digitaLmbuL’s FiLes

This site originally started out as being just for cars, but as I also
ride motorbikes, I felt I had to include information for the bikers out
there too.
Here then is the Suspension Bible : Motorcycle edition.
Oh – a little note – the reason I switch back and forth between motorbike
and motorcycle is simply an internet thing. I’m trying to make the page
more friendly to search engines for people looking for both words :
motorbike and motorcycle. That’s all…..
A little background.

Motorbikes, or motorcycles if you’re American, have a similarly varied
selection of suspension systems as cars. On bikes, of course, you only have
two wheels, so bike suspension systems tend to be a little more highly
engineered because there is more at stake. By far the most common setup now
is the single rear coilover shock system with either a regular double
swingarm or a single-sided swingarm. At the front, telescopic forks are
still the most prevalent. It’s surprising that there’s still a large number
of cruisers out there that are ‘hardtail’ bikes – bikes where there is no
suspension at the back. The wheel is simply axled straight on to the frame.
This is a throwback to the very first motorbikes which were basically
bicycles with an engine strapped to them. (In the 1920s, motorbike
suspension consisted of the springs in the saddle and the air in the
tyres.)
Motorbike suspension geometry 101.

Before you dive into the murky world of technical terms which litter the
rest of this page, it’s worth knowing up front what some of them mean in
relation to the way motorbike suspension is set up. This little diagram,
then, explains the basic terminology you’ll come across.
[bike suspension geometry]

Sports bikes typically have less rake which means less less trail. Less
trail means less stability, which means a quicker-steering bike. This makes
these bikes a lot less stable to ride in a straight line, but a lot more
flickable in the corners. Conversely, cruisers, choppers and customs, have
much more rake. More rake means more trail, which means more stability,
which makes the bike harder to turn. This is why Harley Davidsons are
typically a bitch to get around a corner. However, bikes with more rake
work better in a straight line, which is why bikes like the Honda Goldwing
and BMW LT series have more rake – they’re designed to be long-distance
cruisers. It’s worth noting that when I talk about more and less rake, it
can be within 5° For example the difference between a flickable Yamaha R1
race bike and a BMW K1200LT cruiser is 24° and 26.8°
Anti-Dive forks.

One of the drawbacks of telescopic forks on a motorbike is their tendency
to compress under braking, making the bike ‘dive’ forwards. This is due
mostly to the steering geometry of the average motorbike. When you brake,
you’re slowing the forward motion of yourself and the motorbike. That
forward force has to go somewhere, and that somewhere is the front
suspension. Because the telescopic forks are at an angle to the frame, and
consequently at an angle to the braking force, some of that forward force
gets sent directly down the forks.
[force][force]Think back to your school physics. Force transmitted at an
angle is equal to the main force multiplied by the cosine of the angle.
Remember the rake on a motorbike is calculated from vertical. So the angle
we want is actually 90° minus the rake – the complement of the angle.
Conveniently, because sine and cosine are the inverse of each other, the
cosine of one angle is the same as the sine of its complement. So for a
bike with a rake angle of 25°, we can either use the cosine of its
complement (65°) or the sine of the rake angle itself.
Look at the diagram on the right; if the rake angle of our bike is 25°,
then the force down the leg of the forks is (braking force) x sin(rake
angle). For the sake of getting a number, lets use a ridiculously low
braking force of 1 newton. That makes our calculation (1) x sin(25) which
is 0.4226, or 42.26%. So 42% of the forward force generated while braking
travels down the fork legs into the springs and fork oil.
To put a real world number on it, lets say you weigh 100kg, and your bike
weighs 165kg. Force = (mass)x(acceleration). Jam on the brakes and you
could easily generate a deceleration of just under 1G in an emergency lets
say 9m/s². In that case, Force = 265Kg x 9m/s² which is 2385N. If 42% of
that zips down the fork legs, your springs and fork oil are suddenly
dealing with around 1000N – about 100Kg of force. In short : you have just
transferred your entire body weight into the forks, which is why they dive.

