Modern all-terrain motorbikes offer unlimited adventure. But before you tackle the Dakar rally you'll need to master a few basics; like not falling off. Andrew Spooner visits a school for not-so-easy riders

Normally, a slip in such conditions is a minor irritant. You get slightly mucky and your pride hurts. If only it was as simple as that today; I am pinned under almost a quarter of a ton of R1200GS BMW motorcycle in a puddle of filthy brown water.

This is my first morning at BMW's Off Road Skills Course, at the training centre on the edge of the Brecon Beacons in South Wales used by Ewan McGregor and Charley Boorman to prepare for their Long Way Round global motorcycle esca-pade. As I try to wrench my foot clear I realise it is stuck behind a foot peg. I swear, cuss and spit.

One week earlier, things had been very different. I had been riding the dry, gritty trails of Aras, just outside Valencia in Spain. Perched on top of my R1200GS Adventure, BMW's latest addition to their fleet of go-anywhere motorcycles, I felt invulnerable. This was my first time on a motorcycle over 1,000cc, and its power, durability and superior handling were obvious even to an amateur like me.

"This is a superb motor-cycle," said Simon Pavey, the 38-year-old Australian who founded the Brecon Beacons course. I watched in awe as Pavey, a Dakar rally racer, pirouetted the bike over various obstacles. He made it look so easy.

Back in Wales, after spending 10 minutes scraping a small trench with my foot I manage to make enough room to free my leg. I stand up, drenched, annoyed and with an urge to give my motorcycle a hefty kick. Instead, I gather my thoughts and energies for my next task - lifting the thing up. All 495lb of it.

"How to pick the bike up is the first thing we teach you on this course," said my instructor, Jonty, earlier that day, as he laid his R1200GS in the mud. The gathering of willing students, all male, mostly middle-aged and wearing suitably musty leathers, looked on incredulously. Fortunately for them, most had chosen to ride the much lighter and more mobile BMW F650GS. "You'll be spending a lot of time picking up your bike over the next couple of days," Jonty continued, "and, once you know the technique, it's pretty easy."

As Jonty turned the handlebars sideways, jutting the front wheel into the air, he cradled them in a strong grip, and began pushing from his knees, lifting the heavy motorcycle upright. I did the maths; the R1200GS was three times my body weight - would it be possible? "Now it's your turn," said Jonty.

Hours later, standing beside my puddle, I am grateful for my earlier lesson. I manoeuvre the BMW to a vertical position, start the engine and gently power it up the small slope that had been my downfall. With armoured jacket and trousers giving me protection on hips, knees, elbows, back and shoulders, I have been left physically unscathed. I am shaken, though, as I head to the warm hospitality vehicle.

Two-wheeled transport is undergoing something of a renaissance. With road congestion, burgeoning parking charges and the threat of terror attacks on public transport, motorcycle sales have increased dramatically. In addition, the Department of Transport recently released a report encouraging local authorities to make life easier for motorcyclists. It's official - bikers are respectable.

The R1200GS is now the biggest-selling bike over 1,000cc in the UK. Recently returned bikers - the fastest growing group of motorcyclists are 35-plus - are getting out their chequebooks in droves, prepared to fork out the £9,755 required.

Many of them will rarely go beyond the local ring road, and some would argue that the R1200GS is far too big and cumbersome to be taken seriously as an off-road bike. Most motorcycles used for off-roading are incredibly light, with engines as small as 250cc.

But at the beginning of the course I feel on top of my game. "We are going to practice slow-speed control," says Jonty, after we have completed the picking-up workout. "You need to stand up on the foot pegs and balance your weight over the centre of the bike, using it to help you turn."

I swing the hefty bike through an arc of cones set in thick, greasy mud. Then comes a series of braking exercises - locking the back and front wheels in dramatic skids across the dirt. I am beginning to enjoy myself. "Let's go for a trail ride," says Jonty.

It is at this point that things start to fall apart. The combination of fierce wind, driving rain, bone-breaking rocks and slithery mud slowly whittles away my fragile confidence. By the time we reach the engine braking exercise at the top of a steep, boulder-strewn slope - "We want you to go down here without using your brakes" - all self-confidence has deserted me. Twenty minutes later and I am under the bike in that puddle. Oh well - there's always tomorrow.

The next day Pavey puts me with my own instructor to help me rebuild my confidence. "Just take things easy, try and enjoy yourself," he says as he introduces me to Tony Woodhams. A cheery 51-year-old Londoner and erstwhile project manager working with young offenders, Woodhams should have the experience and patience to get me through.

"Let's retry the engine braking," he says as we set out. "Don't worry, it's on a much gentler slope." I complete this task and we begin a series of restrained trail rides. "The conditions are about the worst I've ever seen them," says Woodhams when we stop for tea.

As the day passes I can slowly feel my confidence returning. "These are big bikes that are difficult to ride in such conditions. But at least you know you can take them anywhere," says Woodhams.

I complete my day with a Level One pass certificate in my hand, and arrive back at my Brecon guesthouse wondering if it was worth the effort. The next day, with the clouds clearing to reveal bright spring sunshine, I anxiously climb on the R1200GS for the ride back to London.

After two days in the muck I cruise through the beautiful Welsh mountains without incident. I've been on a pretty steep learning curve, yet have got through in one piece - just. While my off-road confidence is, at best, shaky, my on-road confidence has blossomed, and I arrive home with the broadest grin on my face.

A two-day, Level One BMW Off Road Skills Course costs from £360. Details: 0800 0131 282,

For your local dealer: 0800 777 155,