Bakker GSX-R F1 SB Road Test
The focus of experiments in alternative chassis and
front suspension design seems to have shifted from
France to Holland recently, what with the new White
Power 'Monofork', the Kawasaki-powered centre-hub
RB-1 that's so far been undefeated in Dutch National
TT F-Two events, and now the latest product from the
fertile mind of world-famous chassis constructor Nico
Bakker, whose small wooden shed of a factory employs
but seven people yet produces more than 120 frames
a year, for over 20 different types of engine. Bakker's
latest creation appeared unheralded in the paddock
at the Dutch GP at Assen, powered by a roadster VFR750
Honda engine, and caused tremendous interest on account
of its unique front end design and chassis-less construction
which appears to combine elements of both the ELF2
and ELF3/4, plus some original thought from its creator
and his colleague Cees Smit, a former GP sidecar driver
who assisted in the bike's design and construction.
A hint of the philosophy behind the new Bakker chassis
lies in its name: the QCS, standing for "Quick
Change System". "We were the first people
in the world to offer a single-sided, rear swingarm
to the public," says Nico. "And we've been
working on such designs for the past three years.
But what's the point of having a quick-change rear
end, if you then waste time in the pits changing the
front, because you choose to stick with conventional
twin-leg telescopic forks? This is obviously crucial
in endurance events, but GP bike racing is becoming
more and more like F1 cars, where people start the
race on soft tyres which give better grip, allowing
them to lap faster, but which won't last the distance.
That means they have to make pitstops to change rubber,
and though bike GPs are less than half the length,
I can see this coming to our sport as well. When that
happens, people like us and ELF are going to have
a big advantage, especially since race organisers
will be less disposed to stop the race if the weather
changes: they'll expect riders to come in and change
tyres if it starts raining, instead of the farce we've
just had here at Assen when they had to start the
race three times just because people kept getting
caught on the wrong rubber."
Grand Prix riders are a different breed than the
hard-nosed men of the endurance scene, and I'm not
sure I can see them taking lightly to a regime where
once the race starts it continues to its planned conclusion
come rain or shine — though come to think of
it, why shouldn't they, if only the bikes were built
in such a way as to facilitate tyre changes at both
ends?
So was this the only reason for Bakker's QCS design,
rather than an effort to probe the frontiers of alternative
suspension design in search of improved chassis response?
"Changing wheels quickly was the main reason,"
admits Nico. "But if you make a bike like this
then there are other benefits that come along, especially
speed and ease of adjustment of the front end geometry
and suspension settings, reduction in overall and
unsprung weight, and improved behaviour under braking.
Unlike some people, I don't think telescopic forks
are so bad, especially the modern 'upside down' type
like the White Power or Ohlins, because they've mostly
cured the problems of deflection and stiction we used
to experience, and they do give the rider more 'feel'.
But they are difficult to get at in order to fine
tune the suspension, and you do have this problem
with changing the front wheel. So that's why we made
the QCS."
The Bakker QCS imitates the ELF2 in having no chassis
as such, only a pair of aluminium subframes carrying
the wheels and suspension which are bolted to the
front and rear of the V4 Honda engine, which therefore
acts as a fully stressed member.
"The VFR is ideal for building a bike like this
because of its 'square' shape and the fact that it's
so strong — and heavy."
A single-sided rear swingarm, made from a special
grade of aircraft-specification alloy specially extruded
for Bakker in Holland (by Fokker??), is employed,
combined with a vertically-mounted White Power unit
whose system offers a rising rate. The swingarm is
hollow, though Bakker has experimented with an alloy
honeycomb filling to give an improved stiffness to
weight ratio. On the QCS, he says the extrusion is
strong enough without the added cost and complication
of the honeycomb filling. At the front, two large
alloy plates bolt to the engine and support an adapted
McPherson strut-type suspension system combining elements
of both the ELF2 and ELF3/4 designs, coupled with
Bakker's own ideas. Like the ELF2, the WP suspension
unit (a rear offering 4.5in of wheel travel or about
the same as a conventional tele fork) is mounted directly
to the 'chassis', with a strengthening strut to carry
the forces to the rear swingarm pivot. But unlike
the ELF, the QCS front suspension is operated by an
articulated triangle off the lower, and sturdier,
of three parallel drag links by means of which Bakker
aims to spread the forces generated by braking and
cornering throughout the chassis instead of at a single
point as with other designs. Yet with the exception
of the third drag link, located above the front wheel,
which adds to the overall rigidity o the front end
design, the rest of th< QCS is modelled on the
ELF3/4, wit the front wheel rigid on a vertical strut
(made from more extruded alloy), connected to the
steering head by rotating the base of the upper one
via an abbreviated steering column located in the
upp part of the front chassis sub-sectio
With a 57in wheelbase, a 23-degree effective steering
head angle (variable between 21 and 25-degrees) used
at present, and a 3.7 - 3.9in trail adjustment, the
QCS displays less radical geometry than other alternative
motorcycles, and its weight distribution of 53/47%
frontwards is par for the course nowadays, though
that figure is arrived at without the yet uncompleted
fairing, still to be fitted But by scaling 357lb with
oil, water, alternator and starter motor, the QCS
without fairing is a little over 10% lighter than
other bikes fitted with the heavy VFR engine, in endurance
trim, indicating one of the spinoffs of the Quick-Change
design.
