Every major company can point at a product that, to a major extent, either saved them from corporate disaster or catapulted them to global domination. Apple with the iMac. Sony with the Walkman. IBM with the PC. Apple again with the iPod. And again with the iPhone. BMW with the GS.

It may be a slight exaggeration to say that before a couple of actors got on a brace of GS's and rode around the world, BMW was looked at as the sensible - boring even - choice if you wanted two wheels. Afficionados knew, of course, of the hairy and slightly insane folks who took large and inappropriate looking bikes at vast speeds across the Sahara, frequently riding flat out for hours with broken ankles and carrying out various other feats of heroism. And some of us were used to seeing the occasional GS doing things which might raise eyebrows.

A very long time ago I had an 1100GS on loan when my normal bike stopped working. Inconveniently I was supposed to be going on a trackday, so I ended up taking the GS. It was hilarious, far better than it should have been, and managed to irritate a large number of sportsbike riders by being surprisingly fast and handling well enough to scrape the cylinder heads.

But that wasn't going to change BMW's position in the marketplace. No, that would need the attention of a couple of mad keen biking actors, a film crew, a massive budget from the BBC and some really good production. The result was a TV show about a bike journey - about the bikes, in fact - that, against all the odds, massively captured the public's imagination.

And suddenly BMW had a hit on their hands. The GS went from being a mildly eccentric choice to the two wheeled equivalent of a Range Rover. And as time moved on, like the Range Rover the range grew. And grew. And sold by the shedload.

To put things into perspective, there are roughly 21,000 1200 and 1250 GSs in use in the UK. Compare that to the real workhorse that started off as the sportsbike everyone raved about - the CBR600. For a long time you couldn't move without falling over the ubiquitous Honda, and today there are still just under 15,000 on the road here. That's going right back to 1991 and counting bikes sold today. There are 50% more of the big ugly BMW on the road, and that translates to one heck of a lot of sales.

So what on earth do people see in the GS? It's big. Properly big. And the Adventure version is colossal. It's got looks only its mother could love, though the current incarnation tested here is somewhat less aesthetically challenged. It's heavy. While some versions have proper off-road credentials, with knobblies and massive suspension travel, there's no doubt that something with that weight and size would be a proper handful on the loose stuff. And it's wide. Which makes filtering through traffic on that morning commute a little more challenging than may be welcome. And yet, for some strange reason, people can't get enough of them. Time for some objective testing then.

Approaching the GS for the first time it becomes apparent that BMW build quality is still pretty darn good. The thing oozes quality. Take a run-up and swing your leg over the seat, and you'll be rewarded by a nice settling of the machine and the surprising result of being able to get at least one foot flat on the floor. This particular bike has the ridiculously clever adaptive suspension, which wouldn't surprise me if it "knelt" when at a standstill. Actually, if it doesn't that would be a bloody good idea. Anyway. Once on board, while there's still no denying that you're sat on a very large machine, everything comes to hand quite easily. Switchgear is mercifully conventional though there is a lot of it on this version (it's got lots of toys) and the full colour TFT dash is bright and clear. The screen is easily adjustable and the mirrors are clear and well positioned. The seat is also spectacularly comfortable. So far so good.

Hit the starter and there is a lurch to one side as the mighty boxer twin fires up. Once running the tickover is a pleasant, slightly offbeat rhythm that feels very natural. It's quiet, but not stifled. The clutch is light and the gearshift is positive. Pulling away is utterly free of drama, other than the very disconcerting magic trick that the GS plays as it sheds weight and size as soon as you get moving properly.

I have to do a lot of riding in traffic, and though this time I didn't have to go through the middle of London I did have a fair chunk of filtering as I negotiated the M25 (that's the motorway around London for non-UK readers) during the rush hour. And the next surprise was that after a bit of acclimatisation I found it surprisingly easy to dribble along at walking speed without my backside getting cramp or pulling off the seat cover. I wasn't about to start taking liberties because something this size will gain momentum awfully quickly if it decides to fall over or go in a direction other than that I intended, but with that caveat it was still a very easy experience.

Then it was the open road. Now this isn't a sportsbike, and trying to ride it like one ought to end in tears. And yet the degree of progress that you can make is staggering. It's a genuinely quick bike and the handling is a revelation. Having the Telelever front end means that there's a single shock and the geometry has the strange effect of almost eliminating dive under braking. Which means that you can take massive liberties with the brakes (bearing in mind the manual expressly tells you that you can't overcome physics) and know that the ABS will stop it from locking up and the Telelever will stop it from getting out of shape too much. At the back the Paralever handles both being the shaft drive housing and being the only side of the swingarm still present. It doesn't seem to have any real effect on handling except looking very trick and saving the weight of half a swingarm. On this version the suspension is adaptive, with selectable rider modes and the ability to fine tune it (or, indeed, mess it up completely) yourself. That puts a brain in the bike which makes more decisions, faster and more accurately in a second than you could in a couple of minutes of looking at the situation and trying to decide what to do. It will adjust rebound, compression and spring rate instantly according what's going on. About 10,000 times a second. The ride is pretty bloody impressive as a result. And the real beauty of a system like this is that, while you can make lots of adjustments yourself to reach what you see as perfection, you actually don't need to. The bike will adjust for your weight, and all you need to do is select one of the presets to get the best possible setup for you. Now.

