MotoGP set-up report - Le Mans, France

Le Mans, France
9/5/2005

Round 4: Le Mans, France
Track length: 4180 m
Opened: 1965
Fastest Lap Ever: 1' 34.088 (Max Biaggi, 2004)
MotoGP lap record: 1' 34.088 (Max Biaggi, 2004)
Last year MotoGP winner: Sete Gibernau
Circuit web site: http://www.lemans.org

2004 MotoGP race summary

Carlos Checa took a well-earned second in the 2004 French Grand Prix after a
close-fought race with Sete Gibernau (Honda) in Le Mans, France. Although his
Yamaha team-mate Valentino Rossi was unable to overcome the set-up problems
which had plagued his YZR-M1 all weekend, the young Italian still finished a
strong fourth after a hard fought battle with Max Biaggi (Honda).

Checa managed a strong start from second place on the grid to immediately take
the lead, with Rossi in third. Pole-sitter Gibernau gradually closed the gap
from behind before overtaking Checa on lap 11 and then continuing on to take his
second successive Grand Prix win of the year.

Meanwhile Biaggi made his move on Rossi and before making up the lost ground on
Checa. The Spaniard rode a hard race to fend off the Roman Emperor, eventually
crossing the line just three tenths of a second ahead of Biaggi. In the midst of
all this Rossi closed the gap between himself and Biaggi, considerably, in the
closing stages - passing him momentarily on lap 25, but was unable to stay ahead
at the line.

2005 Set-up report YZR-M1

Le Mans is a circuit made up of a number of second gear hairpins linked together
by a series of long straights, with only the occasional chicane breaking up the
run to the next hairpin. A design of the past, the French circuit causes little
concern for engineers regarding set-up. Turns three and five are the most likely
passing points and all efforts will be focused towards finding stability under
brakes in these areas.

The YZR-M1 therefore requires a heavier spring rate on the front to deal with
the aggressive weight transfer as the rider dramatically decreases his velocity,
while still providing the ability to soak up any bumps entering each of the
slower turns. The latter will be taken care of by the Öhlins front-end
compression damping. Meanwhile the fork rebound will be dialed in to offer a
more controlled return to the fork's full length. This will be done in an effort
to offer stability as the rider makes the somewhat aggressive, almost light
switch like transition from the brakes to the throttle in the chicanes.

In addition to the heavy fork springs the bike's attitude will be set to ensure
stability with the rear. This is achieved with a slightly lower rear
ride-height, lowering the center of gravity, in turn helping to prevent the rear
tyre from rising off the track's surface. Progress made on braking stability
throughout pre-season testing and during the first two rounds of the 2005 season
will pay dividends at the stop-go styled Le Mans circuit, as will the M1's
lightweight steering character - especially through the quick chicanes.

This approach is in fact a compromise, but it's a set-up that will be the most
efficient on a circuit with this classic character. The improved stability will
affect the cornering characteristics by reducing its turn-in agility slightly,
but experience has shown the Yamaha is one of the most agile bikes in the
championship and the slight loss here is minimum compared to the gains made up
under brakes.

Meanwhile drive off the turns must not be neglected; but with the rear
ride-height reduced for stability the ability to hold the racing line, while
exiting a corner, is compromised to a certain degree. Therefore a softer rear
spring rate will feature on the M1 for good predictable feedback, but it will be
dialed in with a high degree of preload to prevent the rear-end from squatting
under power as the weight transfers to the back of the bike. As the Le Mans
corners are short and sharp the rear shock linkage ratio therefore plays an
important role at compensating for the softer spring rate by providing a
movement which is initially firmer.