Video: 3D printed Tom Dumoulin employed during pre-Tour aero testing

First on stage 13 and second on stage 18, Tom Dumoulin has been performing well in the time trials at this year’s Tour de France. One aspect of his preparation apparently involved testing out skinsuits using a 3D printout of himself.

Delft University of Technology (TU Delft) reports that a team of researchers scanned Dumoulin from head to toe and then created a 3D mannequin. They then subjected it to a series of aerodynamic tests.

Earlier in the year, Dumoulin took the race lead in the Giro d’Italia after finishing just 22 thousandths of a second ahead of Primoz Roglic in the opening time trial. You can see why he might be keen to grab every advantage he can.

“It’s split seconds that count in cycling, especially during a time trial, so if a faster suit can deliver only a small improvement, this can still make the difference,” he said.

But why a 3D printout of Dumoulin and not the man himself? The answer, it seems, was time.

“Scientifically speaking, you’d ideally have unlimited access to the athlete, in order to conduct extensive wind tunnel tests and develop the perfect suit for them specifically. However, you can’t place a professional cyclist in a wind tunnel for weeks on end.

“The consequent idea developed at the TU Delft was to not place the cyclist himself, in this case Tom Dumoulin, in the wind tunnel, but a mannequin with the exact same physical measurements. An even more important upside to the use of a mannequin in the wind tunnel: it remains perfectly still, so measuring the airflows around the body becomes much quicker and more accurate.”

The Dumoulin mannequin was printed in eight parts and then put together with pin and hole joints. It then went to Wouter Terra, a PhD-student at the Faculty of Aerospace Engineering, who took measurements in the TU Delft wind tunnel, using different suits and materials.

Terra said a “clear difference in drag” was measured between the various materials and he points out that even small differences can prove crucial. “A difference of just one percent in drag, to name but a number, might not seem much, but can result in a time saving of about ten seconds in an hour-long time trial.”