DESCRIPTION and THEORY
Norman was born in Scotland in 1946 but grew up and went to school in Umtali, Rhodesia.
He built his first bike from scraps when he was 12 a BSA Bantam. Later he owned a Greeves 196cc and later still,
his favorite memory a Ducati Mach 1 250cc. He also raced the Ducati for a season in Rhodesia
where he got the racing bug.
In 1969 he moved to the UK in time to see the TT that year and the racing bug bit deeper. Though he liked the TT then, he grew to dislike it and now thinks it's irrelevant.
In 1970 Norman mechaniced for Gordon Keith, a fellow Rhodesian and Manx GP winner. He did the European circus with Gordon and learned a lot. The following year he raced his own bike, a Greeves Silverstone 250cc with Bemsee and Southern 67 clubs.
In 1971 Norman started on his inventing career, designing and building a lobe 2 Stroke engine in which the piston crown and the connecting rod were combined. This engine ran well enough to push a go-kart but without funding it went no further. For a while he was known as the guy who invented a square piston engine.
In 1972 Norman joined Bruce Mclaren Motor Racing. During his 3 years with Mclaren he learned
much about race engineering
while building chassis, mechanicing on cars, pit crewing and coming up with solutions, earning him the
nickname Stormin Normin.
Norman ran the sister car but was part of the team that won the Indianapolis 500 in 1974 with
Johnny Rutherford. That year, Mclaren also won the Formula One world Championship with
Emerson Fitipaldi and the CAN AM series.
In the years that followed Norman did the Le Mans 24 hour race 3 times, the last 2 as race planner/manager.
In 1976 Norman began gathering ideas for his first bike HOSSACK 1. A model made from a coat hanger nailed to a piece of wood started the whole thing
The HOSSACK front suspension system consists of 2 wish-bones, an up-right and
steering linkage. Similar components are found on the front of all racing cars, the only
significant difference being in the up-right which has its geometry rearranged.
The wish-bones look and work exactly like their racing car equivalent The up-right performs the same task as its racing car equivalent but has its axle rotated through 90 degrees and over hung. There are few limits on how the up-right is made or what its made from, it could be fabricated, cast or layed-up. The steering link is a little clever though, as it has to pivot on roughly the same axis as the up-right. There is a handle bar pivot but this carries none of the suspension loading and only has to handle the weight of the riders upper half. Norman has run the spring/damper element in several different positions to achieve different conditions as is also common in the racing car world.
In all but HOSSACK 1, the up-right has been made of welded pressed steel profiles
making a very strong and light weight shell structure. Detailed stress analysis later showed
the up-right could not be made lighter even if it was made in aluminium, indeed an up-right
designed for a 125cc racer, made for destruction testing weighed under 1.5 Kg. Further
analysis done in Germany for the TUV approval which the HOSSACK BMW was
awarded, showed Norman got his numbers a little wrong because the axle structural stiffness was
25 times stiffer than a standard BMW (over kill)!
Before Norman left Mclaren he raced a 350cc Yamsel at club level. He found that when braking very hard
into Druids for example, the bike could be made to judder. This he attributed to flex and as it happened the
March Atlantic cars of that era did the same thing, leaving the familiar judder marks on the circuit at
the braking points. Norman was involved in chassis stiffness tests at Mclaren to investigate
the March problem and it was found that increasing the bulkhead
stiffness was the answer to the cars problem.
So Norman set out to stiffen up the front end of the motorcycle, his first design (1973) was a braced telly which he never built because it became clear that an additional and real weakness was the steering head structure itself. Just compare: the back end of a bike can carry:- most of the rider, a passenger and luggage on little bronze bushings less than an inch in diameter.
He knew that there had to be 'triangulation' in the structure, only that way could he achieve the stiffness to weight ratio he wanted. Wish-bones on bikes were GO. Norman drew several different designs but settled on this one. With this design, full triangulation was available therefore low weight as well as a major stiffness increase. Tellies back then were very flexible and no match for todays up-side downs (NOTE first seen on that little BSA bantam Norman started out on) but even the best telly could never come near the stiffness to weight ratio this design could achieve.
Note: once you have real stiffness inherent in A design you can both soften and direct that stiffness by using rubber bushings; the reverse is not possible.
GEOMETRY: Here the design opened up new opportunities that others could only dream about.
It was possible to juggle with these and even have:- non dive, anti-dive, or pro-dive or all 3 in one set up. It was even possable to imitate the geometry that tellies provide. By choice Norman ran the axle path near vertical to limit dive but here there is an introduction problem:- riders born on tellies can't get used to bikes that don't nod on braking, this is after all how they have learned how hard they are stopping. However after some exposure to this non-dive characteristic the gains become obvious.
Designed in mid the 70's from ideas worked out with a bent coat hanger nailed to a piece of wood,
the first parts were made just to test the function. Later Norman found wheels in a scrap yard and
made it movable so it could be pushed down a hill to see what it would feel like. Much later a
friend bought the project an engine, a Honda XL500. It took some cunning but Norman managed to
squeeze it into the frame and made it a runner. It ran first up and down the roads of
the Slough trading estate late 1979. It worked!!
At that time the only other innovation on bike front ends was the Defrazio system which
deserved much more credit than it got, and later came , the ELF fiasco which Norman blames for the
demise of the 'alternative suspension movement'.
Why? the question was asked could ELF with all their budget and influence not match the Honda they were up against in weight or stability. Answer "crap design", Norman doesn't have much better to say about the Bimota effort.
Next came some proper wheels from Tony Dawson : Astralites.
Eventually it became a racer, which it had to be if it was going to go any further.
