2WD system is said to not only offer better traction during
acceleration, but also improved straight-line stability and a higher top
speed in slippery conditions. Yamaha says the WR450F 2-Trac can attain
a maximum speed about 10% higher than its conventional counterpart due
to the extra traction provided by the extra driven wheel.
"You also will realize quickly that the 2-Trac motorcycle has
a much higher steering stability both in a straight line as well as in
corners," adds Olivier. "It feels a bit like carved skis - you can lean
into corners and the rear part of the bike takes up the same track
easily without sliding. It makes riding much more relaxed when you don't
need to counter-steer."
Olivier says that two-wheel-drive, in addition to gaining a
traction advantage, can be a bigger benefit for beginners than experts.
"Just lean into the curve and the rear part of the bike automatically
takes up the same track. You quickly get used to it and riding becomes
quite natural. Since the rider does not need to counter-steer and can
avoid rear wheel slides, control of power becomes much easier. Unlike a
conventional motorcycle where even an experienced rider will fight with
a sliding tail end, the 2-Trac is much more controllable."
Yamaha's experience in the rally has also proved the
durability of the new system under harsh conditions. Both bikes entered
suffered no mechanical woes over the course of the event. And with the
system being much lighter and better integrated than past designs, it
would seem to be a natural to soon crank them out on the assembly lines.
While Yamaha remains tight-lipped about those plans, Olivier has high
hopes for an all-wheel-drive production motorcycle.
"I can imagine such a system fitted on any kind of off-road
motorbike, or even scooter or road bike. Two-wheel drive would be
beneficial on a large Grand Tourer or scooter for example, since you
could combine high power in an integral transmission with coupled
braking, to offer the ultimate safety both for experts and in particular
for novice riders."
To further elaborate about the benefits of the 2-Trac system,
we bring you this interview with Lars Janson, R&D manager for future
projects at Ohlins AB in Sweden, that was featured in the Yamaha Design
did you choose a hydraulic drive system instead of a mechanical one
like a chain or shaft?
Lars Janson: If you have a three-dimensional vehicle like
a car, where you can reach the wheel hub from the side, it is very easy
and efficient to fit a mechanical drive. But a motorcycle is
two-dimensional. You must have a very complicated mechanical
transmission to reach the front wheel. The components in the
transmission are not so easy to conceal either. With our hydraulic
transmission you can keep the standard layout, with the well-proven
Q:It is known that the efficiency of a hydraulic
transmission is lower than of a mechanical one. How can you justify
wasting all that power?
LJ: Yes, that is true. But in a motorcycle application
the front wheel can just transmit very little power. Normally 5 % and
less. But what is important is, if your rear wheel starts to spin, then
you lose lots of power. What we are doing is to take some of that wasted
rear-wheel spin and instead transmit it to the front wheel. So even if
we lose some efficiency in the hydraulic transmission, we are gaining
lots more by reducing rear-wheel spin.
Q: The drive is "smart" and gives only a certain
percentage of power to the front wheel, depending on the present
condition. What is the benefit of this solution?
LJ: The most important function on a vehicle is
steering. Regardless of other qualities, if you can not steer your
vehicle in the direction you want you can just as well walk. A
motorcycle is high and short and very powerful, so if you can't limit
the power supply to the front wheel you will get excessive front-wheel
spin and no steering capability. On a motorcycle you definitely need
some rather sophisticated governing of the power that reaches the front
wheel. With our hydrostatic transmission you have inherent the smooth
application of front wheel drive - important in corners - and spin
limiting capability so you never lose your steering.
Q: How does the system influence the riding
character of the machine?
LJ: When an experienced rider tries it for the first
time, and especially if the application is made on a model he has great
rear-wheel drive experience on, he thinks that the bike is down on power
- he can't spin the rear wheel as he normally does and he can't do power
slides like before. But if he is timed on a racecourse, he realizes
that he is much faster than before. From above we know why. We have
reduced the excessive wheel-spin and instead made effective front wheel
pulling force of it. Apart from the obvious advantage of the improved
traction, especially in sand and snow, we have noted improvements in
following riding situations: Better high-speed stability; better
possibility to change direction in corners; better stability and
earlier throttle application possible during corner exits; better
stability going up hill. The experienced rider can also benefit from
the spinning front wheel (providing gyroscopic force - Ed) during
wheelies and while airborne in a jump.
you see benefits of the 2WD system for other uses like streetbikes or
LJ: Yes, definitely. We have done 2WD applications on
a big variation of motorcycles. You can say that the bigger and heavier
the bike is and the more inexperienced you are as a rider, the more you
can benefit from 2WD, especially off-road and on gravel.
Yamaha has a history of being at the forefront on new
motorcycle technology, for better (4-stroke dirtbikes, 5-valve cylinder
heads) and for worse (the GTS1000 with a single-sided front swingarm
instead of a conventional fork). With the recent success of the 2-Trac
system, we might expect to see something in the showrooms by the
And it makes you wonder how Carlos Checa might go on a 2WD
Yamaha YZF-M1 on a wet Grand Prix track...