More to the point, Nico Bakker estimates an endurance
race pit stop to take on 24 litres of fuel and change
both tyres should take no longer than ten seconds,
once a suitable means of jacking up both ends of the
bike quickly has been worked out. GP tyre stops —
here we come.
In line with the aim of reducing time spent in the
pits on this bike, Bakker has also fitted his own
make of six-piston brake caliper to the single 12.6in
diameter front disc brake, centrally located in the
17-inch wheel.
"We could have used a pair of four-piston Lockheed
or Brembo calipers but that would have been a compromise
in terms of weight, and positioning the second caliper
would have been difficult with this front end design.
So we made this six-piston caliper ourselves by casting
it up from magnesium in the shop, with the result
it weighs less than two four-piston ones, yet has
the same pad area. More importantly, the design allows
you to change the pads very quickly, within the time
of a regular fuel stop in endurance racing. However,
I'm aware that heat build-up has been a problem with
the ELF3, which employs a similar centrally located
single disc, and it may be we shall have to consider
another design once we start track-testing the bike.'
Amid the current controversy about GP tyre changes
and restarted races, maybe the QCS were the face of
the future
I'm also talking to Lockheed about using their rim
disc in an updated form, so long as we can change
the pads quickly. We'll see."
Completed only the day before Assen TT Week began,
the Bakker QCS will at first be run on the street
by its creator, using the roadster VFR engine presently
fitted. But track tests commenced in August with Boetvan
Dulmen at the helm, and the aim is to have the chassis
sufficiently developed to race in the Bol d'Orin September
with a kitted VFR Honda engine fitted.
Nico Bakker intends to market the QCS in 1988 with
both Suzuki GSX-R750 and Yamaha FZR750 engines fitted
as well as the V4 Honda, and a street version is already
planned which won't differ so very much from the endurance
bike. Smaller-scale QCS designs are also planned for
the 250 and 500cc GP classes, with RS250 and RS500
Honda versions already on the drawing board. Nico
plans to wait for Yamaha's 1988 customer race bike
plans to be announced before he makes any design for
their engines. Maybe in spite of all the publicity
generated by the various Elves and the Bimota Tesi,
this is really what the cause of alternative motorcycle
design has been waiting for: a small but active and
respected chassis constructor with a receptive market
and trustworthy track record whose faithful customers
are ready to buy what he gives them. And if he decides
that for all the practical, rather than theoretical
reasons in the world, that the time is ripe to make
and sell a chassis with something other than telescopic
':rks fitted to it, then perhaps its time has come.
First in the world to sell a bike with single-sided
rear suspension for the street or track; first with
a six-piston brake caliper on two wheels, Nico Bakker
may just also be the first in the modern era —
like Tony Foale, Norman Hossack and the rest of the
one-man shows — to build and sell a non-telescopic
forked bike to the public in measurable quantities.
Unless Honda's long-awaited ELF-derived roadster does
appear after all at this October's Tokyo Show.
This is a fairly typical story of how a new F-One
racing bike gets developed over the season. Glenn
Williams began the year with an unusual single swing
arm Nico Bakker chassis for his GSX-R jet after Assen
had abandoned the single rear arm and gone back to
a ranventional pivoted fork. The racetrack exposes
a lot of fine margins and weaknesses that couldn't
be apparent on the road and it took time for the team
to pinpoint the single swingarm as the Rely culprit.
Over the winter, the team counted their pennies and
decided to buy a new chassis. They went to see Nico
Bakker in Holland who showed them ts new racing designs.
Theirs cost a cool £5000 for the twin spar aluminium
fame, the RG500MMO forks, the swinging arm plus three
special QD rear wheels, the White Power stuck, the
seat, tank, yokes, brakes, wgsand everything.
By the time mechanic Alistair Janczuk had installed
the motor and transformed it into a racing projectile,
it really did look the business, immaculately crafted
and finished. In the paddock at Misano for the opening
F-One round, they were getting more attention than
the works bikes. The publicity angle is important
and keeps the sponsors happy.
Daring to be different was one of the reasons they
bought the Bakker chassis. Then there was the ease
of tyre changing during a race.
Unfortunately, this year the F-One calendar has gradually
lost its preponderance of road circuits (Vila Real
and Imatra cancelled and Ulster abandoned) and the
likelihood of changing tyres mid-race and still finishing
in the points has diminished.