It took time because Norman had no way to fund it properly and what funds there were,
were stretched to cover 3 patents at the same time. It showed
in Motor Cycle News in 1980 after it had been round Brands Hatch a few times.
It made an appearance on the BBC's Tomorrow's World in 1981.
Norman raced it in 1981 but it didn't attract much interest. Later a friend introduced Norman to Vernon Glashier who became its owner and then thanks to his skills, things began to happen.
VG won the Bemsee single championship in 1983 and in the same year the next
HOSSACK a 250cc Rotax engined machine won the Bemsee 250cc championship. Two out of two!
VG went on to win the British Single Cylinder Championship in 1986, 87 and 88 and set lap records everywhere. It won its last championship when it was almost 10 years old! Vernon retired it when the class changed to 600cc- a bigger engine would just not fit.
The frame design started with some observations then some theory.
Observation 1 - the Mclaren M23 had a front wheel weight of approx. 250lbs on each front wheel and the structure which held that wheel (top and bottom wish-bone) weighted approx. 3lbs and provided huge stiffness. Now the front end of a bike has similar weight but the forks are heavy and worse, they were not very stiff.
Note: Why this preoccupation with stiffness?:- answer the other side of the same equation is low weight! So Norman set out to design a system that could be triangulated and just as importantly symmetrical.
Observation 2 - essence of a good wishbone is that metal goes directly between the load points in straight lines, the curvy devices on the front of the ELF for example are not wishbones. Note : the ELF, the Yamaha and Tony Foales machines were all non symmetrical - this means more metal is required to achieve the same stiffness.
HOSSACK 1's frame started as tetrahedron, pyramid like but on a triangular base:-which is a
collection of triangles, the strongest possible geometry. One vertex became the steering axis, and
opposite axis at 90 degrees to it became the rear axle pivot. Next these 2 axis were stretched and tilted.
Then some engineering
compromises were required ; at the front some wishbones were needed and at the back
a swing arm pivot. The frame as a whole almost obeys Normans rules of what a wishbone should
be; the only compromises were that direct lines between the load points could not be achieved.
Still the frame design was good enough to win a championship 10 years later, so though Norman
claims he could have made it lighter there was no need. The bike weighed 215lbs in race trim,
the engine being close on half the total.
Norman managed to avoid the inventors obsession to rethink everything and stuck to the basics. "Inventors seem to have the compulsion to have a go at everything:-we have seen different handle bars, different steering geometry, different brakes, you name it". Norman kept it simple and used the known numbers and hardware where possible. Norman does not have fixed views on steering head angle;trail; c/g etc, all of these need to be tested and re-evaluated in the light of the extra stiffness the HOSSACK system offers.
After HOSSACK1 Norman built several other racing machines, though the closest he ever got to
a true racing engine was in the 3rd bike which had an RD350 Yamaha engine, this was his
favorite bike. This machine performed well in the hands of Ray Knight, Mat Oxley and
Alan Cathcart though they all complimented it and were competitive straight away nothing came of it.
Note: it's making a fine show for itself these days, 20 years later, with its new owner Steve Burge.
Norman did not initiate the change to road bikes, it just happened. Departing from motorcycle racing may
not have been a wise move but at that time there was no interest in racing machines, the market had dryed up. The
BMW conversions started before VG won all his championships and during a sour experience
with the MOD. A friend had crashed his K100RS, one of the first K100's in the UK, and
eventually Norman began converting beemers. These were more appreciated in Germany where most of them went.
The conversion work was considered of good enough quality by TUV to be
given their TUV approval. Though the BMWs worked fine they were the wrong bike to work on -
Ducati would have been a better choice but Norman never had the luxury of choice.
Norman is surprized and perplexed to find his design labled as a girder system. "Can it be these people have not bothered to look or do they lack technical savvy?" A simple look at the Hossack design will show that the system does not have a load bearing steering head as does a girder. The front steer axis of a girder system is fixed inexorably to the frame, whereas on the Hossack system this axis moves with the front wheel. The 2 systems do not share the same parts or geometry. In the racing car world where the idea was born, the parts were all familiar and the objectives understood, however this was new to the bike world where people either didn't bother to look at the parts or try to under stand their function.
Norman found enlightenment in Germany though, where people did understand the objectives. Motorrad magazine in 1993 compared Normans BMW K100rs conversion with a standard BMW K100, a Yamaha GTS1000, a TESI, and a BMW Telelever and found it technically superior.
BMW showed enlightenment too with their Telelever which came to market a year or two after Norman's/BMW conversions. BMW themselves tested more than one of Norman's customer bikes thoroughly and they understood the gains that a wish-bone could bring to structural stiffness. It was a step in the right direction though they stopped half way and kept the tellies. They also missed several other opportunities that the HOSSACK system could offer, namely, lower over-all weight, lower steer axis inertia, lower ride friction, lower manufacturing cost (the HOSSACK up-right does not have high percision parts) some additional geometry/ride options and the one sided option to match their rear end.
Norman's dealings with the MOD were unpleasant and here lies the seeds of his financial
collapse. The army bike showed another side to the HOSSACK system - the wheel can be one sided. The MOD bike had
a quick change wheel which potentialy could also have been interchangeable front to rear. For
enduro work it was possible to change the front inner tube without removing the wheel from the
bike. Further the front leg was a pressurized reservoir for inflating the tyre. It was even possible
for the bike to carry a spare wheel!
The bike was also featured on the BBC Tomorrow's World programme.
So these days Norman sells his services as a designer/inventor for a regular income and is always
on the lookout for interesting projects. There are no on-going Hossack projects that he is
willing to talk about.