one of the most significant moves in motorcycle history, Yamaha
has announced that it will release a two-wheel drive motorcycle
early in 2004.
Though it is not the first two-wheel drive motorcycle
in history, the new machine will be a landmark model as it seems
certain to be the first of many - testing over the last five years
has indicated enormous benefits in terms of safety, traction and
(probably the one that counts most) outright cornering speed in
slippery, sandy or muddy conditions.
Though the first motorcycle to be offered with
Yamaha's 2-Trac system will be an off-road competition machine based
on the WR450F enduro machine, tests on an R1 1000cc supersport road
bike have shown an incredible speed differential on wet tarmac -
tests at the tight Swedish Karlskoga roadracing circuit showed the
2-trac-fitted R1 to offer a whopping five second per lap advantage
over a standard machine when the circuit was wet.
Developed by Yamaha in conjunction with the race
department of Öhlins (best known for its competition shock
absorbers), the release of the new machine is the culmination of
nearly twenty years of testing of both mechanical and hydraulic
Research initially began in secret in 1985 but then
in 1998, a prototype 2-trac-equipped YZ250 motocross bike was revealed
to the press, and the following year, Yamaha-raced a 2-trac-equipped
TT600R in the UAE Desert Challenge. In 2001, Jean-Claude Olivier,
President of Yamaha France, raced a 2-trac-equipped WR426F into
fifth place in the rally of Shamrock. Then, in 2002, David Frétigné
and Olivier scored a 1-2 finish for the French TEAM at the shamrock
rally aboard 2-trac-equipped WR426Fs.
it works - The patented 2-Trac system uses a hydraulic
pump located above the gear box, and driven by a chain (in an oil
bath) driven from the gear box. The system comprises a pump connected
by flexible hoses to a hydraulic engine located in the hub of the
front wheel. The 2-trac is a closed loop system equipped with filtration
system and is a self-regulated compact unit. The hydraulic pressure
transmitted to the front wheel is proportional to the speed of the
rear wheel: the more the rear wheel loses traction, the more the
hydraulic system compensates by increasing the traction power to
the front wheel. The distribution of the power between the front
and rear wheels is variable in order to optimize traction. The front
wheel can never turn quicker than the rear wheel, and the power
transmitted to the front wheel is never higher than that used for
the rear. This self-regulated system also allows for the conditions,
so that the power to the front wheel is slowly reduced so that the
rear wheel "recovers" traction.
When the throttle is closed, no power is transmitted
to the front wheel, but if the throttle is opened abruptly and that
the rear wheel starts to lose grip, the sudden increase in pump
revs increases the hydraulic pressure of the system and a higher
proportion of engine power is transmitted to the front wheel. If
the rear wheel continues to spin, more power is sent to the front
wheel. The proportion of the engine power provided to the front
wheel is hence controlled by both the throttle and the traction
of the rear wheel.
Mechanical or Hydraulic - Two
technologies can be used to transmit power to the front wheel of
a motor cycle: mechanical or hydraulic. On a car, the power is transmitted
mechanically to the wheels by driveshafts but from an engineering
viewpoint, a motorcycle is essentially a "two-dimensional"
vehicle, and to transmit power to the front wheel isn't easy. The
situation is complicated by the fact that a hub of front wheel on
a bike is surrounded by the forklegs, and in certain cases by double
discs, making the hub even more difficult to reach.
majority of the prototypes constructed by Front wheeland Yamaha
used a mechanical drive by chain or gears connected to the front
wheel. These systems were found to have many disadvantages: they
were heavy and complex and required high maintenance. Another problem
associated with mechanical systems is that fitting them required
complex modifications to the frame and suspension.
Simple,light and effective hydraulic system
- By comparison, an hydraulic system is relatively simple, light,
compact and discrete: it is for all these reasons that Yamaha and
Öhlins chose the hydraulic system. On a conventional rear-wheel-drive
bike, the rear wheel patters on loose surfaces and the engine power
is not completely transmitted to the ground through the rear wheel.
By diverting 15% of the power to the front wheel, the 2-Trac system
decreases the power loss from lack of rear-wheel traction and offers
better overall traction. Another advantage of the 2-Trac system
is that it easily adapts to any machine without requiring large
changes to the engine or frame. For these reasons, Yamaha is convinced
that a hydraulic system is the best for motorcycles.
What does it feel like to use?
- The 2-Trac represents one of the most significant developments
on the off-road scene for many years, and its potential impact can
be compared with that of the first 4x4 off-road cars. "While
riding with the WR450F 2-Trac, you will be surprised by its capacities
and its performance in the most difficult situations as sand or
mud," according to Jean-Claude Olivier, President of Yamaha
Motor France and one of the main test pilots in the development
program. " The WR450F 2-Trac motor bike passes where the a
standard WR450F digs in," he said.
addition to excellent traction on wet or poor surfaces, the 2-Trac
system also offers improved straight-line stability as well as in
corners. You turn into the corner and the rear end of the bike follows
the same trajectory as the front wheel. This is quite different
conventional enduro bikes where you must battle with the rear end.
In the turns, the WR450F 2-Trac is easier to control, and that represents
an unquestionable advantage for both beginners expert riders "
The tests also revealed that the corner speed of the WR450F 2-Trac
is 10% higher on the sandy tracks thanks to its increased traction.
The 2-Trac will be produced for competition motorcycles
only at this point, but Yamaha has been very keen to point out that
the current 2-Trac system has enormous potential to be used on motor
bikes or scooters in the future. Yamaha has already noted in its
pres release that the system is easily adapted to existed machines,
and the press release specifically mentioned the possibility of
the system being fitted to the Yamaha R1 road bike and the T-Max
One wonders how long it will be before we see the
2-Trac system employed on roadrace machinery which also suffers
from rear wheel traction problems - could this be the killer-app
which enables a 250 horsepower MotoGP bike to feed a bit of that
tyre-shredding rear-wheel spin into additional front-wheel traction.