The Handlebar Design Revolution

Handlebars are arguably the quickest evolving component in endurance track racing. Recent years have seen the size and shape drastically modified. But why change from the traditional Merckx style bar? And how are the recent innovations helping us ride faster? The answer: aerodynamics.

Eddy Merckx during the hour record in 1972 (Photo credit: James Lockwood photography)

Handlebars have always been known as an important contact point between rider and bike. Much of a rider’s control and comfort is determined by this one component. More recently though, handlebar innovation is being driven by aerodynamics.

The handlebar plays two vital roles in the aero package of a track cyclist:

1. It affects how the rider positions their body through the airflow. When you compare the size of a rider’s body to a track bike from a front-on view in the image below, you can see how body position is the biggest contributing factor towards generating drag forces. A general rule is that body position accounts for 80+% of the total drag force experienced at racing speeds, with the bike accounting for the remaining drag and friction losses. Handlebars are versatile in the way they can manipulate the body shape cutting through the air in several ways.
   
   

   Dutch track cyclist Matthijs Büchli visits the DNW wind tunnel, 2019. (Photo credit: DNW)

    

2. It is a leading edge which means it is the first part of the system to hit the wind. This makes the shape and size have an important influence on how the air travels over the bars themselves and then onto the objects downstream.

Optimising these two aspects (body position and handlebar shape) can lower the overall drag coefficient and frontal area of a cyclist (also called “CdA”), which results in a cyclist requiring less power output for a given speed. Handlebars are an aero enabler, and should be thought about as more of a component within a system rather than independently.

Development of Handlebars

You don’t have to turn back the clock far to see radical differences in handlebar design for track endurance events. A few olympic cycles ago you would be far fetched to find any non-road compatible handlebars. Despite the advances in aero testing facilities, it has taken a while for the industry to realise the potential in optimising handlebars. Here are five design changes to handlebars that are helping drive world class performances and making equipment romantics quiver.

Handlebar Width

Traditional widths have always been 40 cm or wider for road racing. Bike fitting began to buck this trend, with riders being fitted to handlebars that match shoulder width. Smaller framed riders hence started to adopt 38 cm and 36 cm width bars. The theory behind this was to avoid strain through your upper body by aligning your wrist and shoulders. This may hold true and be important for long distance events. However where performance and speed are of high priority, sacrifices to comfort are sometimes made. That’s why track cyclists were earlier to adopt narrower bars, having shorter and faster races. Athletes performing at a high level are usually incorporating strength and conditioning training into their training program, which can help absorb some of the more extreme positions.

The big change to handlebar width happened when aerodynamicists and equipment developers began to explore functionality of narrow handlebars and the effects of on a cyclist’s CdA. Their findings of reduced frontal area and a more aerodynamic posture has led to the transition towards racing on bars as narrow as 27cm. There are stories of even narrower bars being tested but we are yet to see them used at a major event. Bringing a rider’s arms closer together results in a more streamlined airflow and minimises frontal area by negating splayed elbows and bars. 

Handlebar Placement

To adopt narrow handlebars and avoid a rider’s knees and elbows colliding, the reach of the bike must be long enough. This realisation sparked the need for longer bikes and stems, resulting in a position akin to Campbell Stewart’s below. Fortunately the 2023 UCI rule change to allow longer reach has made these positions possible. You can now run handlebars 100 mm beyond the front axle, compared to 50 mm previously.

Campbell Stweart (Photo credit: Darjo Bellingheri, 2023)

Another driver behind running track handlebars with more reach is the lack of shifter/brake levers on track bikes. Road bike shifters bring your hands further in front, seen below by how much further in front the contact point is on a shifter. This difference needs to be made up in track positions so stems and frames are generally longer.

Road bike handlebars with shifters (photo credit: FSA)

Aero Profiled Tubing

A cylinder does not cut through the air efficiently. Below are simulations of air flow over a circular cross section (left) and an aerofoil cross section (right). You can see how the aerofoil shape has a much smaller wake.

     

To date, the majority of designs focus on the bar itself and in an isolated environment. But brands like Ribble have attempted to use shapes that manipulate the airflow to better interact with objects downstream. This concept is highly rider dependent and requires extensive testing to validate. But the idea is to have less of a high pressure zone at the downstream object by disturbing the incoming high speed flow.

Ribble’s handlebar for the Ultra SL R. (Photo credit: Ribble)

This is unlike most aero handlebars which focus on the least amount of flow ‘separation’. When the flow separates, a low pressure zone forms behind the object. It’s the difference between this zone and the high pressure zone at the front that causes the resultant pressure drag. In most scenarios this slows you down, so most handlebars aim for minimal flow separation, seen by the laminar streamlines below.

Velobike Skat handlebar with Grip C

Shape

Ergonomics remain an important part of handlebar design so there have been many iterations of the drop handlebar over the years. There was a shift from ‘traditional’ to ‘compact’ as it was realised an aggressive hood position is good for aerodynamics. Running compact bars allows the drops to remain in the same place whilst lowering the hood position.

Corbin Strong (Photo credit: Eugene Bonthuys)

Integration

Integrated cockpits are now ubiquitous in pro road cycling. Track cycling is different in that the priority has always been fitting for total system aero over individual component aero. Despite this, certain teams with ample budgets are investing in one-piece cockpits tailored to individual rider specifications in preparation for the Paris Olympics. Bike fits are dynamic, and as trends evolve and individual fits progress, these athletes may opt to change back to a modular system in the future.

Conclusion

While there has been extensive research into optimising time trial and pursuit positions, endurance track handlebars remain a relatively untouched space prior to 2020. This might be due to the complexity of simulating mid-bunch aerodynamics. Wind tunnel testing is less applicable when aerodynamic ‘wash’ from the other riders is at play. Now that CFD (computational fluid dynamics) is becoming more widely used and understood, simulations of cycling through turbulent flow are likely to drive future innovations and we will see more design changes to the traditional drop bar.

CFD simulation of cyclist (Photo credit: INEOS grenadiers ready to take on 2024, Youtube video)

The gradual acceptance of concepts like narrow handlebars has been slow. This could be to do with riders seeking to mirror their road positions. But track cycling is a distinct discipline with unique demands. By acknowledging the distinctive nature of track cycling and adapting equipment accordingly, riders can enhance their performance. We are already seeing the correlation between willingness to adapt and success with world class track riders. It will be exciting to see this attitude catch on and continue contributing to the sport’s growing momentum.

Written by Dan Gardner as part of an Engineering internship with Velobike Innovation