As I rode under a dark grey storm along the narrow roads of Buckinghamshire, large pellets of rain splattered down relentlessly, gathering in my lap. This wet, gloomy weather is far from the biker's dream of big, blue skies and empty highways. But that hasn't stopped British bikemaker Triumph from aiming squarely at the American biking idyll with its latest cruiser, the Thunderbird.

It is a confident but risky move: in reaching for the cruiser market, Triumph has had to play by the rules that have put Harley-Davidson in the leading spot and kept it there.

Cruisers are long and low; they have flat or high handlebars. They have forward foot-pegs and little cornering clearance. These defining characteristics describe a traditional Harley – but they also sum up what many buyers expect of any motorcycle. Just as most car drivers would regard with great suspicion any vehicle that did not have four wheels, most cruiser riders would not look favourably on a bike without these classic features.

Triumph already has cruisers in its range. The Rocket III, for example, with its 2,300cc engine, outdoes most in the big and wide stakes. But the Thunderbird is aimed at the traditional middle sector, an area in which it has not yet pitched a contender.

Harley has been hit by the recession, so this is a good moment to strike. Such is Triumph's bravado, it even boasts of plans to be the second-biggest seller of cruisers within 10 years. So it has been assiduous in following the rules, and the Thunderbird has all the styling that buyers of these motorcycles demand.

But where Japanese bike makers have also aped Harleys by using V-twin motors, Triumph has given itself a unique selling point with a parallel twin engine. This layout harks back to Triumph's 1950s and 1960s heyday, but it has been cleverly modernised by giving the engine an architecture that makes it sound very similar to a V-twin. Ignition of the two cylinders is 270 degrees apart, which means that the bike has the offbeat exhaust rumble familiar to all cruiser riders.

At 1,597cc, or 98 cubic inches, the engine can supply enough grunt to move the rather portly motorcycle surprisingly quickly. And, operating through a six-speed gearbox in which top gear is an overdrive, and a belt rather than chain final drive, it delivers a smooth and sophisticated ride.

Which is slightly more than can be said for the chassis. It is accomplished enough, so that it feels safe, but gives a rather remote feeling from the wheels. Especially when using the powerful brakes.

And then there is the riding position. Bombarded by raindrops, I felt as if function had lost out completely to style. With arms and legs out, even 70mph is not comfortable for any length of time. And that riding position made it impossible to avoid my spine being jarred as the bike tried manfully but failed to iron out moon-crater-sized Buckinghamshire potholes.

When I first saw the pillion accommodation that I would be asking the Professor, my partner, to use, my heart sank lower than the height of the rider's seat. However, after an admittedly short ride she was favourably impressed. While the rear seat is tiny, it has enough padding that the Professor pronounced it better than any Harley she has sampled.

Triumph does, however, offer more comfortable seats, and a range of alternative parts. As the company points out, Harley buyers tend to spend about £2,000 on accessories. Buyers of Triumph's own Rocket III tend to spend upwards of £1,500. More than 1,000 accessories designed alongside the bike are already on offer from Triumph, including a big bore kit which takes the engine up to 1,700cc, with a commensurate increase in power and, of course, grunt.