Peter Ross: It might be a US icon but Scottish Harley-Davidson riders are devoted to their motorcycles

WILLIAM Corson, a 59-year-old shopkeeper from East Kilbride known as Big Willie C, laughs wryly and scratches his grey beard as he recalls his most embarrassing moment. There he was, riding through Perth on his beloved Harley-Davidson, at the head of around 70 brother bikers.

When they stopped at the lights, it felt like all the locals were looking at them in envy and awe. Suddenly, Big Willie recalls, his surround-sound speakers, which had been giving it laldy with Santana, started playing, at high volume, a song less acceptable in the grizzled, black leather world of Harley enthusiasts: Volare by Dean Martin. "There are times for such music, but that wasn't one of them."

Still, he concedes, it could have been worse. It could have been Tony Bennett.

We are talking in a beautiful spot on the fir-cloaked shores of Loch Goil in Argyll. The occasion is The Gathering, the annual rally of the Clyde Valley chapter of the Harley Owners Group. It is a grand day out, eagerly anticipated by hundreds of riders. "There's guys here couldn't sleep last night, they were that excited," Big Willie says.

On this scorching Friday lunchtime, the loch glitters in the sun, but its gleam is nothing compared with the polished chrome of the assembled motorcycles. Driving the serpentine B828, a hair-raising asphalt strip snaking between Beinn an Lochain and Ben Donich, I hear them before I see them. The engine noise is a deep dragonish growl you can feel in your stomach, so loud that it drowns out the birdsong and the burble of the burn, and seems to make the roadside bluebells blanch.

The bikes are quite a sight. The predominant colour is black. Some have tassels on the handlebars; others are decorated with spray-on flames or spider webs, silver skulls and fuel caps bearing the legend "Live to ride, ride to live". Harley culture is all about customising your bike, which they call hogs. The motorcycles cost between 7,000 and 30,000, depending on model, and it's common to spend more on modifications than on the vehicle itself. It's all about bling. One rider known as the Lone Ranger ("Because, eh, I spend a lot of time on my own") grins with pride while showing off his stand which is in the shape of a wolf's claw. An elderly golfer, passing on his way to the bar for a shandy, regards the bikes with wonder: "Have these guys never heard of the credit crunch?"

Though they look like Hell's Angels, and are given to corny macho outbursts – "Two things you never do: touch a man's drink and touch his bike" – the Harley riders, in conversation, can be as touchy-feely and as bitchy as models backstage at a fashion show.

"Is that what I think it is?" gasps Gordon Jamieson, 53, noticing a detail on the bike parked next to his.

"Aye," says his neighbour Dave Barclay, a 62-year-old in a black leather cap. "It's a cigarette lighter."

"That's brilliant. I want one of them," says Jamieson.

"And these," says Barclay, pointing to his handles, "are my heated grips."

But this is a comfort too far. "Heated grips?" Jamieson exclaims. "Ye big jessie!"

Harley-Davidsons went into production in 1903 and went on to become icons of rebellious youth, epitomised by Peter Fonda in Wild Angels and Easy Rider. These days, on the evidence of The Gathering, riders tend to be middle-aged and above. Among the youngest is Craig Ritchie, a 26-year-old from Hamilton in a Lynyrd Skynyrd T-shirt. He's here with his grandad Jim Connor, 76, the oldest man at the rally. Jim doesn't look his years. He looks like a pint of Guinness with his white hair and black leather. His wife Hilda, who is the same age, still rides pillion.

There are plenty of women here, though most came as passengers. One has diamante skulls on the frames of her specs. "There's not a lot of female riders," admits Nuala Mooney, 24, from Greenock. "It is a bit of a man's world." She just recently passed her test. Today she is "totally Harleyed up" and is even wearing earrings in the shape of the bike's logo. "My dad got a Harley when I was ten, and ever since then I've been obsessed," she says. "Learning to ride is probably the best thing that's ever happened to me. It's totally exhilarating. It's a total poser thing. I'm sure most people here would admit it. On a Harley you're not invisible."

