When you think of a trike, many ideas may pass through your mind. The trikes this entry is interested in are of the road-going kind - a kind of toy for grown-ups that come in many shapes, sizes and configurations to suit the varied tastes of the mild, meek and sometimes manic breed of human that owns them.

What is a Trike?

Well, the simple answer is a vehicle with three wheels. There, however, is where the common ground ends. Two main layouts exist: two wheels at the front and one at the back, or one wheel at the front with two at the back. The main concept all trikes have, though, is Fun with a capital F. If you haven't got a sense of humour, buy a Volvo...

The first layout was used in mass production in pre-war cyclecars such as the Morgan. The Morgan trikes used two front wheels with a front-mounted motorcycle engine driving the single rear wheel. This resulted in a light, agile sports car capable of embarrassing much larger machinery.

In the 1950s, the layout was adopted in the bubblecar world with the Messerschmitt, Trojan and BMW Isetta providing frugal transport for a frugal world. Engines were based on scooter units mounted on a swingarm. In the 1980s and '90s, the layout became extremely popular in the kit-car industry with a wealth of traditional and modern designs being created, all based on the Morgan's principle of a cheap, lightweight sports car. Notable designs include:

• The JZR trike is an unashamed copy of the Morgan using Honda or Motoguzzi motorcycle engines.

• The Lomax range of trikes all using Citroën 2CV running gear - the flat twin engine, front wheel drive and fantastic suspension of the Citroën harmonising perfectly with the three-wheel layout.

• The modern Grinnal Scorpion trike using BMW motorcycle parts - a rear engine, rear drive machine bringing sports bike style and BMW quality in a machine guaranteed to make your mates jealous!

There are many more of this genre, and the above list only skims the surface to give a rough idea of what's out there. Indeed, there are many more that enthusiasts have scratch-built at home to their own designs - are you sure you've never parked next to one at the supermarket?

The second layout will be far more familiar - do you remember Del-boy's van from the British TV Comedy series Only Fools and Horses? By far the most familiar layout is the one with the single wheel at the front and two wheels at the rear - undoubtedly made notorious by Reliant's Robin. Although many preceded them, the mass-produced Reliants were by far the most popular trikes, succeeding by creating a niche market targeting motorcyclists who wanted creature comforts on the cheap. They are literally a small car with a single wheel at the front. Remarkable, rollable, and very much ridiculed...

However, in the kit-car and home-built specials arena, other things were, and still are, afoot. Taking the idea of a motorcycle front end with two fat wheels at the back, leagues of customizers have created trikes to scare your granny with. Front-engined, rear-engined, car-engined or motorcycle-engined, this layout has spawned a sub-culture all of its own. A popular idea is to use the rear engine/transmission/suspension assembly from a VW Beetle, coupled up to a low-rider frame and long, long forks which results in a well-handling trike of good proportions. Most are home-built (see www.triker.com) - the simplicity of the design being ideal, although Germany's Boom Trikes Ltd produce brand new ones for around £10,000 sterling. Others stem from motorcycles fitted with a car rear-axle, or even other car-based combinations.

Notably, anyone considering a motorcycle/sidecar combination would be wise to consider a trike instead. The layout of a trike is symmetrical and is thus a far more stable alternative. More importantly, they allow disabled motorcyclists to carry on pursuing the lifestyle they love. This, in this Researcher's opinion, is the most outstanding benefit the design offers - making it the ultimate symbol of freedom.