win the 1983 500cc World Championship,
Honda’s first in the premier class.Kalex: “They’ve got the swingarm
pivot in a better place now. And the rear
engine mounting points are closer to the
pivot, so you don’t get a long lever effect,
which can overrule the swingarm. Also,
the swingarm pivot area is strong and
you can let other parts of the frame flex;
if they were already thinking about that
kind of thing.”Öhlins: “This chassis was quite con-
ventional but it worked well. They’ve used
an upside-down Pro-Link rear suspen-
sion to make more space for the bottom
expansion chamber and the shock is gas-
charged. The frame designers have done a
good job around the headstock: it’s a lot
stiffer compared to earlier designs.”` 1984 Honda NSR500
HRC changed its engineering group
every few years, to introduce new ideas
and push young designers. Back then,
engineers didn’t know that a motorcycle
needs a reasonably high center of gravity
to help it turn and pitch back and forth to
load the tires. This bike taught them the
truth! The 1984 NSR won six races but
lost the title to Yamaha.Kalex: “Lowering the center of grav-
ity in a car works very well, but it doesn’t
make a bike faster! Like the 0W61, it looks
like they built the engine and then won-
dered where and how to mount it. They
found a solid part of the engine for the top
mount but it’s a long way from the head-
stock, so they’ve made big profiles around
the steering head and pressed recesses to
make it stiffer. You can see the castor an-
gle is getting steeper and there is a higher
swingarm pivot for more anti-squat, so
the more engine power you apply, the less
the rear suspension extends. The low gas
tank isn’t good, because when the fuel
load is low the rider will lose the front by
the inertia of the fluid moving around.Öhlins: “This looks like a spinoff
from Andre de Cortanze’s Elf endurance
bikes, which carried the fuel under the
engine. De Cortanze was a car engineer
who thought a low center of gravity would
be great on a bike. It’s crazy French en-
gineering, but in some ways I love it!
The forks have Honda’s TRAC anti-dive
system, which closed off damping valves
during braking—but didn’t really work!”` 1984 Yamaha 0W76
You could argue that this was the
start of the modern era. This was the
first aluminum spar-framed 500, Yama-ha’s Deltabox. It wasn’t Yamaha’s original
idea, but was inspired by a 1982 250,
built by Spanish genius Antonio Cobas.Kalex: “The thinking in this bike
is more modern and mostly follows im-
proved tire grip, so they had to separate
edge grip and drive grip, so they had to
make a chassis that separates lateral and
torsional stiffness. Then there’s the tran-
sition area when you’re accelerating and
loading the rear tire, so you have torsion-
al and lateral bending. The more drive,
the more torsional bending you have. It’s
always a compromise in motorcycle rac-
ing—you never find the perfect balance!”Öhlins: “Now they have one beam
section, one line connecting the swing-
arm pivot to the headstock. And the forks
are wider, up from 41mm to 43mm. From
this point they started making everything
stiffer and stiffer—which kept on going
until it peaked in 1993.”` 1989 Honda NSR500
Honda engineers struggled to build a
chassis that could cope with the 170-bhp
NSR engine. In 1988 they went too soft,
so in 1989 the frame was repeatedly stiff-
ened. Eddie Lawson used at least seven
different frames during the season to win
the title at the final race.(Above, Left) The 1989 Honda NSR500 saw engineers repeatedly stiffen the frame to handle the 170-horsepower V4. (Above, Right) The 1984 Yamaha
0W76 had the first 500cc GP aluminum twin-spar frame, the Yamaha Deltabox. (Below, Left) The 1984 Honda NSR500 fuel tank was under the engine,
reducing the bike’s ability to pitch back and forth, load the tires, and turn. (Below, Right) The 1996 Honda NSR500 was the ultimate result of Eddie
Lawson and Erv Kanemoto putting the NSR on the right development path in 1989; the NSR500 is the most successful premier-class racebike ever.
Roadracing World, August 2019—23