Polished metal glints through tall hedgerows as you approach Cake Street Classics, a garage and homestead surrounded by flat fields near Laxfield, in the heart of rural Suffolk. From here, a British bike still with Ohio number plates may be shipped to Oslo, Munich or even Reykjavik.
Recently, encouraged by the strength of the pound, especially against other European currencies, British bike enthusiasts have been buying the lion's share of vintage bikes on offer - and pushing prices up as well. Two years ago, Mr Sharman - a 49-year-old former biker - was exporting 60 per cent of his stock to Europe. Now, the Brits are taking 90 per cent.
His own cherished 1960 BSA Spitfire street scrambler, one of only 1,200 made, was discovered in a barn in New Jersey and is now resplendent following the four-week restoration he lavished upon it. Such a bike would have been bought in the US as a fun runaround. Almost as a toy. Nowadays, almost all American collectors are after only their native Harley Davidsons and Japanese models.
In the British and European collectors' market, the Spitfire would have been worth pounds 5,000 two years ago and pounds 7,000 a year ago. Today, he would be looking for pounds 8,500. If he was selling, that is.
It's nostalgia that drives the British market, he reckons. That means bikes of the Sixties and early Seventies are most in demand. Daredevils who raced them from cafe to cafe on main roads are now approaching middle age. Mr Sharman says: "Their children are off their hands and they have paid off their mortgage. As soon as they get on a motorbike they feel 10 years younger. That's an investment in itself".
And get on them they do. A customer telephoned while I was there, asking for a BSA M21. That is a mid-Fifties sidecar model that has acquired a big following. It means the wife can stop complaining and join the fun. M21s are not rare. They cost about pounds 2,500.
The Scandinavians take to the roads even more readily than the Brits. The Japanese - who are now less able to afford bikes but are no doubt saving up their low-value yen - tend to hoard theirs, museum style.
What of the 1929 500cc Rudge Whitworth with flat handlebars leaning against the garage door? Not much nostalgia value, surely, now that almost all its riders have died of old age. "Not at all," said Mr Sharman, "you should see those old boys hit 125mph on the standard quarter mile. I know one who has a Rudge that can go as fast as a 1100cc Suzuki of the late Eighties." Tell that to your grandchildren.
An advantage of bikes compared with vintage cars is that they are smaller and easier to store. You can garage them in the garden shed. "Ideal for the average man," says Mr Sharman. But being treated as an "average man" can still come as a shock to respectable middle-aged bikers. My supervisor at university, a fiftysomething whose biking horrified his family, once screeched to a halt outside the Randolph Hotel in Oxford, where the doorman waved him away, shouting "You can't park that 'ere". Raising his visor, the ageing biker said in his gentlemanly way: "I believe a room has been booked." The result was effusive apologies.
In recent years, at the Plough Inn, not far from Cake Street, a group of born-again bikers who had been refused service at lunchtime upon sight of their leather jackets, booked dinner there by telephone, turned up in normal street wear, then walked out of the restaurant in protest, as soon as the meal was served.
There must be politer - and legal - ways of keeping up the ends of wrinkly bikers. Fortunately, each make of bike has an enthusiasts' club. They have a reputation for friendliness and helpful advice - for instance, about where to find spares.
Mr Sharman has 20 tons of spares. He can mend practically anything with wheels. He used to restore horse-drawn vehicles. Then he hired out JCB diggers. The motorbikes are a hobby of his that got out of hand, four years ago, and turned into a full-time profession.
We walked down an avenue of 40 bikes to where a 600cc Norton stood. The frame and engine were late Fifties but the bike had been customised in 1972, "Easy Rider" style, with apehanger handlebars, high-rise seat and a diamond-shaped petrol tank. Not a lot of demand for such a poor man's Harley, though the Germans have been buying them. Whoever customised it would probably have paid only pounds 100 for the basic machine. Mr Sharman was offering it at pounds 1,200.
A better investment, he said, would be a BSA 500cc Gold Star, the ultimate caf racer of the Sixties, capable of 80mph in first gear. Their price, pounds 6,000-pounds 9,000, has been stable for the past five years or more. Soon, he thinks, prices should be putting a spurt on.
A Manx Norton, designed for the TT races, could cost you pounds 18,000. But it is middle-range prices that are rising fastest. BSA, Triumph, and Norton are all solid names to invest in - though Norton spares are rather expensive.
Are motorbikes as dangerous as they are made out? I was determined not to even mount one. Instead, I stumbled and cracked a rib on the pedal of a parked 1941 Matchless. Those old bikes certainly pack a punch. Even when standing still.
Cake Street Classics: 01986-798504.Reuse content