[anti-dive on a GPZ900R]Honda fired the first shot in the anti-dive war in
1969 with the introduction of its TRAC system (Torque Reactive Anti-Dive
Control), but it wasn’t until the eighties that it became more mainstream.
Anti-dive systems were typically linked to the brake hydraulic system, and
is remembered best on the Kawasaki GPZ900R where it was introduced under
the moniker AVDS – Automatic Variable Damping System. AVDS was a
supplemental hydraulic cylinder mounted on the front of the fork legs which
was connected to both the brake lines and the hydraulic fluid inside the
telescopic forks. The idea was that as you applied the brakes, this unit
would use the pressure in the brake line against a plunger to close a
control valve. This valve restriced the flow of fork oil and thus stiffened
the suspension. Stiffer suspension meant less dive. Anti-dive units mostly
featured a dial adjuster on them, normally at the base. This was a way of
affecting how much the anti-dive plunger moved, which meant the rider could
make the anti-dive more or less severe.
It all sounded good in principle but a lot of riders took a dislike to it
because of its behaviour on bumpy roads. If you went to brake on a bumpy
surface, the front suspension stiffened up and it became less like riding a
motorbike and more like falling down stairs as all the road bumps and
deformities were transmitted up the now-stiffened suspension into the frame
of the bike, and consequently, the rider. The control valve would often
stick closed resulting in permanently stiff suspension, which in turn would
result in frequently blown-out oil seals. These “features” of anti-dive
systems have since been ironed out and they tend to work maintenance-free
now.
TRAC

The Honda TRAC system differs somewhat from the ADVS-style units. Honda
maintain that hydraulic systems have two basic drawbacks. First, the
additional brake-line plumbing and increased brake-lever ratios can produce
a spongy feeling at the brake lever. Second, those systems are either on or
off – there’s no modulation of antidive effect. To get around these
problems, TRAC is instead activated through the torque reaction of the
brake caliper itself. This makes it completely independent of the
hydraulics in the brake system. It works because one of the two front brake
calipers is hinged behind the fork leg on a pivoting link, rather than
being solidly attached. When you apply the brakes, the pads grip the
spinning disc and this tries to drag the brake caliper around with it. The
caliper pivots on the link and presses against the anti-dive activating
valve which is built directly into the fork leg. From then on it, it works
just like the Yamaha and Suzuki systems, restricting the flow of fork oil
and stiffening the suspension. The advantage of the Honda system (they say)
is that the harder you brake, the more pressure the pivoting caliper puts
on the control valve, and the stiffer the suspension gets. One important
difference with TRAC is its ability to deal with the bumpy road surfaces
which the other systems had a problem with. The TRAC valve is a floating
piston held in place by a spring. This means that if you hit a bump, the
sharp and sudden increase in the pressure of the fork oil can override the
anti-dive valve and force oil through the valve as if it were not applied.
This means that TRAC can respond to bumpy roads whilst braking. Clever eh?
Headshaking, tankslapping and steering dampers.
[steering dampers]

