Monday, October 19, 2009

Other Desirable Bikes (part 2)

Continuing on the theme of other superlight, exotic sportsbikes.


Have you ever seen one of these?...

If you think it is a Bimota Tesi 3D then you'd be wrong. The Bimota is exotic enough but, at 168kg dry, it doesn't make it in terms of being light weight in my opinion. No, if you want a really exotic alternative front-end motorcycle then check out the VΨRUS 984 2V.

The VΨRUS shares more than just a passing resemblance to the Bimota Tesi. The small company that builds the VΨRUS is based in Rimini, Italy, just down the road from Bimota. Ascanio Rodorigo heads the company and cut his teeth working for Bimota in the 1980's. At some time, during the many boom & bust cycles of Bimota, Ascanio gained the rights to build bikes based on the Tesi's hub-center steering design.

Hub-center steering does away with conventional telescopic forks. Instead there is a pivoting arm at the front (much like a single-sided rear swingarm) which is supported by a conventional shock-absorber. The wheel steers left and right via a steering pin located inside the hub of the front wheel. This is much like the way a car front wheel is steered. A series of levers connects the handlebars to the steering on the front wheel.

Hub-center steering offers many advantages over telescopic forks. Here are just a few:
  • Telescopic forks connect the front and rear wheels via a triangle with one side removed. This is a poor engineering choice. To compensate, sportsbikes use massively stiff front forks mounted to a strong and complex frame. The hub-center design connects front and back in a direct line, the optimal solution.

  • Telescopic forks suffer from 'stiction' as the forks slide against each other. To compensate, sportsbikes use exotic materials and fork-tube diameters are increased. The hub-center design simply pivots up and down on a bearing surface.

  • As telescopic forks move up and down they carry the extra weight of their internal shock absorbers. This compromises the suspension. 'Upside down' forks compensate for this somewhat. The only other solution is to use exotic, lightweight materials to try to reduce the unsuspended mass. In hub-center designs, the shock absorber is fully suspended weight.
All steering, braking and front suspension parameters can be tuned, separately from each other, since this system separates the steering, braking and front suspension functions from each other (think tunable anti-dive braking).

Over the years telescopic fork suspension has evolved to the point where a bad design actually works remarkably well. It was not always the case. Telescopic forks have one other advantage, because they are tilted back (raked) they can absorb the 'rearward' component of the force due to bums in the road.

Ascanio and his team perfected the Tesi design and the super-refined result is the VΨRUS.

Currently there are two models available. The 984 2D and the 985 4D. The main difference is that the 2D uses Ducati's 2-valve, air-cooled, 1000cc V-Twin; the 4D model uses Ducati's 4-valve, water-cooled superbike engine.

I chose the 2D for this article because it is the lightest and simplest of the two. At 150kg it is very light for a 1000cc twin, but just makes the grade overall for the superlight category... well 150kg is a bit outside the range really, but this bike is so exotic that I just had to include it.

Cost is a bit out of the range too. In 2006 the price of a 2D was around $40,000 so expect to pay that and a bit more today (sorry I don't have any recent figures).

I have a lot of respect for Ascanio Rodorigo and the VΨRUS team. Like CR&S, they are a small company with limited resources that have produced an exotic masterpiece using great skill, passion and the drive for perfection above compromise.

By the way, Vyrus will be unveiling some new, even more exotic, models at this year's Milan International Motorcycle show (EICMA). Just one more reason to be there.

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