The seating position is aggressively bum up and foot back, ready for down and dirty cornering. The deliberately exposed tubular frame declares stripped-down racing pedigree. Minimalist instrument housing; short, sharp drop-down handlebars and chunky inverted front shock absorbers all add to a first impression of a bike that means business.

The Street Rod is the latest incarnation of Harley's VRSC (V-Twin Racing Street Custom) line, launched in 2002 to bridge the gap between the angry sport bikes of other manufacturers and the lazy cruiser that Harley is often seen to epitomise. They suggest that you call this new machine a roadster.

Another gap Harley had in mind with the VRSC was the rapidly shrinking one between its bed-rock baby-boomer market and their impending demise. This is a younger, faster, meaner Harley, bred to conquer demanding new markets.

You have to admire the Harley-Davidson Motor Company for its ability to reinvent itself. After decades of success built on military sales during and between the two world wars, the company almost sank beneath the onslaught of Japanese manufacturers during the 1970s.

It was reborn after a management buyout in 1981, and marketed itself to the wealthy middle-aged of America. As one Harley executive famously put it: 'We sell the ability for a 43-year-old accountant to dress in black leather, drive through towns, and have people be afraid of him.'

The Street Rod represents another carefully calculated repositioning, and breaks the mould on several fronts. Harley's styling department spent six years coming up with the new look, which required several innovations. The petrol tank, for example, is housed beneath the seat. What appears to be the tank is in reality stuffed with electronics.

While they were busy, a team of Harley's Kansas City engineers took up residence at Porsche's Weissach engine development centre.

The Street Rod's explosive 120bhp 1130cc Revolution V-Twin engine is the happy result of that collaboration. It is the first Harley power train to lead with a radiator ('the hot-blooded, liquid-cooled branch of the family tree', says the brochure), and to counter-balance its output it comes with the most advanced brakes fitted to a standard Hog.

I had forgotten just how cumbersome a large bike not yet under steam can be, and I battle to lumber the idling 280kg beast into the traffic. Then the light changes, I release the clutch, and we are transformed. The chains of gravity and friction fall away, and I am gliding towards the promise of that mythical Route 66 sunset.

If this were my bike, the first thing to go would be the ridiculously stubby rear view mirrors, which in the interests of aesthetics are mounted far too narrowly to provide a decent view of the road behind. In traffic like this they are untenable, and I nearly sideswipe an idiot in a Porsche as he weaves past me in the left-hand lane.

Plodding in tight traffic towards the highway, the engine responds well at low rpm, hardly seeming to notice the clutch, and this together with the quiet pipes makes it easy to forget to change gear, either up or down.

But out on the open road, it is the bike's snappy high-gear acceleration that is really striking. Taking advantage of a relatively empty stretch of the Eastern Highway, I test its limits by alternately throwing the throttle wide open in fourth gear and then stomping hard on the powerful brakes.

As the bike's full horses kick violently in and out, I must look to anyone watching like a rookie cowboy trying to hang on to a demented bronco. But despite my childish behaviour the bike refuses to wobble or veer, the brakes remain rock solid and the engine doesn't miss an opportunity to surge forward. Impressive.

Everybody should ride a really top-class road bike at least once in their lives. Some may not take to it, but surely none will ever forget the incredibly exhilarating sensation of low flying, of blatantly excessive power at your fingertips, of arrogant superiority to the hoi polloi trapped in their four-wheeled straitjackets and yes, dare I say it, of freedom and space. This is the perfect antidote to an overdose of Hong Kong claustrophobia. The bike is only mine for an hour, but I will be wearing a little smile for the rest of the day.

Harley is particularly proud of the good reviews it has received of the new Street Rod's much-improved handling, and I take to the tight, winding roads of Tai Hang to try it out. I have no intention of attempting to approach the bike's stated 40-degree lean angle here, but dropped into bumpy, uneven corners at low speed it feels rigidly trustworthy and capable.

All too soon, it is time to turn back to the showroom. The only part of me not complaining as I drop the stand and park is my left wrist, which by now is almost numb from arm-wrestling the hard hydraulic clutch, which would take some acclimatising. The seat, too, would perhaps wear a bit thin after a full day in the saddle. But then that would be a small price to pay for getting better acquainted with this thrilling machine.