While mechanically the GS can trace its roots easily back to the (in)famous Afrika Korps style combinations beloved of Hollywood war films producers, the current incarnation is rather more sophisticated under the skin. Though if asked it would probably still run on two star. In fact, joking aside, I believe that you can actually set it to accomodate very low octane fuel as encountered in some likely Grand Tour destinations. Or perhaps it does that automatically as well, I'm not sure. And I can't find it inthe manual. But I digress. This latest version of the vernerable boxer engine has something called Shiftcam. The inlet camshaft (it has two overhead cams per cylinder) has two cam lobes per valve next to each other. One gives maximum valve lift for peak power, the other a reduced lift for economy and mid range flexibility. According to the throttle opening the cam moves, bringing the different lobes into play as needed. It's bloody clever, utterly seamless in use and makes the engine - already known for being flexible anyway - even more elastic in its power delivery. The gearbox, too, has improved beyonf recognition and now shifts up and down like a knife through butter. This particular model has the added blessing of Shift Assist Pro, which is a quickshifter to you and me, but the lever action is delightful even without that. Add a fly by wire throttle and sophisticated fuel injection and you get a responsive, flexible powertrain that still has a decent dollop of character. Oh, and the elctronics package, while it may seem a little OTT for a bike like this, really adds vast amounts of confidence. The traction control works like a charm while remaining unobtrusive, and believe ot or not the anti-wheelie function does come in useful as well. Because yes, this behemoth will still lift the front given a decent handful.

Ergonomically the GS is difficult to fault. The screen, though tiny, works well and is adjustable to cope for taller or shorter riders. The seat is comfortable. All day comfortable. You can also specify a lowered version (in fact this one is lowered) which benefits people smaller than the Cerne Giant. The switchgear is easy to use and reasonably logically laid out, the mirrors are easy to see and work well. They are also high enough to go over car mirrors when filtering, though that does mean they sometimes get caught out by vans instead. Though the wide tank looks as though it should feel like riding a shire horse, in fact your knees are still in a very natural poition, while the position of the pegs ensures that you have room to stretch a bit as well. The headlight is powerful and well focussed, as you'd expect. Given the huge tank and the backside-cossetting seat, along with the effective screen, it should come as no surprise to learn that the GS is phenomenally good at covering miles. In fact, it would make, in my opinion, at least as good a choice of weapon for a long distance excursion as anything else currently available. Mainly because after arriving in comfort you'd still have something spirited enough to have a decent bit of fun with.

It's not all perfection, of course. Fuel consumption is quite heavy at first glance, low speed riding is, in spite of my comments earlier, still a far from relaxing experience and if it was particularly windy or you found yourself coming to a halt on a steeply cambered road then I suspect things could get quite tense quite quickly. Though the GS does have some obvious off-road pedigree, as it ships I'd be reluctant to take on anything tougher than some gentle green laning. As much as anything because it's a big heavy bike which will take an awful lot of stopping in the event of an unexpected development like, say, running out of grip or traction. Or both. It also doesn't really have the right tyres for serious off-roading, though of course you could opt for the Adventure version with the bigger front wheel, more suspension travel and proper knobblies if you're serious about getting dirty. Think of the GS more like a Range Rover Evoque - you could drive it across a muddy(ish) field or along a farm track but you're hardly going to tackle the Paris-Dakar in it. Going back to the fuel consumption, I say it's heavy at first glance.The reason for the qualifier is that, in fact, the reason it was heavy is because I was spending an inordinate amount of time with the throttle wide open. Not because the bike needed a big handful to get anywhere, far from it. No, it was because it handled so well and I was enjoying myself so much that it just happened that way. On a longer run with a bit more self restraint the appetite for unleaded diminished noticeably.

I appreciate that I'm sounding like a bit of a fanboy here, and that's not the intention. But I do have to admit that I came into this review really unsure what so many people saw in the GS or how it managed to command such an incredible loyalty. And while I may not be a convert - I still don't think it's really my thing - I do get it. It's an extraordinarily good motorbike.

SB

Thanks as always to g Vines of Guildford in general and Simon in particular for their demonstrator. Nice people to deal with, and they know a thing or two about motorbikes as well... Give them a shout if you're in the market for something and see what they have to offer.