First there’s the price: £425 for a plain colour, rising to as much as £600 for a pattern and more for a limited edition. The price may be a shock, but Ruby have elevated helmet design and manufacture beyond pure safety, and well beyond passing trends and fashion, to create a helmet that can be fetishised. On the surface, it’s a handsome, but optimistically priced open-face helmet, just like, on the surface, an Aston Martin V12 Vantage is a good-looking, two-door car. But hold a Ruby Pavillon in your hands, let it encase your head, and it becomes something different. It possesses the quality to convert sceptics. It converted this one.

Legendary Karl Lagerfeld and Ruby proprietor Jerome Coste get cosy

Ruby is the life and love of Frenchman Jérôme Coste. He is a Hendrix-esque, 38-year-old, brought up wedged between the front seats of a Jaguar XK120 by young, hippy parents. When we meet, Coste has Lewis Leathers boots on his feet, the keys to a Yamaha SR500 street tracker in his pocket, a silk scarf around his neck and a halo of aromatic smoke.

The Ruby Belvedere with 'Shibuya' design

Coste spent a decade and a half designing clothing and equipment aimed at X-Gamers, for American companies JT and One Industries. But by 2000 he had built up skate-, BMX-, Mountain Bike-wear company, Hold-Up. Then he ran it into the ground.

‘I thought I could do everything myself,’ Coste admits. ‘But I’m bad at managing the money stuff. Finally, I crashed the company.’

A collaboration with Japanese designer Kishimoto

Perhaps it because he’s talking in a second language, but I like the fact he uses moto-terminology to describe business practises. He didn’t go bankrupt, he crashed. And what do you do after a crash? If you’re any kind of man, you get back on.

In 2001, at a crossroads in his life, Coste started thinking about creating a helmet, ‘The most beautiful and best helmet in the world’. By 2003, the project became all-consuming. By then the name, the ridged crest and overall look was set.

The ridge. At first it appears to be an attempt to differentiate a Ruby helmet from every other lid on the planet. But, after some contemplation, the lateral crest echoes ancient warriors’ helmets. More recently, it’s seen on the protective headgear of First World War French soldiers, modern day firefighters and Darth Vadar. But the ridge is just the start of these helmets’ appeal.

‘Why Ruby?’ echoes Coste. ‘Because it is four letters. It is feminine in a world of sweating, dirty guys. It evokes descriptions like precious, hard, passion… It is also the name of the engine that powered my father’s Sandford, the three-wheeled racing car he competed in when I was a boy.’

Ruby watches over you from the Helmets' leather lining

Pick up one of the company’s helmets and Ruby stares back, with her fingers crossed, from the crown of the lining. ‘She is your guardian angel,’ Coste explains. ‘She is hot and she is looking after you. And every time you put on your helmet she is wishing you “Bon Voyage”.’

If you don’t believe in the protective abilities of this curvaceous 21st century St Christopher, the spec of the helmet is of more interest. The shell is completely carbon fibre, like the bodywork of Ferrari’s FI cars or the fairing of a MotoGP bike.

‘Riding in a city is more dangerous than on a racing track, so people in the city deserve the same as a champion.’

The lining is a mix of an Alcantara-like synthetic suede and French lambskin. The standard lining colour is Cardinal Red, ‘Inspired by the interiors of British sportscars,’ says Coste. The leather goggle retaining clip on the back of the helmet contains a card the wearer is encouraged to write his medical details on. The rivets that fix the two halves of the strap to the shell look like jewels. The whole helmet, even the box it arrives in, is of a quality than makes you just want pick it up and inspect it, put it on and only reluctantly remove it.

Ruby helmets are made in China, a fact that I find a little at odds with the price tag of the entry-level Pavillon, but China is home to the only factory that make carbon shells to the quality Coste demands.

The fur wrapped Karl Lagerfeld collaboration

The helmet itself transcends fashion, but Ruby has collaborated with Maison Martin Margiela to create a limited-edition, white-washed Ruby Pavillon that has the Margiela design team’s signatures and scribbles scratched into the thin top coat of paint. French artist Honet and Anglo-Japanese designers Eley Kishomoto have created other limited editions, but the next collaboration is likely to eclipse them all – in terms of coverage is not style. Karl Lagerfeld used mink- and white rabbit fur-covered Ruby helmets in his Autumn-Winter 2009-2010 catwalk show. This led to Ruby and Lagerfeld producing 100 Lagerfeld-designed fabric covered Pavillon’s for (fair weather) riders and a further six each of the fur-covered Belvedere open-face helmets for collectors. The PETA-baiting helmets will go on the market for up to €5000.

While I’d rather risk riding without protection than resort to a €5000 mink-covered crash helmet, the whole Ruby experience remind me of the adage, ‘if you have a €100 head, get a €100 helmet.’