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Stubby vs. long tail aero helmets - which is faster?

A sprinter prepares to race at Six Day London
Sam Larner
16 Dec 2015

The question over stubby or long tail helmets continues to drag on but, in the confines of a velodrome, why is there still a debate?

Time trial helmets reduce drag significantly versus a normal non-aero helmet, of that there is no question. The traditional long tailed helmet when worn flat, merges into the back so air flows over the helmet and only creates turbulence once it’s left the body. Unfortunately, the benefits are only clear when worn in a wind tunnel by someone with a perfect body position.

Once you’re on the open road in crosswinds, and fatigue is contorting your head away from the ideal position, the benefits are far less obvious. This is why many companies now offer ‘stubby’ versions of their aero helmets. These aim to provide a middle ground by creating a smooth airflow, like the long tailed helmets, but without creating huge drag when the rider’s head is down. So, the benefits of an aero helmet on the road are not as straightforward as you think. To see improved performance from an aero helmet you need to reduce as many external factors as you can.

Lazer guided

Bradley Wiggins Hour Record Olympic Velodrome - Jordan Gibbons

Cyclist spoke to the R&D team at Lazer to find out why long tailed helmets aren’t ubiquitous even on the smooth wood of a velodrome.

‘The basics are that for a 4km pursuit, based on a ‘flat back’ position the long tailed helmet is a more aerodynamic choice. A rider should be able to keep their head in the optimal position for a race of this distance.’

That seems straightforward: short races mean you opt for a longer tail on your helmet. Not all teams are adhering to this rule though - in the World Championship men’s team pursuit New Zealand and Great Britain wore teardrop helmets but the bronze medal team, Germany, went for helmets with no tail. Casco were the manufacturers of these helmets and its explanation is that the negative aerodynamics caused by imperfect head position exist even in short races.

‘We believe that no athletes, even professionals, are able to remain in ideal position. Especially not in the heat of the race.’

It says that even a stubby helmet creates drag when lifted and the only way to avoid this is to use a helmet with no tail.

Rob Lewis, CEO of TotalSim, who has previously worked with British Cycling sits somewhere between the two: ‘Even in longer races, the riders spend the vast majority of the time facing forwards. As soon as they deviate there’s an aerodynamic penalty, but it’s gradual. It’s like alcohol consumption; each unit is doing a little more damage.’

Short and sharp

Track time trial at the Six Day London

So what about shorter races like the kilo? Yet more confusion here. Two of the podium finishers wore helmets with no tail and only one wore a teardrop, it was the same story in the women’s 500m TT too.

‘A sprinter’s head often looks down as they ‘lay down the power’ on the track, thus meaning they don’t want to have a sail slowing them,’ says Lazer. It’s a similar story too from Casco.

Casco’s Warp helmet was first worn in the 2004 Olympics to gold medal success. ‘The helmet is aerodynamically neutral for all head movements by the sprinter. The Warp is enormously manoeuvrable without any aerodynamic disadvantages due to its compact shape,’ says Casco.

on the open road a long tailed helmet is of negligible benefit or potentially a disadvantage

Lewis doesn’t agree that helmets with no tail are aerodynamically superior.

‘Because they’re not completely spherical, there is an aero disadvantage to turning them without the performance benefit when you face straight on.’

He’s also not convinced by the explanation that when riders face down at the beginning of a kilo long tailed helmets are a huge disadvantage.

Laurent Fignon time trial at the Tour de France

‘You’ve got to remember that drag increases as a square of velocity, so when the speed doubles the drag quadruples. The drag won’t be a problem at the beginning of a race at low speeds.’

Tell it to me straight

So what’s the advice? If you race entirely in a wind tunnel with the head positioning of Bradley Wiggins then you should go for the longest of long tailed helmets. Realistically, if you’re riding on the open road in a time trial of any length then a long tailed helmet is of negligible benefit or potentially a disadvantage. 

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