MotoGP chassis design has had a huge effect
on road-bike chassis design, so what have
been the biggest steps forward (or backward)
for race- winning machines since the 1980s?By Mat OxleyPhotos by Riders Club,
Takanao Tsubouchi, Koichi OhtaniF
our decades ago, 500cc Grand Prix race-
bikes started making a lot of power, so
tires got bigger and frames got stiffer.
Chasing more horsepower was no longer the
biggest deal in motorcycle racing.
That’s why the 500cc GP chassis of the
early 1980s are a million miles away from to-
day’s ultra-high-tech MotoGP creations, most
especially Suzuki’s GSX-RR, the best-handling
racebike on the MotoGP grid.
Chassis geometry has been refined,
mass-centralization has been improved, ma-
chine balance has been perfected, and chas-
sis flex has become a whole new area of racing
science to help bikes corner faster. All these
improvements have been demanded by more
horsepower, grippier tires, fiercer brakes, and
so on.
Chassis flex is arguably the most import-
ant area of cornering technology, because en-
gineers have to design frame, swingarm, forks,
triple clamps and ancillaries that provide lots
of longitudinal stiffness for braking stability,
much less lateral stiffness to help the bike track
the road surface at high lean angles (when the
suspension doesn’t really work), and the right
amount of torsional rigidity (twist stiffness) to
provide both stability and feel when the rider
spins the rear tire out of corners. In theory,
these three facets of flex should be mutual-
ly exclusive, but the job of the engineer is to
make possible the impossible. Ultimately, they
want to make the bike bend in the corner to
create an element of self-steering. It’s a very
complex science.
To guide us through the decades we spoke
to Alex Baumgartel of Kalex, the most success-
ful chassis designer in the MotoGP paddock,
and Mats Larsson, who has worked with Öh-
lins since the early 1980s.` 1982 Yamaha 0W61
Yamaha engineers spent the early
1980s in experimental mode, switching
from an Inline Four to a Square Four to
a V4 in just three seasons, so they didn’t
have much time to worry about chas-
sis design! The 0W61 featured a trans-
verse-mounted horizontal shock and was
such a nightmare to ride that “King” Kenny
Leroy Roberts only managed one win on
the bike.Kalex: “The engine is mounted very
far back and the chassis looks very weak
and flimsy in longitudinal stiffness. The
geometry looks quite extreme, with a big
castor angle and flat swingarm with a low
anti-squat angle. But the rear end does
have a tie-rod, which will pull the rear
down when the rider uses the rear brake. It
looks like a car designer made the engine,
not worrying about the people who had to
design the chassis!”Öhlins: “They’ve located the shock
like that probably due to space restric-
tions, most likely to get the best routing for
the rear expansion chambers. I applaud
them for thinking outside the box. At that
time it was still trial and error with link
systems, lever ratios and shock absorber
technology. But now you could position the
shock like that, no problem.”` 1983 Honda NS500
HRC engineers designed the NS500
very cleverly, using a small three-cylin-
der engine wrapped in a compact chassis
to beat the bigger four-cylinder bikes and10 STEPS To The World’s Best MotoGP Chassis
(Above) Start of a 2019 MotoGP race, led by a Ducati, a Honda, and a pair of Yamahas. Photo
courtesy DORNA. (Below, Right) The 1982 Yamaha 0W61 V4 featured a transverse horizontal shock
in a spindly frame. (Bottom, Right) The 1983 V3 Honda NS500 won Honda’s first 500cc GP title.Kalex chassis designer Alex Baumgartel (left)
and Öhlins suspension engineer Mats Larsson
(right) helped us analyze landmark chassis
designs in 500cc Grand Prix and MotoGP.22—Roadracing World, August 2019