Bike India – August 2019

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Rubber

Side

Up,

LLC

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Honda

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MV

Agusta

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Arson/Roaring

Toyz

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Hesketh

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Arlen Ness

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Next World Design

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Sbarro

good side/bad side approach, although by the time brakes, forks, and other assorted
componentry was added, the difference was never as evident in reality as it sounded.
Over the years, wheel diameters have varied with understanding, fashion, technology,
and the quality of road surfaces. Larger wheels are better at traversing potholes and
rough terrain, which is why most off-road models still employ 21-inch front rims (I recall
off-road riding with my six-year-old, when my 21” Yamaha Ténéré would easily roll over
holes that his PW50, complete with 10” rims, would entirely disappear into, with
disastrous results). However, larger diameter rims are less stable torsionally, in a simple
proportion of height to width, and 17” has become standard street-bike specification
almost across the board.
Both rim size and what I will call rim density are also used as a styling ploy to adjust
the effect on the visual weight of a motorcycle. Although sport bikes mostly use 17” rims
front and back, the front wheel is packed with brakes, thick forks, and a mud-guard set
close to the tyre, all of which add plenty of visual weight to the front. This is often
combined with large scoops on naked bikes (or low-placed side-panels on faired
models) to link the front wheel to the main mass of the motorcycle. The rear wheel, by

contrast,hasplentyoflightness,thankstoa smallerbrakeandchain,anda high-placed

mud-guardthatleavesplentyofairspacearoundthetyre.Thevisualweight emphasis is

stronglyplacedtowardsthefront.

Custombikesdothingsinexactlytheoppositeway.Thefrontwheelis of large

diameter,witha thintyreandsmallbrake,givingplentyoflightnesstothe front of the

bike.Moreover,thefrontwheelis pushedawayfromthecentralmassbylong forks. The

rearwheelis smallindiameterandsometimesevensolid(H-DFXSTCSoftail

Custom),witha thicktyre,theenvelopingrearmud-guardleavingnoairspace and

fusingtherearwheelvisuallywiththecentralmass.Here,thevisualweight bias is

clearlytowardstherear.Wheelproportionsarefundamentaltomotorcycle design and to

whatfunctionorridercategoryweperceivethosedesignstoportray.

Colouringis anotheraspect.Afterdecadesof silverpaint,chromeorpolished metal,

blacknowseemsto bethemandatorychoiceonbothtwowheelsandfourto generate that

gangsterlook.However,it makesthewheelvisuallymergewiththetyre,looking heavy

andnegatingsomeof thestylingtricksI justmentioned. Colour

showsdetailandaftertwodecadesof blackwheels, surely, it’s time

fora change.Onealternativeis colouredtyres,which vied for a

comebacka fewyearsagobutgotnowhere.I’vebeen given strong

reasonswhyblackis compulsoryfortyres,butthere are plenty of

whiteonesat veteranbikeshowsandredonesonmultiple images

of the 1928 OpelMotoclub.It mightlookgimmicky, but it would

berefreshingto seesomeof thepossibilities.

Perhaps,thefinalstepwillbeairlesstyres,aspioneered by

Michelinforcars,jeeps,andquads(thoughI have yet to see a

motorcycleapplication).Thetyreis a matrixofflexible rubber

walls,witha smallmetalrimat thecentre,aboutthe size of a

currentdiscbrake.Ona motorcycle,thewheelitself would be

allbutinvisible,leavingusonlythetyretocolour or style. The

ideahasbeeninprogressforsomeyearsnow,so don’t hold

yourbreathona revolutiontoourridesintheimmediate

future.But,surely,afterallthistime,toquoteThe Stranglers’

lyric,Somethingbetterchange.

LEFT: BMW’s

cross-spoke

wheel places

the spokes

outside the tyre’s

pressured area

RIGHT:

FrancoSbarro

buildinghis

“OrbitalWheel”

motorcycle

concept

ABOVE: Single-sided

forks or swing-arms

allow a better view of

the wheel design

BELOW: Sbarro’s

“Orbital Wheel”

motorcycle of

1989

LEFT: Multiple

functions,

including brake

and chain

carriers, can be

included on a

single casting

LEFT: The MV

Agusta Dragster

makes a feature

of the flange-

mounted spokes

BELOW: Airless tyres, like the Michelin

“Tweel” and others, have only a small

inner wheel

ABOVE: CNC
milling will
machine
whatever you
program into
the data

Next World Design “Apache”

from the early 1990s

Of course, with designs like

this, it doesn’t matter what

the wheels look like

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Yamaha

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Sbarro

http://www.bikeindia.in August 2019 BikeIndia (^45)