OSSA 250 Monocoque

OSSA motorcycle

This amazing little OSSA 250cc Grand Prix bike finished 3rd in the 250cc World Championship in 1969. Its revolutionary monocoque stunned the Grand Prix paddock, yet the clearly superior design never found favour with the big manufacturers. Designed by Eduardo Giró, the son of OSSA founder Manuel Giró, the bike featured a six-speed gearbox mated to a single cylinder, 250 cc two-stroke rotary valve engine. It produced a modest 30 hp.

The engine was no match for the fire-breathing V4 Yamahas of Phil Read and Billy Ivy, but with its clever magnesium monocoque chassis, the bike weighed a full 20 kg (44 lbs) less than the class-leading Japanese competition. Riding the bike was young Spanish superstar Santiago Herrero, who soon showed the world that despite its power deficit, the advantages of the innovative chassis were sufficient to bring the small team Grand Prix victories. Herrero reveled in the OSSA’s superior cornering and braking ability, throwing the OSSA into corners like it was a 125 cc lightweight. He was able to carry more speed whilst being super-accurate, and slice up the inside of his competitors under braking.

It was all due to the monocoque’s superior chassis stiffness and weight. The 1969 campaign saw Herrero and the team win three Grands Prix against the previously unbeatable Yamahas and he led the Championship going into the final race—until a crash ended his title hopes. The tiny Spanish OSSA team again led the Championship in 1970, until Herrero crashed fatally at Isle of Man TT.

Devastated by his death, the OSSA team immediately withdrew from road racing, never to compete again.

  • jamie

    What a bold piece of engineering. It would have been fabulous if this bike had won the title in 1970. We may well have very different looking bikes today if it had.

  • http://www.car137.com Glenn Edley

    Fantastic piece of engineering and very forward thinking of OSSA.

  • Daz

    lovely

  • http://www.mulemotorcycles.net Mule

    Any race bike with a single cylinder gets my vote. Awesome chassis!

  • Michael Gardner-Smith

    If it was so superior why didn’t the design catch on?

  • http://www.mulemotorcycles.net Mule

    Many race bikes utilizing monocoque chassis have been built by privates and manufactureres alike since this bike shown here. The main problem is cost. Using Titanium, magnesium and carbon fiber are also “Superior”, but the cost would be huge, so that hasn’t caught on either except in MotoGP.

    Kawasaki had a GP bike with a chassis like this that Eddie Lawson rode. I beleive that one actually had an excess weight issue that caused handling problems. Also, can you imagine the liability nightmare of having the fueltank in the frame. Buell XB’s had that! If you crash or slide out, the first thing to start grinding is the fuel tank!

  • mingh

    shortlisted for bike of the year

  • Jon LeFors

    Kevin Cameron makes the point that the monocoque didn’t get wider adoption because they were / are so much more difficult to modify (especially in composite form, where the tooling is massive…) vs. the traditional tube frame. During this period where everything was evoloving all at once (Tires, brakes, etc), the frame might be different at every race. (His three books are amazing BTW.)

  • Sqizzla

    How many riders have been killed at the Isle of Man?

  • http://www.philaphoto.com Phil
  • Mike van Lienden

    Dick Mann told me he had a ride on this bike. He said it was a terrific package, repeating what the article says about handlilng and braking.
    It’s cool to see the overall package become greater thant he sum of it’s parts.

  • Turgut

    More recently, Kawasaki used a similar concept in its ZX-12R. A pressed steel upper frame has been designed to embody the airbox, also helping to place the fuel tank towards the center and lower under the seat. I say, the kawa zx12r is one of the most unusual bikes ever.

    Although the file name is not correct, you can see the partly-monocoque chassis of the zx12r in the following link. It’s from a website that compares the zx12r and the suzuki hayabusa, hence the file name is probably confused.

    http://image.sportrider.com/f/8579549/146_0110_06zoom+suzuki_hayabusa+chassis.jpg (kawasaki zx12r)

    http://image.sportrider.com/f/8579561/146_0110_07zoom+kawasaki_zx_12r+chassis.jpg (actually this is the suzuki, recognizable by the aluminum peripheral frame)

  • Carbon-arc

    What a great story, and what a pity that Herrero died. OSSA were right on the money with their frame design – just goes to show there is still little that is new these days

  • Mito

    This bike has everything, just so functional and different.
    I am an Ossa nut and this bike just screams at you, it is the pinnacle of single cylinder engineering.
    Very spunky bike .
    Ive got an early Phantom GP MX bike , so light and almost delicate, you start it up and you know they did this right.
    This GP in the picture must be just the nicest bike to ride?