As I mentioned above, if the rake a telescopic fork is set just right, you
get a bike which has very quick, precise steering, but becomes
fundamentally unstable at low speed. This isn’t normally an issue because
sharp steering is found mostly on sports bikes, which tend to travel pretty
quick. The problem comes when you hit a sufficiently large bump. The front
suspension compresses, the wheelbase of the bike gets shorter and suddenly,
what was on the cusp of driveability becomes totally unstable. The front
wheel will tilt to one side or another and then the suspension returns to
its normal length. As it does this, it sets up a standing-wave in the
chassis of the bike which, because of the gyroscopic forces generated by
the front wheel, forces the steering over the other way. Now the suspension
geometry and gyroscopic force of the spinning wheel together try to
straighten the front wheel again. At this point, the bike is in a
headshaker – the head of the bike is being shaken back and forth by a
rapidly oscillating front wheel. There are ways and means out of this, but
if you don’t tackle it quickly, things will rapidly go downhill. The
headshaker will get more and more violent because now, the wheel starts to
slam back and forth from one side to the other. The handlebars will get
ripped out of your hands and the steering will go from lock to lock very
quickly, slapping the handlebars against the tank of the bike – hence
tankslapper. The inevitable outcome of this is normally a highside where
the bike will throw you off sideways and upwards. Once you’re off, the
suspension unloads, the bike settles down, and momentum will take its
course as the bike drives off in a straight line without you. This is the
reason for steering dampers, and one of the reasons the Suzuki TL 1000S was
recalled within weeks of being put in the showrooms – it went into vicious
tankslappers without any provocation.
Steering dampers, therefore, are A Good Thing if you are going to be racing
or owning a bike with suspect handling. They come in two basic forms -
linear and rotary. Linear dampers are literally a long cylinder with a
clamp on it and a hydraulic ram with another clamp. One end gets attached
to the front forks of the bike, the other to the frame. They look like mini
shock absorbers and are designed to be virtually unnoticable under normal
circumstances (in terms of steering stiffness) but if you get into a
headshaker, the rapid vibration can quickly be cancelled out by the damper.
On the right here, the top image shows a linear damper attached lower down
the forks, and to the frame. The second image shows one mounted across the
steering head, attached to the tank and the top yoke. The third image, at
the bottom, shows a rotary damper. These are still pretty new at the time
of writing, and are normally not available as aftermarket items. (There are
some around but what I’m saying is that they typically are designed into
the bike from the factory). Rotary dampers sit at the top of the head
bearing, either above or below the top yoke, and use either a rubber
friction bearing or a hydraulic system. The outer part of the damper is
attached to the frame, and the inner part has a splined hole through which
the steering head shaft passes. The rubber or hydraulic system sits between
the inner and outer sections so that if the bike gets into a headshaker,
the rapid oscillation of the steering head shaft causes the splined
internal part of the damper to try to spin from side to side. The outer
part is solidly attached to the frame and the friction medium in between
the two damps down the oscillation. Or to put it more simply, stick your
left forefinger out and grasp it with your right hand so as to make a fist.
Now twist your left hand and voila – rotary steering damper 101.

Motorbike suspension – front end.

Today’s modern telescopic fork front suspension systems are basically the
current evolution of something called a ‘girder fork’. This was one of the
earliest attempts to control the front wheel of a motorcycle but it has one
serious disadvantage : as it works through its limits of movement, the
effective wheelbase of the motorbike continually changes. Hit a bump, the
front wheel moves up and back relative to the frame, and the wheelbase is
shortened. Shorter wheelbase means less stability at speed, which is one of
the reasons that if you’re unlucky enough, you can get into a tank-slapper
on almost any modern motorbike.

Check back shortly for a breakdown of the different types of front-end
suspension. In the meantime, feast your eyes on :
Motorbike suspension – back end.
Twin-shock, regular swingarm

The classic motorcycle suspension system. An H-shaped swingarm is pivoted
at the front to the motorbike frame. On either side there are basic
coilover units which provide the suspension. The shocks are inside the
coilover units. This is about as basic as you can get on a motorbike and
has been around for as long as the motorbike itself. This style of
suspension began to fall out of favour in the 80′s due to weight
considerations and the availability of newer, stronger materials. It was
also not a particularly robust design by modern considerations. It all got
a bit bendy and flexible under extreme riding conditions, and the only way
to make it stronger was to add more metal, which added more unsprung
weight, which reduced the efficiency of the suspension.
     [rear swingarm]
[monoshock]
Monoshock, older style, regular swingarm

