As anyone lucky enough to stand, slack-jawed, in the MotoGP pits will tell you, prototype racing ist the ultimate. Being close to a completely hand-built motorcycle, designed by the world's cleverest engineers, dripping with secrets, you suddenly realise there is nothing beyond this. What your're seeing is the best they can do - the cutting edge.

There's a catch, of course: a MotoGP pit lane is normally forbidden territory to grockles like you and me. Virtually all the racing machines we actually smell and touch are glorified production bikes. From a ratty 600 Hornet club racer to a Yamaha YZR250 to Toseland's Ten Kate Honda: they all started life in a crate.

Only two small (but international) championships buck the trend, by encouraging teams to make entirely new motorcycles. The first is Supermono (see October's Obsession), where anything goes as long as it's a four-stroke single. The other is the same thing for twins and triples: Sound of Thunder. Free of the need to act as subliminal marketing for the factories, SoT is all about charisma and noise. It pitches 180bhp ex-Hodgson Ducatis against super-light 11OOcc NCRs and grunting 1350cc Buells. Plus, of course, anything else competitors build.
Such as this jewel, crafted in Germany by Alex Baumgärtel and Klaus Hirsekorn, to compete in the 2008 European series. This is the AV1 - one of the most brilliantly designed and constructed motorcycles we have seen. If the late, great John Britten were still with us, and happened across Klaus and Alex's bike in pit lane, he would stop, stare, walk round it a few times -and break into a grin of pure joy. It's nowhere near as radical as Britten's frameless New Zealand racer, but in terms of thought, layout and pursuit of perfection it's solid gold. Ignore the Aprilia RSV-R road bike motor and this thing could be on a MotoGP grid.

THE BASICS
'I was going to buy a house,' mutters Alex when asked how he and Klaus managed to spend two-and-a-halfyears and €80,000 creating the lightest possible race bike around the lOOOcc V-twin. 'We did this instead.' They both work for Holzer, a German racecar tuning consultancy - Klaus on fabrication, Alex on computer assisted design (CAD). This mix of skills (and a very understanding boss) meant almost the entire bike was planned and mapped out inside a computer. Only when each component was finalised did Klaus make it. As far as we know, it's the first bike outside amajor factory to be built in this way*.

Using such a powerful design tool leads to some pretty fundamental questions - the kind normally answered only inside factory R&D departments. How long? How wide? How stiff?And before all that, what engine? 'We considered the KTM twin, but at that stage it was just an enduro engine and still quite new,' remembers Alex. 'It could have been shit. Ducatis are very hard to make compact, while the Honda and Suzuki are old. So that led us to Aprilia- and the RSV's a dry sump engine, which is good for packaging.'

'It's bloody heavy though,' chips in Klaus. Alex dreams of a V3 engine, like an old Honda NS. It's so logical. But he needs a few million for that.' The big problem with a V-twin is getting it far enough forward without the tyre taking out the front cylinder on the brakes. So Klaus measured a set of datum points on the motor, which Alex imported into the computer. 'We looked at the standard Mille's relative position to the front wheel and tried to get it as far forward as possible, while keeping an acceptable bend on the header pipe. We found it could be 15mm further forward, so we lengthened the swingarm.'

That gave the wheelbase and engine position, but still left a fair margin for refining weight distribution and centre of gravity. 'For front/rear balance we looked at many bikes before deciding on 52.5 front/47.5 rear. When we measured the finished bike it was 52/48,' confirms Alex. Centre of gravity height was equally important for optimal braking and for traction under acceleration. The computer could take the weight and position of major components into account, so Alex tried different options on screen. He settled on 630mm above ground without a rider- and two years later measured it. 'It was within 8mm of target,' he reveals. i 'I think with the right set-up we should be able to pull 1G on the brakes,' Alex adds. 'If not, ~^we have the option to add ballast. Ready to race it's 164kg, on our scales or 155kg with no fluids at all. The weight limit is 165kg anyway.'

CHASSIS
If you're used to bulky aluminium beam frames, this tubular lattice looks inadequate. But steel is stiffer than aluminium for a given volume and the KAlex is all about being slimmer, smaller, lighter. One payoff is the way the coolant pipes, harness and frame tubes take up the bare minimum of space. Another is the world's most accessible rear shock. 'The frame is 15CDV6 aerospace-spec steel,' Alex says. 'It doesn't need heat treating after' Okay, Team Roberts do it too - but in this context they're a major factory welding, so it can go straight to machining. The Aprilia Mille frame was 10.5kg; this is 9kg.' It's also 50mm narrower than a Ducati frame, so it's not exactly bulky.
The only trouble is the clutch cover now sticks out a mile. Klaus reckons a clutch and cover rework could narrow it by 27mm. If that sounds too precise to be believable, consider how Alex fixed the swingarm pivot point. 'I had to do a bit of calculation involving the c of g, estimated engine torque and front sprocket position. I wasn't sure, so I made it adjustable, but it works superbly well.' These guys are seriously good at maths. Not to mention improvisation: the swingarm pivot support section doubles up as an engine breather tank.

ENGINE
The motor only makes 127bhp at the moment, but with good reason: it's totally standard apart from a Motec fuel injection set-up. Even the starter motor is still there. SoT rules allow an l1OOcc overbore and lots of tuning, which Alex expects to give a reliable 160bhp. For now, the forward-facing intake sits at the point of highest pressure and flows cool air around a streamlined headstock, through a mesh filter and straight into the airbox. The MotoGP-style exhaust was unbelievably difficult to make: Alex's front downpipe design, which goes from oval port to round tube in 60mm, had to be constructed from sheet metal. It took 39 attempts to get right - on a tiny piece nobody sees and will probably have to change again anyway once the motor is tuned. It makes you wonder how many hours they put into building the bike. 'I stopped counting after a while,' sighs Alex wearily. 'But thousands of hours. Thousands.'

SHAKEDOWN
'The first time I took it on track I was nervous as hell,' says Alex. 'More than getting married or having a child, although my wife was angry when I said that.' When the first outings went well, they looked for some serious talent to start developing the bike. An early fan was former World Supersport and German Superbike rider Christian Kellner. 'He understood what we were trying to do and is helping with rider feedback. But his level is still above the Sound of Thunder series.' In other words, the guys are looking for a rider. Ideally, one who loves the idea of the bike as much as he appreciates the countless hours of toil that have produced it. 'Our dream would be a gentleman's racing league,' muses Klaus. 'If a rider came and said, "I'd like to ride it. It's interesting," that would be best.'
Meanwhile, they're enjoying the bike themselves. Which is how Klaus, with eerie foresight, came to discuss the inevitable over a beer in a Hockenheim pit garage. 'I fear for the moment it crashes, but it's a racing bike. Ideally we would have one each.' The next day, warming the bike up for Christian Kellner, he highsided on cold tyres at the entrance to the Parabolica. It was a disaster: what the crash didn't rip and break, the ensuing fire destroyed.
Fortunately, the CAD design meant all the patterns still existed, so the bike was rebuilt in
six weeks for its first race at Oschersleben in September. With Alex riding, it came 18th out
of 26. 'It felt good,' he explained over the phone. 'Nothing nasty. Okay, I'm not the fastest but
I improved my laptimes. Now we just need a professional rider.'

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