Performance Bikes — March 2018

42 PERFORMANCEBIKES.CO.UK|MARCH 2018

thetyreshavealowerspringratethantheframeand
swingarm. Under full cornering load, Michelin’s MotoGP
tyres deflect (squash) by about10mm.
WhiletyresarepartofaGPbike’ssuspension,its
actualsuspensioncanbepartoftheflexequation.
Öhlins’ latest carbon-fibre forks provide immense
longitudinal stiffness, for braking stability, and lateral
flexformoregripandlesschatter.Wheelscanalso
causeorcurechatter,becausedifferentspokedesigns
spreadloadsdifferentlyandflexdifferently.

Chassis geometry
Themainelementsofaracebike’sgeometryaretrail
andwheelbase.“Youhaveanideaofwhatwindowyou
wanttoworkinandthenyoudevelopasmaller
window out of that,” explains Baumgaertel. “For
example,ridersadjusttrailquiteabitatthestartof
eachyear,whiletheyadaptset-uptosuitnewtyres.
“You adjust offset to change the trail, perhaps opening
theangletomakethebikelesssensitivewhenthefront
end dives on the brakes. Or you might go shorter, which
makes the bike flick into corners more easily, but
compromises corner-entry performance, because you
don’t feel the tyre so well when it’s losing grip.”
AllMoto2bikes–Kalex,KTM,Suter,SpeedUpand
Tech 3 – have very similar geometry because they use
thesametyres,thesameengineandsoon.AKalex
Moto2bikehastrailofjustover100mm,varying2mm
to 3mm, according to rider preference, and a wheelbase
of around 1300mm, varying up to 10mm between
riders. MotoGP bikes have slightly longer trail and
wheelbase. Road bikes aren’t dissimilar: Yamaha’s R6 is
97mm and 1370mm.
“MotoGP bikes need more trail and wheelbase due to
their higher speeds and their braking performance,”
says Baumgaertel. “When you’re leaning into corner
withninebarofbrakepressureandtherearwheelin

Triple clamps

Kalexcanofferasmall

numberof variations in triple

clamp type, which differ in

the amount of lateral stiffness

offered. Which version a rider

ends up running with is down

to the amount of force the

front tyre can take at lean.

Franco Morbidelli won the 2017
Moto2championshiponaKalex

GP TECH/CHASSIS DESIGN

‘IMAGINETHEFRAMEANDSWINGARM

CURVINGLIKEABANANA.WITHTHE

CENTREOFGRAVITYMOREORLESSIN

THECENTRE,THECHASSISMAKESA

CURVINGLINETHROUGHTHECORNER’

When a chassis

bends like a banana

through a corner the

amount of flex is just

a few millimetres

Kalex Moto2 bike’s

trailvaries2mmto

3mm, according

to the rider

BUENOS DIAS

MARC VDS