In 1977, the first monoshock system appeared to niche markets and racers.
It has actually been around in one form or another since the 1930′s, but it
was only in the early 80′s that monoshocks started to appear on production
bikes. Monoshock is actually a Yamaha trademark, but it has become
synonymous with the design in the same way as people in the UK refer to
vacuum cleaners as hoovers. (The Honda version is called Pro-Link). The
premise was that manufacturers could save some weight by redesigning the
rear suspension and removing one of the coilover units. Monoshocks are
still coilovers, but there’s only one and it’s mounted centrally to the
swingarm. On earlier models, the rear swingarm was a sort of basket with a
linkage at the top-front. The monoshock sat nearly horizontal in the bike.
Monoshock, newer style, regular swingarm

On the current monoshock designs, there is now a complex linkage at the
bottom end which joins the coilover to the swingarm itself, and its
important to lube the joints in these linkages regularly. They are very
exposed to the elements when riding. The linkage adds leverage to the
suspension plus it allows the coilover to be mounted more vertically. Ever
in need of less weight (and hence more speed), those clever engineers who
devised this variation were able to remove the ‘basket’ part of the
swingarm, and revert to the traditional “H” shaped arm, only with a bit
more welding here and there and stronger materials. Hover your mouse over
the image to show a closeup detail of the linkage. You can also download a
small Quicktime movie (245kb) in a popup window of this linkage in action.
You’ll need Apple Quicktime 7 for it to display properly as I have used the
new H.264 codec for quality.

.
[single-sided swingarm]
Monoshock, single-sided swingarm

The ultimate evolution of the monoshock design is the single-sided
swingarm. These are super-strong, super-lightweight swingarms like you
might find on a VFR800. The advantage of a single-sided system is that the
wheel can quickly be taken out and replaced. Not really a huge advantage
for you or I fiddling with our bikes at the weekend, but for Moto-GP style
racing, it does make a huge difference for the pit crew. Single-sided
swingarms need to be pretty heavily engineered because they bear the all
the stresses from the rear axle offset to one side. With the traditional
double-beam swingarm, the design needs to have longitudinal stiffness to
stop it from bending. With the single-sided design, it needs to also have

torsional stiffness to stop it from twisting under the offset load. As a
result, single-sided swingarms are typically a lot larger and have a huge
amount of cross-bracing inside them.
One shock or two? The frothy subject of frappuccino damper oil.

single vs doubleIn the good old days, motorbikes had two shock absorbers on
the rear of the bike, as shown at the top of this section. As suspension
evolved, the dual rear shocks were replaced with a single unit, but the
question is why? The answer, it turns out, is pretty simple. In a
dual-shock system, the suspension units are typically attached very close
to the rear axle. This means that as the suspension compresses and expands,
the shock absorber pistons are travelling in a stroke which is nearly the
same as the full deflection of the swingarm. Hitting a large bump might
deflect the rear axle upwards by 10cm and back, resulting in the same 10cm
stroke in the shocks. Do this a lot and the shock absorber piston begins to
behave like the plunger in one of those natty little cafetières or
milk-frothers – it agitates the damper oil so much and so frequently that
the oil begins to heat up and foam or froth. At this point it not only
looks like frappuccino foam but it has about the same damping properties
too, and thus loses its ability to perform as it should. This is known as
fading shock absorbers.
Enter the single shock absorber system mounted towards the front of the
rear swingarm. The swingarm might still have a lot of travel at the axle,
but basic geometry shows you that closer to the pivot, the deflection is
much less. This translates into shorter shock absorber movements which in
turn means less opportunity for the damper oil to froth. The ultimate
evolution of this is the complex link monoshock system (also shown above),
where a complex series of levers reduce the shock absorber travel even
further. Typically multi-link setups like this also have some amount of
variance in them so that they have a different amount of deflection in the
first part of the stroke to the that in the second. This means a single
shock absorber unit can respond better to changing road surfaces, soaking
up the smaller bumps and shocks with ease and comfort without sacrificing
the ability to respond to the occasional mountain or pothole.
As a side note, you’ll notice as you read the section on BMW rear
suspension below that the monolever and first-generation paralever had a
single shock but it was mounted close to the rear axle. This had all the
disadvantages of a dual-shock system without any of the advantages of a
single-shock system. For the second-generation paralever, the shock was
moved closer to the swingarm pivot, thus bringing the design in-line with
the small-deflection idea.
The eBay problem

