Monday’s opening time trial at Tirreno-Adriatico, a no-frills, flat race on the Lido di Camaiore coastal road, passed largely unsurprisingly on the score sheet. World time trial champion Filippo Ganna took victory, finishing 11 seconds ahead of Remco Evenepoel and seven others ahead of Tadej Pogačar, the GC battle of the week unfolded in the wake of the ‘Italian.
However, beyond the power and precision of the Italian’s 17th time trial victory, some eagle-eyed viewers spotted something wrong – an abundance of spare bikes piled on top of the team car following him during the stage.
Ganna’s Ineos Grenadiers squad weren’t preparing for a Michael Rasmussen-style calamity on the 13.9 kilometer course, however – instead they were simply optimizing the aerodynamics of their star rider.
QuickStep-AlphaVinyl also did the same in the car behind Evenepoel, while the car following fourth-placed Kasper Asgreen had five bikes on the roof. Meanwhile, Pogačar’s and fifth-placed Dowsett’s cars contained only one standard spare bike.
The feat isn’t against UCI regulations – which don’t legislate the number of spare bikes on top of a team car – nor is it apparently a brand new one alluded to by Ineos’ new aero expert, Dan Bigham. Cycling news dug through photo and video archives and found that since the last stage of the 2021 Giro d’Italia, Ganna has gone from one or two spare bikes to the plethora seen on Monday.
In fact, he’s had a team car loaded with bikes that has followed him in three of the four time trials he’s raced for Ineos since – at the Etoile de Bessèges, the Tour de la Provence and Monday.
Ganna has, of course, won each of these stages – but what kind of gains can time trials get from being followed by a car with bikes packed on the roof rack? And how does the science of it all work?
Cycling news spoke to Richard Kelso – adjunct associate professor at the University of Adelaide with specialties in fluid mechanics, aerodynamics and sports engineering – to find out.
Kelso, whose aero expertise has seen him collaborate with AusCycling’s track team since 2008 and design several helmets with Kask and Scott, said Cycling news that – in addition to the well-known wake effect achieved by following a vehicle – having a vehicle follow a driver also gives an aerodynamic advantage.
“I think the way it’s normally explained is that any object moving through the air pushes air with it,” Kelso said. “The distribution of pressure around the object – in this case the car – leads to the air immediately ahead being pushed slightly forward.
“So that means the larger vehicle behind or the vehicle behind the rider will actually push the air forward with the rider, so the velocity of the airflow around the rider will be smaller. That’s is only small but it is enough [to make a difference].”
Like any object moving through the air, drivers and following cars create pressure fields, with a high pressure area ahead and a low pressure area behind. The difference between the two is what creates the drag.
Logically, then, with one object (in this case a following car within the UCI-regulated 10 meter gap during time trials) following another, the following car and its leading high pressure area will then have an effect on the back of the runner. low pressure area, thus reducing this drag.
“Depending on how far ahead the rider is, the rider will be sitting in the area where the air is pushed forward with the car,” Kelso explained.
“The maximum effect is right in front of the car, where the air is essentially moving with the car, and the minimum effect is an infinite distance in front of the car. So 10 meters ahead there is a very small wind favorable moving with the rider, but it’s still enough to produce that drag reduction.”
Kelso went on to quote Belgian professor Bert Blocken, who has done much of the little research on this topic, when he explained the advantages a following car at 10 meters would have on a cyclist.
“He found that, for a car following 10 meters, the drag reduction is about 0.23% on the drag coefficient, and that translates to 3.9 seconds over 50 kilometers. So for this 14 kilometer circuit is about a second.”
This second is therefore what the Pogačars and Dowsetts of the peloton would have potentially won at Lido di Camaiore. Although the “wall” of bikes above the following cars behind Ganna and Evenepoel will only have created an additional beneficial effect, Kelso said.
“With the bikes stacked on top, the vehicle actually looks more like a box truck, and in general terms it’s practically like having a double-height vehicle. If the bikes are tight enough and all the spaces between them are small enough, it will be a severe blockage of airflow.
“Basically, if you want the maximum effect, you’d want something with the aerodynamics and shape of a brick. A flat front, sharp edges, that sort of thing in order to maximize the drag of the following vehicle , because it will have the maximum effect on the air in front of us.” Kelso added, in response to the Israel-Premier Tech performance coach Greg Henderson’s joke that his team would use a team bus to track Dowsett in the future.
Kelso concluded that, for Ganna and Evenepoel, the effect of having their follower cars stacked with bikes would have likely given them a second of extra time over their rivals.
“I would double those times given all the motos on top,” Kelso said. “You look maybe a few seconds. That’s if the car is 10 meters behind the whole distance.
“I think it’s unlikely to have made a difference to those results, but of course nobody knows what the results will be until the race is over.”
Ineos and QuickStep’s idea then gave their runners a small advantage, and any time saved is a win, even if it didn’t necessarily change the outcome. Nonetheless, their ploy gave us all something else to look out for in future time trials.
In the short term, however, Evenepoel might be very grateful for that extra second at the end of Tirreno-Adriatico.
Ineos loves Ganna. In the time trial, they give him 10 bikes to choose from, in case he needs one in a different size. Or did the team car want to go for an early darts race?!? Nothing to do with aero at all. pic.twitter.com/knDi8EF2f5March 7, 2022
