R75/7 R100/S Road Test
Motorcyclist Illustrated April 1977
Tucked away just off the Bath Road in Slough
is a motorcycle shop. It hasn't got any big
glass fronts or gaudy neon signs. In fact, if
you didn't know it was there, you'd probably
never notice it as you flash by to or from London
on the A4.
It's just a little blue and white converted
cottage, resolutely defying any attemp to recognise
the chromium-plated superbike age. It belongs
to Chas Coombe, a BMW dealer for more years
than he cares to remember: one of the originals.
Concessionaires, importers and hyper-salesmen
have come and gone. But Chas is still there,
literally minding his own business, and will
be long after the others have returned to selling
sports cars and washing machines.
Chas doesn't sell that many BMWs these days.
He could. But he prefers not ot. He spends a
lot of his time working on bikes for the Thames
Valley Police. But he's also been carrying on
a sort of one-man rearguard action against the
trend new motorcycles have taken. He's
never quite forgiven BMW for dropping the R69.
I first met Chas about half-a-decade ago not
long after I joined one of the weekly comics.
As a fresh, bright-eyed young journalist I was
a little overawed by being sent out to collect
one of the recently introduced R75/5 BMs for
Chas soon brought me down to earth. He didn't
reckon it was a real BMW. Not a proper one anyway.
Not like the ones they used to make, or the
ones they could still make, if only . . . Well
we all have to learn to face new things. Though
we don't always agree with way they turn out.
But Chas Isn't just one of these people who's
always harping on about the old days. He's just
got very particular ideas on his motorcycles.
And they make a of sense. In fact, the more
I think about them, the more sense they make,
whether by long experience, or just an awareness
of the natural order of things. One of the prime
rules, for example, is that you should always
mount a motorcycle from the left hand side,
like a horse. And there were plenty for rules
that applied to BMWs especially. For instance,
the approach to the parked vehicle.
You should never sit on it and push it off
the stand. You first lean over it, roll it off
and swing your right leg across, remembering,
of course, to give the mainstand spring a little
urge with your toe. It's particularly important
to do that from the side after the first few
months of a new bike, when the little metal
prong has broken off, and you have to hook your
foot right underneath. It's little touches like
that which are reassuringly similar about all
BMWs whatever their age, colour scheme, or specification.
There's no other marque which manages to retain
so may quaint idiosyncracies in its pedigree.
Chas taught me most of what I know about those
mysteries. How to use the clutch and change
gear properly, how to deal with brakes that
always squeaked, and tappets that always rattled.
The sense of what he said is as true and familiar
now as I reflect on the 1977 BMW/7 range as
it was then when I collected my very first 750.
Eight models and 40,000 shaft-driven miles
further on, it's hard to avoid the summary that
the most striking thing that's changed has been
the price. With another speed in the gearbox,
and a disc brake on the front, this year's 750
cost just a thousand pounds more than the one
I rode five years ago, and the new top model
of the range, fancy fairing, instruments and
all, almost a thou more again.
BMW pulled off something of a coup with their
RIGORS (remember to keep these letters in the
right order or the next few pages will get confusing),
with its wind tunnel designed integral streamlining,
ergonomic cockpit, 18 per cent better time keeping,
and yes, I know, you've read all that before.
BMWs sales drive, based on their pride of the
line has rather overshadowed the 1977 models
of previous range leaders, the updated 750 and
uprated R100S (which has superceded last year's
There are a host of detail changes to both
bikes, as well as more subtle cosmetic changes.
But the most obvious difference is the move
up to a full litre on the top models. This has
been achieved by stretching the bore out 4mm
to give an actual capacity of 980cc, a simple
enough move, but the resulting oversquare power
unit is radically different from it's fire-eating
Instead of increasing out and out performance,
the consequence is been altered as perfected.
There was never a great deal wrong with the
750 BMW. It did need five speeds to keep in
line with the performance of its contemporaries,
but problems with the earlier boxes left
the gear change generally stiff and more temperamental
than even the legendary clunk-click machine
The new cluster is just perfect. In fact the
750 I rode had the best gearbox of any BMW I've
known as far as smooth selection goes. Tshe
secret is to feel your way through, but forcefully,
without fear of dramatic noises. They're just
there simply to inform you the dogs have connected.
On previous models a shy toe could result in
incorrect meshing, and all sorts of nasty
complications. The new ones seem fuss free,
and relatively foolproof. One up for progress.
The single front disc with its floating caliper
and perforated surface is also by far the best
arrestor of any current motorcycle for its combination
of adequate stopping power and maximum feel.
What it loses in absolute force to twin discs,
it gains in precise control at the fingertips.