BMW logoBayerische Motoren Werke: those teutonic Germans and their
incessant need to be at the pinnacle of engineering excellence. BMW are
responsible for a lot of developments in motorbike suspension – not just
the quirky ones. The first hydraulically dampened telescopic fork on a
production motorcycle (1937), the longitudinal swinging arm (’50s and
’60s), and the long-stroke high-comfort telescopic fork (1970). Because of
this, I’ve given them an entire section to try to explain some of their
innovations for which we should all be thankful.
Well perhaps not all, but those riders who have chosen BMW as their steed
of choice will know that their bikes have what could best be described as
some pretty funky and unconventional suspension systems. BMW, it seems, are
never quite happy with the status quo. Why use an existing design when it
could be bettered? Why settle for DVD when you can have Blu-Ray? Just
because a particular type of suspension system is favoured by the Japanese,
and sold on hundreds of thousands of motorbikes every year doesn’t
necessarily mean that its the best option. At least not in the eyes of the
Germans.
BMW have long been known for their ability to cast scorn the accepted way
of things, and pursue other, better methods of achieving the same result.
Whether their suspension systems for their bikes actually are better or not
I suppose is open to debate. Having ridden and owned a BMW with telelever
suspension, I can’t understand why its not used on all bikes. Conversely,
bullet bike riders will look at a BMW and see nothing but excess weight.
You can be certain of one thing with BMW suspension systems: they’re
different. Very different. So lets start at the back and work forwards.

Rear monolever.

In 1980, BMW introduced the world to the monolever suspension system on the
back end of their R80GS big dirt bike. Little did anyone know at the time
that it was a sign of the radical design changes to come. Most BMW bikes,
modern ones anyway, have shaft drive, so its a given on a beemer that one
side of the rear suspension is going to be pretty beefy because it has to
house the driveshaft and ultimately the rear drive. BMW capitalised on this
and with the monolever, they created a single-sided suspension system, much
like the Yamaha monoshock, but the shock / strut unit was mounted to one
side of the bike, rather than in the centre. The driveshaft ran down the
inside of the single-sided swingarm and into the rear drive. This design
helped eliminate the need for beefier engineering at the front of the
swingarm which would have been needed to resist the torsional load of
having the wheel mounted to a single-sided swingarm.
     [BMW monolever]
[BMW paralever]
Rear paralever, first generation.

In 1987, BMW improved on their design and introduced the paralever
suspension system on the back end of the new R100GS, a system which found
its way on to their K1 sports bike too.
(Note : This is an improvement of a suspension system originally fitted to
the Magni Sfida called Parallelogramo. It was also available as a kit for
Moto Guzzis in the 80s. Parallelogramo itself is a derivative of a
prototype suspension of the same type shown on the MV Agusta 500 in 1950)
Paralever uses the same basic principle as monolever but adds a lower
control arm to the mix and an extra pivot point between the main swingarm
and the rear drive. The effect is that the old pivoting swingarm now
becomes part of a skewing parallelogram system – in fact a geometric double
wishbone system just like in a car. This added lateral stiffness to the
suspension, but it also kept the rear drive at the same orientation
relative to the rest of the bike. Because of the extra link at the rear
drive, the strut / shock unit was turned over so that it was “the right way
up”, and it was still mounted to one side of the bike. Because the whole
system now acts as a double swingarm, it substantially reduces the change
of load response of the driveshaft. Using this type of suspension was also
the impetus for BMW to change to using the engine as an integral stressed
member of the frame, which allowed the swingarm and suspension components
to be bolted directly to it.
Rear paralever, second generation.

