Norman Hossack Engineers a Trellis Front Suspension on a Trellis Frame Ducati 800

Hossack Ducati 800

Hossack Ducati 800 with trellis uprights to complete the trellis frame

Norman Hossack decided to show us what a trellis frame Ducati could look like by engineering a front suspension with trellis uprights. You get all of the performance advantages of a hossack suspension plus lighter weight. One glance at the finished product and the visual symmetry of the combination makes you wonder why Ducati didn't build it like this to begin with.

Hossack trellis uprights for the Ducati front suspension

Hossack trellis uprights for the Ducati front suspension

If you remember Norman's earlier projects shown here on The Kneeslider, like the front drive system he designed specifically for a Hossack front suspension and his "out of the box" square piston two stroke engine, you won't be surprised to learn he's been busy building even more working examples of his design ideas. He's just not the kind of guy to sit around doing nothing.

Hossack wishbones for the Ducati 800

Hossack wishbones for the Ducati 800

Norman has always liked Ducatis and used to race one back in the 60s, so, starting with a Ducati 800 he began looking at the trellis frame to see what would need to be done to adapt a Hossack suspension in place of the telescopic forks. It turned out, quite a bit of work was necessary and most everything in the front half of the frame was rebuilt. Interestingly enough, the frame modifications alone saved eight pounds.

Closeup of the Hossack front suspension for the Ducati 800

Closeup of the Hossack front suspension for the Ducati 800

Then came the uprights and wishbones to replace the forks.

The upright and wishbones are both made from one inch diameter 4130 tube and everything is TIG welded. The upright complete with axle came in at 7 lbs although it could be lighter with thinner wall tubing but as this was a first off 7 would do. CAD analysis shows that a further 1.5 lbs can be removed from the upright with ease. The axle and upright at that weight will quite significantly beat the Ducati in unsprung weight numbers too.

Upper wishbone mounting points

Upper wishbone mounting points

A single Ikon shock handles damping, steering lock has been increased from 26 to 30 degrees and Norm set the handlebars 1.5 inches higher than stock, just Norm's preferences since he rides the bike to work every day. Overall weight loss is about 30 pounds.

Very nice work, Norman! I like it a lot, but I wonder what the Ducati purists will say.

Link: Hossack Design

Norman Hossack and the Ducati 800

Norman Hossack and the Ducati 800

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Comments

  1. says

    Weight loss is great, but has the front-to-rear bias and mass center been optimized with this new setup too?

    I like FFEs so the above is not to be read with a doubting tone.

    Would like to see it painted black with a black frame & lowered fairing.

  2. Bicho says

    Why?…….Why dont all (on road) bikes have the Hossack system!?…it is less flexy,”simpler”,lighter,stiction free, and works better(you can tune the wheel path)+shorter wheelbase!!! GENIUS

  3. menormeh says

    Basically this is a new adaptation of the old girder style front ends which worked quite well in their day. The big difference is that Hossack is using the wishbones the replace the steering head and induce the forces into the frame further back to eliminate the need for the heavy steering head normally in place. Very clever design. The real beauty here is the fact that by simply changing out the shock you could easily change the riding characteristics and it also eliminates the need for front end maintenance like bushing and oil changes. Kudos to you Mr. Hossacj. Now, can you get a manufacturer to use it?

    • Ola says

      Well, BMW already does on the K1300, albeit in cast aluminium instead of steel trellis.

      As for the comparison to a girder fork, they might look similar but the principle of a girder fork is closer to telescopic fork than the Hossack.

    • Robert says

      The Hossack is NOT a girder fork though the two appear similar. The girder fork is vastly inferior since the steering axis does not travel with the suspension. Because of this, the girder suspension is subject to crazy geometry changes and dangerous handling problems. A girder looks cool but is total **** (pick a word) and should not be considered acceptable work from a designer.
      With the Hossack fork, which BMW adopted (duolever) without much if any attribution, the steering axis travels with the suspension. With this the steering geometry can remain useful and safe throughout the range of compression and extension. Steering inputs are often handled via a collapsing link similar to what would be found in an aircraft steerable nosewheel. Something like this is probably beneath the fairing and between the handlebars and the top of the forks.
      If it is not clear the difference in where the steering axis is and how it is very different than a girder, keep looking. It is very similar to a modern double wishbone front suspension on a car which is turned 90 degrees. On a car like this, if the steering axis did not travel with the suspension it would be the subject of ridicule; even from idiots.