And those engaged in lengthy debate on the efficacy
of discs on two wheels would do well to chew
on this one before pontification. Gentlemen,
we have the technology ...
BMW's system of a cable operated handlebar
lever leading to a master cylinder out of harm's
way beneath the tank loses no efficiency for
its extra mechanics.
Moreover, I felt much happier with the single
disc on the 750 than I did with the twin setup
on the 1000. In comparison, they felt very spongy,
and did not inspire the same trust and predictability
in regular use.
Among the many internal improvements to the
big, flat twin engines, attention has been given,
to one of BMW's nagging failures, oil seepage.
This either causes excessive oil consumption,
or a fine mist appearing on external surfaces,
especially at the base of the barrel.
The driving force for these gushers is crankcase
pressure. BMWs have a relatively small wet sump
capacity — just 4 pints — and lubrication
is consequently fed with some power to ensure
comprehensive circulation. As a result, a small
leak is liable to become a big one. However,
new '0' rings at the stem of each pot, and improved
crank- smoother torque curve which has completely
flattened the great power step that used to
launch the 900 forward like a demon. Gone is
the thumping power of the old 'S', it is more
lazy and less exhilarating, and rather mimics
the characteristics of its smaller stablemate.
My immediate reaction was one of disappointment,
verging on nostalgia. While a lot of other things
make the R100S a nicer bike, it has rather lost
its spirit, in the same way it has relinquished
its flamboyant two-tone colour scheme. The paint
work is immaculate, but the dainty gold trim
line on the tank is a poor substitute for more
exotic metalflake. No, they don't paint 'em
like they used to.
Instrumentation remains basically the same,
the small cockpit fairing concealing a voltmeter,
and almost certainly the most valuable addition
to the dashboard, a clock. I can't understand
why, of all those gadget-minded people in the
accessory business busy bolting on other goodies
to standard road machines, no one else has seen
fit to market a timepiece. Far from a fruitless
status symbol, it is a constant boon to well-wrapped
wrists, with inaccessible watches.
With typical teutonic thoroughness, it is quite
reliable, and runs of course, independent of
the ignition. In addition to the cockpit console,
the R100S retains the same rev counter and speedo
as all models, together with neutral lamp, main
beam and flasher indicators, generator warning
light, and the extraordinarily excessive one
marked ominously 'brake failure'. This meters
the fluid level in the master cylinder, although
its label looks disconcertingly dramatic.
That, in any case only applies to the twin
discs at the front, with the bike sticking faithfully
to the perfectly powerful and predictable
The final point of distinction is the nicely
shaped dual seat, with a rear hump concealing
a handy storage area underneath the tail. This
seating accommodation is one of the fruitful
advances, though the side folding fittings,
which never quite seat fully, remain. This means
that unless, like a hardened BMW traveller,
you pack the underside with something like an
oversuit, it will probably rattle a bit. Obviously
they only put them in a wind tunnel front first.
In comparison with the rather detuned S, the
R75/7 has not so much case ventilation may have
worked the trick. Certainly neither test bike
showed any external wounds, and oil consumption
Also inside there are modified rocker arms,
higher tolerances on the valve springs, and
lighter aluminium tappets, all of which result
in smaller valve clearances, and consequently
a quieter note from a traditionally 'tappety'
engine. The finning on the barrel is also
shorter and thicker, again helping to reduce
resonance. They don't sound quite like they
used to either.
The handlebar switches have again been modified
because of criticism that previous ones were
too fiddly to operate properly in action. What
they've done is to add a wing extension to the
up-and-down thumb controls either side. On the
right, the indicators, the other the lights.
Unfortunately on both my test bikes, I found
more difficulties than before. The dip switch
went down fine, but flicking up again to main
beam proved awkward, and tended to jam, while,
on the other hand, great care was needed after
turning to prevent switching from one indicator
to another. The performance of the lights when
selected however, was excellent.
For some reason BMW have a tradition of eccentric
key design which began back in the old Bosch
toggle days, and the current offering maintains
the line. The shaft is conventional enough,
but with a folding head, it is tricky to handle,
unnecessarily awkward to use, and impossible
to insert in the seat lock.
That is particularly unfortunate because without
security the tool tray with its immaculate 23
piece set and roll, puncture repair outfit,
and handpump are all prey to prying fingers.
The seat, if locked, also serves to secure the
simple but effective helmet holder, so it is
I can vouch for the tool kit as I have actually
once seen and used one in the past, though it's
a sad comment on the declining standard of motorcycle
journalism that BMW evidently no longer
trusts to send its test bikes out with such
a tempting and removable selection.