In 1993, the second generation paralever system appeared on the R1100GS.
The basic design was the same as the original paralever except that the
strut/shock unit was moved away from the side of the bike and on to the
centreline, bringing it more in line with the monoshock type system. It
also gained a remote preload adjuster and spring
 plate height adjuster.
This new paralever was made of aluminium instead of steel so it was lighter
than the original whilst maintaining the strength needed for the
single-sided shaft drive system.
     [BMW paralever]
[BMW paralever]
Rear paralever, third generation.

Skip forward ten years to 2004 – which tells you how good the paralever II
was that its design didn’t change in nearly a decade. The third generation
paralever appeared in the new R1200GS. This design is similar but at the
same time noticably different to its predecessor, and at the time of
writing is now the current BMW rear suspension of choice. The control arm
was moved above the shaft drive from underneath, and the rear drive was
changed to have a hole through the middle of it to save weight. The
unsprung weight of the latest generation paralever is considerably lighter
than its predecessors. That’s not to say that it couldn’t still be used as
a substantial bludgeoning weapon if you got it off the bike, but in
engineering terms, it has slimmed down considerably.
Front telelever.

In 1993, when paralever II appeared on the R1100GS, BMW also introduced
their new telelever front end suspension system. The problem with
traditional telescopic fork suspension is that all the forces acting on the
front of the bike are transmitted to the handlebars, and thus the rider.
Some people think this is A Good Thing – it keeps the rider “informed” as
to what is going on. Others argue that it is a necessary evil and that
telescopic forks are an unfortunate accident of history (see the section on
forks above – it’s the same reason we got VHS when Betamax was the better
system). BMW fell squarely into the second camp, and developed telelever as
a method of separating the braking and suspension forces from the steering
force. With telelever, there is now a single strut/shock unit in place of
the combined spring/shock functions of telescopic forks. Telelever still
has front forks, but their primary function now is to make a stiff frame
for the front wheel to sit in, and to allow the rider to steer the bike
(which is always useful). The strut/shock unit is connected to a wishbone
which itself is connected to the frame of the bike at the back via a yoke,
and to the crossmember of the forks at the front using a ball joint. When
you hit a bump with telelever, the suspension forces are transmitted
through the ball joint, across the wishbone and up through the strut /
shock unit into the frame of the bike. One of the biggest advantages of
this system is that you don’t need to engineer an anti-dive system into the
forks. The design of the Telelever effectively reduces fork flex under
braking to near zero which in turn reduces dive under braking. Another
benefit is that the forces acting on the steering head bearings are
dramatically reduced. In fact with telelever, as a rider you have to get
used to the concept of braking without the bike diving at the front. It’s
really quite unique.
     [BMW telelever]
.

Front duolever.

Never being satisfied with resting on their laurels, by 2004 BMW decided
that telelever was yesterday’s news, and introduced duolever on the front
of their first inline-four sports tourer – the K1200S. I’m not sure, but I
think some of the BMW engineers might have discovered suspension nirvana
with this system as they now finally have double-wishbone type suspension
both front and rear. Duolever is an evolution of Norman Hossack’s double
wishbone / parallelogram suspension, which is why its sometimes referred to
as Hossack Suspension (see below). The idea itself has been around since
Hossack modified a Honda XL500 in 1979. In the early 90′s he modified a BMW
K100RS, and whilst it never really caught on in England, German engineers
understood the idea instantly. Like the rear paralever, its geometrically a
double wishbone system. As with telelever, in duolever the pivoting links
and springs are not steered. But with duolever, the physical link from the
handlebars to the suspension is radically different, involving a hinged
link. If you look at the image here, you’ll see the front suspension is
completely independent of the steering, with the two only being connected
by the hinged link up top. (That link is simply used for turning the fork
assembly and provides no structural support or strength). Hover your mouse
over the image for a close-up of the system. With the combination of
paralever III on the rear, and duolever at the front, sitting on and riding
a K1200S is unlike riding any other type of motorcycle. Whilst it may
technically be the current pinnacle of motorbike suspension design, BMW
have created a system which has divided riders into the love/hate camps.
A word from Norman Hossack himself

