Performance Bikes — March 2018

40 PERFORMANCEBIKES.CO.UK|MARCH 2018

ACING MOTORCYCLESaremuchstranger

machines than racing cars. Late, great

Suzuki, Yamaha and Team Roberts engineer

WarrenWillingusedtosaythatracebikes

have more in common with a fighter jet,

simplybecausetheyworkinsomany

different planes.

Aracebikeisalmostneverinastatic

phase: the rider constantly moves his body

around the motorcycle, loads are always

changingfromfronttobackandfromsidetoside,the

geometry changes all the way through a corner, as do

tyrecircumference,tyrecontactpatchandsoon.Itis

thechassisdesigner’sjobtocreatethebestpossible

compromise between umpteen conflicting demands.

Themostsuccessfulchassisengineercurrently

workingintheMotoGPpaddockisAlexBaumgaertel,

onehalfofthedesignteamatKalex.TheGerman

companyenteredGrandPrixracingin2010andhas

since won 85 GPs, plus nine riders and constructors

worldtitlesintheMoto2class.Kalexdon’tbuild

MotoGP chassis, but the principles in both categories

aresimilar:thebikesareofsimilarsizeandweightwith

similartyredimensions;theMotoGPbike’sgreater

horsepower is the only major difference.

Alex Marquez was fifth overall
on the Kalex-framed Moto2
machine in 2017
MARC VDS

Who are Kalex?

Kalex engineers Alex

Baumgaertel and

Klaus Hirsekorn were

car race engineers

who decided they

prefer bikes. The

German duo built

their first motorcycle

chassisin2004and

hitthebigtimein2010

when they created a

chassis for the new

Moto2 world

championship. They

won the title the

followingyearand

have dominated the

series since.

This being the 21st

century, it all starts on

a computer screen

Chassis stiffness and flex

Flex is the busiest area of MotoGP chassis R&D, partly

becauseit’ssuchahazysubject.Constructorscan

measure flex, but it’s not so easy to calculate how each

designworks,exceptbytrialanderroronthetrack.

Engineersbuildflexintochassisformanyreasons.

Mostly,wearetold,amodicumoflateralflexcushions

therideathighlean,whentheforksandrearshockare

almost completely useless, to help the tyres track the

tarmacbetterandincreasegrip.But,infact,flexhasa

Longitudinal/lateral forces

Engineering a great amount of longitudinal

stiffness into a chassis can improve rider

feeling during heavy braking and turn-in.

The challenge is in separating longitudinal

and lateral forces...