Mooney's youth makes her an exception here. Harleys attract older people because they are expensive and relatively slow in comparison with your Hondas and BMWs. It's the bike you buy when your children have left home, when you've paid off the mortgage. Riding a Harley is what you do instead of golf or bingo or the bookies or the supped pint in the midday pub. It's a raging against the dying of the light. The patches on the back of the leather waistcoats say it all. "Sons of Arthritis" reads one. "Adventure Before Dementia" says another.

One couple in their forties, Martin McGorry and his wife Angela, bought a Harley using the money they'd saved for a new kitchen. "You could maybe say it was a midlife crisis," he smiles cheerfully. One man admits to buying his Harley, which he has named Precious, with a loan the bank thought would be spent on double-glazing. "I should really call the bike Everest."

Andy Taylor, a 62-year-old semi-retired plasterer from Stirling, is a small stocky guy with a white beard and hair and black leather trousers. His hog is black and cream. Strapped to the back he has a cuddly squirrel, a tough wee Tufty, holding a whisky miniature in one paw and a roll-up in its mouth. Taylor flies the saltire and lion rampant as he rides, and has been known to wear a kilt on the bike, though – as he puts it – "You don't go 'true Scotsman' if you want to avoid a draught."

He was into bikes as a young man, but gave them up in order to put food on the table for his family. These days he is a great-grandfather. "Unfortunately I lost my wife. I was going to end up just working and drinking. So I decided to get a bike instead. My grandkids think it's brilliant that grandad's got a Harley."

They are an amiable lot, these bikers. They even have a special Harley handshake – "We're like the Masons without the secrets," explains one – which consists of a regular handshake followed by a linking of thumbs.

They are by no means outlaws. "It's the establishment," says Alex Smith, a 58-year-old from East Kilbride. "There are as many doctors and dentists. I'm an engineer."

Martin McGorry is a big friendly giant from Bellshill, 44 years old with a shaved head and lager foam on his moustache. "What makes Harleys special?" he ponders. "It's the American dream. It's Marlon Brando. You're buying into a whole load of history. For me, it's a bike with a soul. It's got its own identity. I don't fully understand it. But it gives me goosepimples when I get on."

His Harley is a model called the Fat Bob, a name to bring joy to readers of The Broons. McGorry loves the bike. How fast it feels. The way it shakes so much your eyeballs vibrate. Mostly he loves the sound. "You want that big V-Twin thump. That's her heartbeat." The guttural throb of the V-Twin engine is sacred to Harley owners. It is their Agnus Dei, their Marseillaise. Pretty much the first modification anyone makes to a new bike is to change the exhaust pipes so the noise is louder. Not for nothing is the year's largest rally known as Thunder In The Glens.

Dez Urban, 52, comes from Glenrothes and is a member of the Edinburgh-based Dunedin chapter which puts on Thunder In The Glens. He's tall with a big belly, grey goatee and tattoos up his arms. He looks barry in a glengarry, and has had the front of his bike painted with a chrome ram's skull bursting through a St Andrew's Cross. Though Harley-Davidson is an American icon, many of the Scottish riders use the bikes and gear to express their patriotism. The Dunedin and Clyde Valley chapters have their own tartan. The club magazine of the Caledonia chapter, based in Stirling, is called the Fiery Cross after the symbol used to gather Highland clansmen for battle.

"Harley-Davidson is Scottish," says Urban. "The Davidson family came from up Arbroath way before emigrating to America. Of all the bikes in this country, Harleys are the only ones, as far as we are concerned, that should be on our roads."

That's a bit of a stretch, I think. Harley-Davidson is Scottish like Barack Obama is Irish. But the point is the ownership and kinship that these men feel for their bikes. It seems to be quite a profound relationship. Also a transforming one. Out on the hog, out on the road, you leave your humdrum identity in the slipstream and become Big Willie or Mad Dog or The Kraut, to choose just three biker names. It's a fantasy, a love affair. Dean Martin would have called it amore. But it goes even deeper than that.

"If her indoors ever said 'It's me or the bike,'" Andy Taylor laughs. "I'd ask where she wanted her claes dropped aff."