BMW also, for some reason, seem to have lost
the ability to make petrol caps. The ones on
the last models kept popping open at the
most inopportune moments. Perhaps in frustration,
they've now abandoned the concept and merely
borrowed what look like stoppers for oversize
hot water bottles. Flush with the tank, they
are difficult to get out, and impossible to
tighten on a large thread. Forget any ideas
of a tank bag unless you don't intend to refuel.
On the external side of the engine, noticeable
changes are the streamlined rocker boxes in
matt black, surmounted by monster rubber suppressor
caps. The R100S also has new 40mm Bing carburettors,
and while these pose yet an increasing hazard
to the shins (padded boots are advisable), they
give an impressive performance, and have
ironed out a lot of the more erratic breathing
of the 90s. Cold starting with the beefed up
starter motor was reliable — just as well
as they've long since abandoned the kick start
you couldn't kick anyway. A brief warm up, and
a certain hesitancy for the first mile or so
was the only demand made upon the throttle.
Such is the smoothness of the new R100S power
that you can't really tell it from the 750 'til
you get up over 5000rpm. Then the torque shakes
the mirrors to a blur before it eases out to
a gently throbbing 4000 to give you your legal
limit cruising speed.
The power in hand above and beyond that is
the main clue to the near full litre power source
you're sitting on. But it never surges, it just
rolls on and off.
Handling of the 750 was impeccable, and tuned
to its slightly less momentous power. What you
don't have in sheer horses, you can maintain
by keeping the motor turning and letting the
finely balanced frame and suspension do the
The R100S however, despite its smooth power
band, proved to be even more a handful than
the R90S used to be. More, perhaps because of
its deceptive nature. It was not so well
disposed to change determined direction, and
more inclined to wave its head over the bumps.
Disconcerting rather than actually dangerous.
You'd never quite lose control of a BMW, it
just keeps you very wide awake.
Perhaps in its relative instability, it proves
the claims for the more futuristic RIOORS, and
the exotically sculptured full fairing. If the
aerodynamics of the RS keep the front wheel
more firmly on the ground, if only by the standards
of the S you can judge it, and the case seems
creditable. Although it has 5bhp less, the S
is a little lighter, and a shade quicker than
the RS, but it has perhaps the speed at the
price of security.
And unlike the RS, it doesn't have a steering
damper, a device which has always been of uncertain
value to BMW geometry, and at times a positive
What you do get is a bike with a top speed
of around 118mph, which will do a standing quarter
mile in 14 seconds and average about 45mpg.
The 750, in comparison will take about
16 seconds to cover the distance, and levels
out at around 104. Reasonable performance figures
without being sensational.
And that is perhaps BMW's hallmark. The RS
apart, there is nothing that sensational
about BMW's new range. Nothing in fact that
hasn't already been remarkable about these machines
for many years.
In many ways some of the additions and alterations
have rather gilded the lily of an extremely
well thought out and excellently engineered
motorcycle. It's just sad that the gilding has
been at such a cost that the secrets of how
extraordinarily enjoyable motorcycling
can really be will be reserved for a privileged
BMW R100S (R75/7) Specifications
- Engine: 980cc 94 x 70.6mm
(745 cc 82 x 70.6mm) horizontally opposed
flat twin. Overhead valves 44mm (42) inlet.
40mm (38) exhaust. Light alloy cylinder heads
and barrels. Cast iron liners. Two plain main
bearings. Plain big ends. Wet sump lubrication
capacity four pints with replaceable paper
filter. Two 40mm-choke Bing constant velocity
carburettors, with cable-operated cold
start jets. Paper element filter. Compression
ratio 9.5 to 1. (9 to 1). Claimed power max.
65bhp at 6,600rpm. (50bhpat6,200rpm).
- Transmission: Dry single-plate
clutch mounted on crankshaft. Helical gears
to five speed box. Ratios: 4.4, 2.8, 2.1,
1.6, 1.5 to 1. Shaft final drive ratio 2.9
to 1. (3.2tol) No kick start.
- Electrics: Coil ignition.
12 volt 28 amp-hour battery. 240 watt (280
watt) alternator. 7 in diameter headlamp 60/55
watt main beam. Five fuses. Electric start.
- Brakes: Cable and hydraulically
operated twin front discs (single). 1014in
dia. 7% in drum rear.
- Tyres: 3.25 x 19in front.
4.00 x 18in rear.
- Suspension: Telescopic
front. Hydraulic and spring rear with three
- Wheelbase: 5814in; seat
- Height: 3H/2in (30y2);
- Curb weight: 480 Ib (460
- Fuel capacity: 5*4 gallons
including 5 pint reserve.
- Price: £2,659 inc