Most F1 races are 100 miles long. There are only
two biggies — 150 miles around Misano and 226
at the Isle of Man. A quick tyre change could prove
crucial during the longer races and a QD rear wheel
is a neat facility to have in reserve.
At the bike's debut at Misano, Glenn finished 8th
after losing 40secs in a slow fuel stop. He'd been
impressed by how stable the bike felt on fast bends
yet had noticed serious rear wheel hop on the brakes
and through Misano's tighter, bumpier sections.
For the next round at Hungary, they lowered the gearing
and Glenn found the rear wheel hop more pronounced.
Why was it happening? The rear caliper is underslung
and attached to the swing arm tending to compress
the suspension under braking, yet the wheel was still
getting light, leaving the ground, then bouncing.
Less relevant though still odd was that the swing
arm pivot was below the drive sprocket's centre, so
with the suspension working, the chain was flapping
around.
The best solution seemed to be to tune the rear spring
and damping rates to overcome the worst of the hop.
Nico Bakker confirmed that a harder spring would cure
it though he must have known this ploy was at best
a compromise. Glenn never got to race in Hungary because
he was T-boned in practice and injured his shoulder.By
the TT in June, they'd uprated the White Power shock
and the bike was riding like a skateboard over the
bumps. The spring was way too hard. By bumping up
the spring they were effectively stiffening the rear
arm too and every bump was being hammered into the
rider's arms, legs and body. It was becoming a no
win situation. Either the bike was unrideable over
the bumps and on the brakes or you stiffened the suspension
so much, it was fine for the bike but too hard on
the rider. At the TT where Glenn finished 9th, it
was so uncomfortable it was dangerous to race it so
hard.
Over the phone, Nico was still recommending different
spring rates plus increasing the ride height. Glenn
thought the ride height was already way in excess
of what it should be. "Our whole back end was
very jacked up yet if you look at the works Skoal
Bandit Suzuki's they're very low and sleek. They even
file away the cases to stop them decking. If we raise
our ride height any further the engine will be carried
higher and so will the centre of gravity. It won't
be able to take S-bends or chicanes without wobbling
and it'll be quivering everywhere."
By this time, mechanic Alistair suspected that Nico
wasn't letting on everything he knew about his own
design. Practice at Assen was a disaster. Two rear
discs exploded into pieces (peppering the underside
of the ducktail). They'd been ordered in cast steel
but had arrived in cast iron. They'd overheated, warped,
then exploded. Having barely qualified, the Assen
fiasco was completed by a bad tyre choice for the
race. They fitted intermediates because rain looked
imminent but the track stayed dry and Glenn finished
a thread-bare and dejected 22nd.
They had plenty of time for a rethink. As a Kiwi,
Glenn was riding under a New Zealand licence which
this season meant that he couldn't race at British
national meetings only at full internationals. Living
in England and watching the rain come down while the
F-One races were being cancelled or abandoned meant
that by August he'd had but three proper outings.
Though he couldn't race, he did practice the bike
in an attempt to sort its handling/wheel hop/suspension
problems. The results of their testing was that they
abandoned the aluminium swing arm. For some time they'd
suspected that the rear of the single arm was too
heavy. The hub and housing carrying the dished wheel,
inbo disc and cush drive is in steel (t works Hondas
use titanium). It v strong enough but it was maybe
lOlbs too heavy at the back and weight was loading
up the suspension. At Assen it proved slower than
last year's stock-fra bike. After trying a dozen differei
spring and damping rates, they refitted the box-section
ali doubl arm. With the double swing arm, hop was
gone and the rear disc . no longer overheating.
After Assen, Alistair set about reducing the seat
height too. He revised the rear sub-frame, stealing
millimetres wherever possible. All in, he found two
inch. With the back end lower, they could even revise
the front, extending the fork tops to accomodate new
ban and provide a much happier riding position.
The steering head is adjustable and different shims
give a range of 22 to 26-degrees. The main aluminium
frame beams or spars a hollow but filled with a composite
honeycomb. Access is excellent. They can swop their
F1 motor for the full house GSX-R1100 lump in under
an hour. All up weight is 335lbs ready to race.
With everything sorted and much improved, Glenn will
be racing the bike with the 1100 mill (yet another
motor nicknamed Tyson') at the end of season internationals
at Mallory, Scarborough and Brands. You can also catch
it at the final round of the F-One WC at Donington
on September 27th.
Meanwhile, if you fancy a Bakker single sided, swing
arm chassis for the road contact David Brown Motorcycles
in Ashford (0233 27883). Conversion kits are currently
available for Suzuki, Honda and Kawasaki 750/1100s
and they've also got rather different frame kits for
900Rs, K100s, RG500s and Yamaha/Rotax 250s.
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