In early 2006 I was contacted by Norman Hossack himself to discuss some of
the pros and cons of motorbike suspension. I asked if he’d like to write a
“guest piece” for my page, and he jumped at the opportunity. Without
further ado, here is his contribution, which explains a lot about the
history of Hossack suspension as well as his frustration with the motorbike
engineering world at large, especially BMW:

open quotenorman hossack on his BMW conversion I set out to bring some new
thinking to motorcycle design. I had left McLaren with a wealth of
experience seeing how racing cars developed and how Formula 1 addressed
their technical problems. I was only a spectator in the motorcycle industry
and had no connections with it and still don’t; I don’t even ride a bike. I
do own the first Hossack BMW (see the picture on the right) but can’t ride
it where I live because the EPA think German carbon monoxide is worse than
American carbon monoxide.
Back in the mid 70′s, from where I stood, motorcycle design problems were
obvious and easily solved. Just improve the rigidity, lower the weight,
lower the polar moment, and kill stiction. So I did that and it worked, and
it won races and then it won again and again. Job done! No! I didn’t count
on the inertia and negativism in that industry. Seems perceptions are more
difficult to change than the engineering.
What has become known as the Hossack suspension system, I chose from a list
of about 5 designs options that I had invented. I assessed this one was the
one that my meager resources could do justice to. The other would have
required expensive tooling and structures and didn’t take things that much
further forward. I am not talking here about simple material changes;
making the same thing from aluminum or carbon fiber does not constitute a
new invention.
To look at the fundamentals of my design there are some first principal
elements to study.

   1. Lower weight. A bar bending between fulcrums suffers a pure bending
load. However if the load wasn’t strictly bending, but straight push and
pull, it could carry a load thousands of time higher. This higher value can
be exploited with triangulation. Race car wishbones are an excellent
example. These little devices can carry thousands of times their own weight
and have near total rigidity. Everything on my design is triangulated and
with that added strength you have a chance to save weight.
   2. If you were able to look down the axis of the steering on my design
you would see that the weight was quite close to the pivot axis. This means
low polar moment and this is important because most forms of weave are
sustained by this mass. The further it is from the axis the greater the
chance it can add to weave.
   3. Low stiction allows the tyre to ride bumps in with out being bullied
by the suspension this is where grip come from. You will commonly hear
commentators say ‘mechanical grip’ in F1 events and that’s what I am
talking about here.
   4. Tellies (telescopic forks) turn brake loads into dive, and dive
limits free wheel movement. My system doesn’t do that and allows full and
free movement even while braking. But more when a tyre is stopped too hard
and it loses traction, the energy stored in the front spring of a

---

telescopic system is suddenly released and it punches the tyre further
making the chance of regaining traction nearly impossible. Vernon Glasier
on HOSSACK1, my first bike, could readily slide the front wheel and still
regain traction.

So the fundamentals are there for discussion and challenge. But whether I
managed to get it right first time with only my meager resources is in
question. Though as a comment on my design it is worth noting that Hossack1
won its last championship in 1988 at which point it was 10 years old. Could
I have done better? You betcha! I never built a bike with a real race
engine and never found funding to do it the way it should have been done.
close quoteSo my attempt to revolutionize motorcycle design was a
nonstarter in the environment it was born in and I had to wait nearly
quarter a century to see the idea reach production (the K1200S) leaving me
out in the cold as patents don’t last that long.
I wonder when the next manufacturer will take it up and exploit the areas
that BMW didn’t.

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Speak!  ayah, pekerja, dan penggiat keselamatan jalan...

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