BMW R1200

The bike that took Ewan McGregor around the world is now even better

Engine: 1170cc air-cooled flat twin
Maximum power: 100bhp @ 7,000rpm
Maximum torque: 115Nm @ 5,500rpm
Transmission: six-speed gearbox, shaft final drive
Brakes: front dual 305mm discs, rear 265mm disc.
Weight: 223kg
Tank capacity: 33l
Price: £9,755

In the spring of 1938, Republican troops fought heroically in the Sierra de Javalambre, north-west of Valencia. Spanish fascist forces and their Italian backers deployed 1,000 field guns against Republican lines. The Nazi Condor Legion bombarded them from the air.

But the mountainous terrain proved a faithful servant of democracy. From trenches amid the rocks and trees, Republican soldiers laid down fields of fire that cut down 20,000 nationalist aggressors. Even Franco's notorious Moorish regulars were intimidated.

As I faced the wooded rock-strewn slopes above Aras de los Olmos on the new BMW R1200 GS Adventure, so was I - very. Motorcycling up rutted trails cut through forests and into the edge of cliffs is demanding at the best of times. Doing it in the rain, with limited visibility, is harder. Add mud like porridge, fallen trees and angry wild boar, and this is as serious as off-road touring gets. But the six-times Paris-Dakar competitor Simon Pavey was taking it all in his stride, and my choices were limited. I could follow him or get lost. I followed - and it was great.

The R1200 GS Adventure is an upgrade of the 1,150cc machine on which Ewan McGregor and Charley Boorman completed their Long Way Round odyssey. The original is a tremendous motorcycle. This one is 15 per cent more powerful. It generates 17 per cent more torque and, despite the larger engine capacity, it is fractionally lighter. Add a gigantic 33-litre fuel tank offering a potential range of 450 miles and you have a very serious piece of kit.

Off-road, this is the closest motorcycling has come to an armoured personnel carrier. With knobbly tyres, it will climb every mountain and ford every stream. Pavey boldly demonstrated its prowess by riding it up a steep, boulder-strewn mountain fire-break. The only limitation on its capacity to go anywhere is rider ability. Pavey could probably get it up Everest. It is so user-friendly that I would be tempted to follow him.

This is not a trials bike. If you want to tear around in the dirt at high speed, buy something lighter. The Adventure is a heavy-duty off-road tourer. It ploughs through sand, thrusts mud contemptuously aside and spits out lumps of rock as though they are orange pips. No matter how rutted, steep or crumbling the obstacle, it will get a competent off-road rider through. The torque is awesome - pulling from virtual standstill in second and so facilitating the extreme close control necessary for demanding conditions.

A new screen gives improved weather protection. The seat is height-adjustable. Protection bars keep the big boxer engine safe from the spills that are almost inevitable in demanding off-road treks (I stayed on). Extra-wide footrests and adjustable gearshift and brake-lever make it plain it is meant to be ridden standing up. The Adventure is the definitive motorcycle for riding across wild continents with a partner on the pillion and camping equipment lashed to the rack.

That promise of excitement has already established the GS range as BMW Motorrad's big success in the UK. The R1200 GS Adventure is superb, fully justifying pre-launch predictions that it will replace the R1150 version as the ultimate long-distance enduro machine.

Just one warning. To enjoy it properly you need to spend a lot of time far beyond the place where the asphalt stops. The R1200GS is rugged and durable. Cutting down a lava field or up a stream, it is thrilling. There's no motorcycle I would rather ride across Siberia. This is a serious piece of technology, not a city-centre posing platform.

On the tarmac, it becomes merely very competent. Plenty of motorcycles are better on motorways, and many are easier to lace through urban traffic. The Adventure's high riding position enhances forward visibility - but it is too broad for advanced filtering and too heavy for urban stop-start (especially with a full tank). Shod with off-road tyres, it rides like a tractor on tarmac. Of course, you can fit it with road tyres and use it to commute. But that would be sacrilege.

That said, it looks fantastically rugged, and I can imagine the temptation to speckle it with mud and ride it down the King's Road. A motorcycle this good deserves to be used properly but it will acquire cult status and lots of buyers will not even get theirs dirty. I wish I could afford such self-indulgence. Ah well. With luck there will be several unmarked second-hand versions available next year.