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Brave New World
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Bimota Tesi 2D & Vyrus 985 C3 4V
Jeff Buchanan
11/01/2006
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Photography by Cordero Studios/corderostudios.com
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Once up to speed the most noticeable and welcome trait of the
hub-steer/front oscillating swingarm design is that it is almost completely
devoid of front-end dive under braking. The sensation, especially at racetrack
speeds, takes a little getting used to. Sitting up at the end of the
straightaway at 120 mph and aggressively getting on the brakes results in the
bike merely decelerating rapidly.
Yamaha’s GTS put hub-steering to work on a sport/touring bike in the 1990s. Photograph by Yamaha photography.
Entering corners, the hub-steer motorcycle
is extremely stable due to the fact that the front suspension retains its full
range of movement. Whereas a telescopic fork collapses under the weight shift
forward during braking and uses up the damping effect of the front suspension,
the hub-steer/oscillating swingarm continues to absorb the forces being
collected by the front wheel. The resulting stability is the machine’s magic,
giving a rider a new awareness of how much speed can be carried on corner
entry.
Because there is no compression of the suspension under braking,
initiating turn-in has a deceptive ease to it. By design, the bike does not
succumb to the changing rake encountered with compression of a traditional fork.
This translates into highly desireable consistent handling characteristics. With
the absence of dramatic attitude changes due to the unavoidable weight shifts
incurred during braking and accelerating, the transitions are is smooth and
controlled.
 Photograph by Jeremy Henrie. (Click image to enlarge)
The advantages of the oscillating swingarm become apparent in
the bike’s confident display of mid-corner stability. Once the motorcycle has
been put onto its line it feels as though it is on rails. We have all read this
interpretation before, but, for the first time, the description truly has merit.
Another attribute of the Tesi 2D is the consistent, light feel of the front end.
This is due to the forces of inertia on the steering mechanism being greatly
reduced through the “indirect” design.
But, even with all these positives,
the hub-steer/oscillating swingarm design has fought an uphill battle for
acceptance. In the public’s eyes, it remains an unorthodox approach with odd
looks. However, consider where the concept may have progressed to if the
industry had placed the same level of focus and development that has been spent
on the telescopic fork.
Problems for a racing application stem from the
compli-cated design that inhibits fast wheel changes, a serious deficit given
the frequency of tire changes required in competition. Another troublesome
glitch is the danger of having the steering linkage exposed to crash damage.
Continued development will be necessary to eliminate these design
aspects.
Hub-steer motorcycles look odd because they
defy our accepted perceptions of what is normal. But, remember, there was a time
in the mid-to-late-1800s when all bicycles were built around the Penny Farthing
design; the extremely large front wheel with a tiny trailing wheel. It is easy
to look back now and think how odd the design platform was. By the same token,
in 100 years, people may look back at our beloved motorcycles with telescopic
front forks and ask, “Did they really ride those things?”
www.bimotausa.com
www.vyrus.it
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