I have a theory.
More of a conviction, really. In scientific terms, I'll defend it as halfway between a hypothesis and a theory.
My theory is this: Sports tourers are the most useful, versatile and worthwhile species of motorbike, and more rides should be buying them.
It's not that we're talking about a particularly narrow definition, here, though. I'll get to categories in a moment.
But it does seem to me that sports tourers sit at a crossroads where they are jack of all trades, master of none but capable of performing just about any task so well that the average, need-one-bike-to-do-anything motorcyclist can't find their limits without either getting seriously arrested, or seriously dead.
If you want to race - get a race bike. Enduro, track, motard, whatever. Go for your life. Have fun.
If you can only afford one bike, or one bike is all you care to look after and use, get a sports tourer.
Commuting? Check. Thirstier than lighter, smaller, more focused bikes, but also, I suspect, needing less maintenance. Not actually that much larger, either - the widest point on most bikes in the mirrors and/or bars, not the fairing, and unless you really have to fight gridlock the biggest difference will be parking a heavier, slightly longer bike.
Twisty roads? That's what the "sports" part is for. BMWs have a reputation for being able to seriously frighten sports bikes on mountain roads, and that's what they should all be like.
Distance? That's the whole point, of course. These bikes show that "sports" doesn't mean "uncomfortable". Sure, you can tour on an MV Agust F4 - people have - but why do that to yourself unless you really, really can't go past an MV without masturbating uncontrollably?
Carrying pillions? With rare exceptions or strange oversights, most of them are designed for it.
Maintenance? Bikes designed for long distance are generally tougher than bikes designed to shave grams with more delicate tolerances, or to excel at very narrow requirements only. Particularly if you get a shaft drive.
Off the beaten track? We'll get to that.
So what are the categories?
I claim there are three, two with blurred distinctions and one which has been absorbed into the family as time has passed.
First up, there are the wanna-be racers. Bikes like the Triumph Sprint ST, current king of the category, and the Honda VFR750/800. The VFR750 was, in its earlier incarnations, winner of the inaugural World Superbike Championship. Then it got overtaken by the sharper, more focused CBR series and it became, instead, one of the most popular bikes-to-have-if-you-can-only-have-one-bike. The 800 alienated an awful lot of people by introducing VTEC, which was a complicated answer to a problem with a more obvious solution - a bigger engine - and linked brakes, which insulted the very people most likely to buy a pensioned-off superbike like the VFR.
These bikes are generally equipped with a crouched riding position, seats leaning more towards racer-firm than long-distance plush, and aggressively styled full fairings. They have chain final drives and frequently have sexy sports-style single-sided swingarms as well. At the upper end, this category goes to bikes like Honda's CBR1100XX Super Blackbird and Suzuki's GSX-R1300 Hayabusa, bikes which existed for the sole purpose of being The Fastest but, particularly in the case of the Blackbird, grew luggage because there really wasn't much point in having one, otherwise.
Most of them have four-cylinder engines unless the company, e.g. Triumph or Ducati, don't make them.
The second category is the one championed, and more or less invented, by BMW - bigger, heavier bikes that don't look sporty until you ride them, with shaft drives and generally larger fairings but still huge amounts of power and hugely capable handling. My K100RS is pretty much the archetypal example of the breed, complete with what BMW described as a "three-quarter cafe crouch". The Kawasaki GTR1000 which followed the first K bikes has a cult following who believe it's better, and a string of hugely fast GTRs and Yamaha FJRs have bolstered a category which just keeps growing. This group is more likely to have a variety of engines, with various forms of twin joining the more common fours.
The third category is of course the interloper - the Adventure Tourers, Dual-Sports, Road-Trails. The category commonly understood to have begun with BMW's R80G/S of 1980 and lead by various G/S and GS models until the new R1200GS with four-valve cylinder heads, a bike with such a solid sales performance that the R1200ST, the more traditional sports-tourer, is no more.
Adventure Tourers have been absorbed into the ST pantheon recently, helped by the fact that more and more companies are building bikes with a more and more token nod towards the dirt. On the one hand, the KTM 990 Adventure is a bigger, more powerful, faster, road-legal Dakar racer. On the other end, the Ducati Multistrada has been the epitome of the dirt-styled road-bike that combines comfort (for a Ducati), touring range and more fun than should be possible while fully dressed. These bikes come with chain or shaft final drives, all sizes, all degrees of seriousness, and all of them hugely practical and with vast potential for fun. All of them are twins save the triples from Triumph and Benelli.
If you're in the market for a bike that does everything, get a Triumph Sprint ST or a BMW K1300S, depending on budget and whether you want to waste time oiling a chain or not. If you are really in the market for a bike that does everything, get a BMW R1200GS. If you plan on trying to cross the Nullabor any time soon, get an R1200GS Adventure.
I'll see you on the road.