was disqualified for drafting behind the team car. The incident highlighted just how fine the line can be between a permitted return to the race and unauthorised assistance.

Jan-Willem van Schip, the most tenacious aero tinkerer

Jan-Willem van Schip, a Dutch professional cyclist and world and European track champion, has earned a special reputation as the peloton’s aerodynamics tinker. He tests the limits of the regulations not only in theory, but also in actual races.

In the past, van Schip used particularly narrow handlebars, which meant he repeatedly came under scrutiny from the race officials. In 2026, the 31-year-old, who rides for the third-division team Azerion/Villa Valkenburg, was disqualified on three separate occasions.

At the Tour of Holland, the issue was an upside-down seat post. At the Tour of Hellas, his position was called into question. At the Ronde de l’Oise, he was initially fined 200 Swiss francs and was later disqualified from the race altogether, this time officially for having a water bottle under his jersey.

Particularly controversial: in every instance, a commissaire had approved his bike as compliant with the rules before the start. Van Schip and the UCI are therefore unlikely to become friends any time soon. His team hinted at a split, stating that the recurring disputes with the commissaires were becoming an increasing burden. Fans compare van Schip to the aero pioneer Graeme Obree. Others see him primarily as a rider who pushes the rules to their very limits.

Innovation or a sham?

The history of aerodynamic innovations in professional cycling follows a recurring pattern. First, a team discovers a way to improve airflow. Then the solution is copied, becoming more visible and more extreme. Finally, the UCI responds with a more precise rule.

Not every unusual solution is automatically unfair. Aerodynamics is part of the technical evolution of cycling. A smoother bottom bracket, well-fitting cycling kit or an efficiently shaped frame can all be legitimate advances. Problems arise when clothing is specifically designed to cover the body, when riding positions impair control, or when support vehicles create additional slipstream.

The next aerodynamic trick is unlikely to come from an obvious source. Perhaps it lies in the rider’s kit, in an inconspicuous component, or in the rider’s immediate surroundings. One thing is certain: as soon as it becomes visible in a race, the UCI will be looking very closely.