    Mito

  • Mito

    BTW i am sure they put out more power.
    Will see if i can find a figure.
    GP MX were about 30+bhp

    Mito

  • Big Sven

    The aircooled engine put out 45bhp, the watercooled maybe 50bhp, but held it’s power better. Giro was a genius 2-stroke man, most underrated. He was hampered by lack of money and top-class materials, Spain had such import restrictions they were forced to only use recycled Spanish materials. Eyes boggled when they saw he was using a 44mm carburator – a HUGE carb for the day – and he sadly replied that the Spanish Amal company didn’t make the 50mm he wanted. Swoooon…. I nearly bought a 250 Stiletto MX when living in Australia, but balked when I heard spares were very hard to get. Swede Hakan Carlqvist loved the Ossa he rode in the mid-70’s, but said the same thing – and he was sponsored by the Swedish importer! He tried to buy standard spares from the factory when down in Spain but the various stringent laws didn’t allow him to do so and the factory needed the parts to make complete bikes they could export! He advised me not to buy the latest ’75 model MX’er I was interested in. The Ossa was possibly the best Spanish MX’er of it’s day, only surpassed by the Hakan Andersson Montesa, which of course had longer suspension. Strangely, we could get spares for them.

  • Mito

    Sven,
    the 250 Stiletto MX engine is worth a look at inside .
    Cylinder is huge almost as wide on a twin.
    But it has many more ports over the Enduro, Pioneer and Wildfire type cylinders.

    It is a very nice engine !

    I ran a 350 Super Pioneer in Australia on the road in the 1980’s with a 250 Stiletto engine and chamber , it was a nice bike.
    Quite fast and we went for rides , other guys on BMW and Guzzi and i don’t remember it being left behind.

    Mito

  • Big Sven

    There was talk of an MX rotary-valve Ossa, dropped because it was too expensive. CAN-AM Rotax did one that was great, but didn’t sell in Sweden, or Europe I think, as the Jeff Smith cycle-parts were crap and with all that power the bikes were regarded as death-wishes to ride. But I’ve seen inside a ‘Canny’ engine and was mightily impressed, and the powerband wasn’t ‘the atomic-bomb’ it was made out to be in the press, but about the same as a Maico or the ’76 HVA I raced (with the optional Ohlins ‘spanny’ mounted) but pulling from a 1,000rpm lower and with a couple of more horses on top.

    I’ve just found a couple of piccies that preport to be the Ossa MX rotary development engine, and see it was very bulky, based on the existing MX engine they needed to completely redesign the gearbox area in order to pull the right-mounted carb back a la CAN-AM and slim-off the engine. Obviously money was the problem.

    I did once suggest to HVA that they invite Giro to help develop the new HVA Mag-series engines (they were courting all sorts of design consultant guru’s at the time, I once met Gordon Blair, for ex) but they never did as far as I know. They did pretty-well by themselves!

    There is another aspect to mull over here, politics. There was always ‘friendly’ rivalry between Bultaco and Montesa (an offshoot of Bultaco) but OSSA seemed to be outside even this cartel. OSSA’s success probably didn’t go down well in certain circles, and Giro found himself being sat-on.

    #

    Today’s thought:
    Oh, to turn time back and do it all again!
    (Knowing what you know now, in hindsight).

  • Mito

    I remember the Phantom MX , lovely to ride ,if slightly nervous handling , meaning it was like a race bike.
    Motor was a dream.

    Mito

  • Lloyd Bishop

    The street displacement was 230cc – I don’t know if this factory racer was a 250 – maybe.

    Also – The HP was 50 NOT 30. My stock 250 Bultaco Metralla put out 27.5 CV.