Ride faster with the right bottle placement on your bike

An aerodynamics guru reveals the best place for bottles on your bike to give you a faster bike split.

Former team lead of aerodynamics and future innovations for Specialized Bicycles, Ingmar Jungnickel ran several scenarios through a computer airflow simulator. He looked at bottle positions that increase drag and how air flow around certain set ups actually make you faster.

“Bottles on the downtube or seat tube only increase the drag on your bike and are a missed opportunity in triathlon,” said Jungnickel.

“Since your body causes three to five times more drag than your bike, using the bottles to improve the airflow over the rider can actually lead to significant drag reductions.”

The best bottle placement

The testing confirmed several configurations for bottle placement that are optimal. One is behind and close to the seat in a horizontal position. Placing bottles between the arms, such as in a jersey, also proved to offer a performance benefit.

This second scenario is dependent on a rider’s position on the bike, but regardless it can save time simply due to ease of access. Being able to reach for a bottle between your arms allows you to remain in the aero position, maintaining speed gains.

To determine these findings, Jungnickel simulated a rider and bottles using the sophisticated software. He used two different bike positions and several bottle placement scenarios. He did not include a bike or bottle cages in the simulation. This method helped manage simulation time and effort.

“This is a limitation of the study and something to keep in mind,” he explained. “The first position is a good but more upright position, as is common for a fast long course rider. The second position is a very aerodynamic tuck, for a very aero short course racer, or pro time trialist.”

He ran multiple scenarios through the simulator, including bottles between the arms, behind the seat at varying distances and angles, and tucked in a rear jersey pocket.

Potentially save minutes in a race

“Behind the seat bottles should be almost horizontal and as close to the rider as possible, and should be mounted at seat height or slightly higher,” he said. “In those positions, they provided substantial drag savings over no bottles at all, saving one and a half minutes of the the Ironman distance.

“This is comparable to switching from an aero road helmet to a full blown time trial helmet.”

There was some variation depending on rider position. The most upright rider saw gains with either one or two bottles placed between the arms. Time savings produced were almost two minutes per 180 kilometres.

A more aero position with dropped head omitted the option to carry two bottles between the arms due to the position. One bottle actually proved slower than no bottle at all, with a recorded loss of about 40 seconds over the Ironman distance.

The results emphasized how personal aero gains can be.

“As computers get faster and cheaper, the ability to tailor aerodynamics to the individual athlete at an affordable price may be the future,” added Jungnickel.

Computer airflow simulation practical for the masses

With nutrition being such a critical component of racing well, particularly at long distance, finding the optimal bottle placement is an obvious edge.

“The relatively flat profiles of most triathlons mean the weight penalty has a minimal effect and the rules allow for a lot of flexibility in bottle position, so there stands nothing in the way to bring your own hydration,” he concluded.

After years of testing aerodynamics design and leading innovation on Specialized’s Venge, Tarmac, Roubaix and Shiv TT bikes, Jungnickel remains focused on testing data to help make athletes faster. He now runs Inspire Gold, a high-performance Research and Design lab with clients from Olympic teams across different speed sports and companies.

The choice of using a computer airflow simulator is practical and in some ways more accurate when testing data for age group athletes.

“Computer airflow simulation (CFD) is an excellent tool and alternative to wind tunnel testing since it is 90 per cent cheaper, perfectly repeatable and has an accuracy that approaches tunnel testing.

“For amateur riders that are often not very repeatable in a the tunnel, CFD can actually give better answers.”