      • says

        To be fair, you can get good suspension performance out of a Girder fork if the geometry is carefully planned. At minimum, the axle path and steering axis need to be roughly parallel. Achieving this without nasty brake dive requires either a more vertical steering axis, or (i think) finding space for a trailing link suspension. (or just use a Hossack suspension)

  4. Jack says

    This is super cool. Where is the collapsible scissor steering arms? Or is this not a duo lever like his other FFE ?

  5. says

    While not explicitly shown, there are mounting bosses on the front fork for a scissors steering link like found on Hossack’s earlier bikes. Looks like this link surrounds the upper section of the shock and is almost completely covered by the front fairing.

    • says

      A perplexing picture is the end of the wishbone arms, they are “vertical”, which doesn’t seem to leave much room for much of a turning radius. So, is there a part that is connected to that which pivots on the horizontal plane connected to the bottom of the shock?

  6. Jason says

    I like funny front ends. My only question is why a Ducati 800 instead of a Monster or something else from the current lineup? I suspect the reason is because 800′s are cheap. I would love to be able to buy one as a kit but I doubt there is much of a market for a bike 5 years out of production.

    • Light is Good says

      Norman Hossack unfortunately is restricted to a tight budget. If the world was fair or if he was a more crafty businessman, he would have much better finances. He doesn’t earn a cent in royalties from BMW for the Duolever because they waited until his patents ran out. They didn’t hire him as a consultant either, which would have saved them a lot of time and money as well as allowed him the freedom to experiment the way he so badly wanted. He went bankrupt from financing his own project development and trying to run a racebike to showcase the technology. He built a prototype for the British Ministry of Defence but didn’t get a contract. He is a genius inventor sadly lacking in economic savvy. What he needs is a rich patron who can finance him and get in return fantastic motorcycles and inventions which may be marketable. The motorcycle industry is very slow to change and very risk-averse, so this is why none of the major players have hired Norman or bought any of his patents. Maybe Elon Musk should step up?

      • Jason says

        I know Hossack has had a rough time financially and that is why I speculated that the choice of motorcycle came down to availability and cost. It really depends on the purpose of this bike. If it is just a personal bike for Hossack to ride and tinker with, the choice of bike doesn’t matter. However, if the bike was built as a prototype for some type of commercial venture I think he would have been wise to pay a bit more and use a current model.

        • Scotduke says

          I didn’t realise BMW had waited until his patent ran out. But this is a really interesting piece of design work. I wonder if it steers better than the BMW system? I’ve never ridden a duloever BMW myself but I’ve read the system is ok for touring but not suited to a sports bikes. this design does deal with the shortcomings of a conventional system that requires a massively engineered headstock. It also separates suspension movement from steering. I wouldn’t mind having a ride of that. I wonder if Ducati would try this system out on one of the sports tourers?

          • Jason says

            I have ridden a duolever bikes and own a telelever bike. I went from a Kawasaki ZX-7rr to a BMW R1150R. The telelever works just as well for sport riding as it does for touring. The biggest complaint I hear in reviews is “lack of feel”. I think this comes down to reduced front end dive under braking. The degree of front end dive on bike with conventional forks gives the rider a good indication as to how hard they are braking as they enter a corner. At first it felt weird to brake into a corner and not have the front dive but I quickly adapted. Now it feels weird when I ride a conventional bike.

          • Dai says

            The system is more than suited to racing. There have been 500 singles (Vernon Glashier & John Britten) Vernon used Norm’s bike to race John used the idea for his bike. I know the Britten is a vee twin but th efront end ia basically a Hossack front end.

  7. Don says

    Considering the problems that Ducati Corse are having with their MotoGP machine, I’ve always wondered why they couldn’t have just hired Norman to rig up his FFE on their bike and have a go, rather than spending these last 2-1/2 years in the ‘wilderness’ with a top shelf Ohlins fork that still can’t get the bike to turn!

  8. Christoph says

    Beautiful work Mr. Hossack! I like your design so much more than BMW’s copies of your work. You obviously wanted to retain the airy spirit of the Ducati frame and I, for one, dig the white frame. Being a fan of the early 90′s Ducks I’d like to see your work on a 900ss. I hope you can achieve your deserved success with a frame kit that can be tailored to converting people’s bikes into handling nirvana. I’ve got an early 90′s Suzuki Bandit 400 with a trellis style frame…. please, oh, please….

  9. Tmnstr says

    How apropos! I’ve been researching Hossack’s FFE design heavily over the past week, hoping to find a version on a 2V Ducati. And here it is! I was also curious about the steering linkage and shock placement on this version, as Norman used articulated wishbones in the past. But, this simplified version using the shock as the steering linkage is a much tighter package (and probably more efficient too). I am still curious about the geometry kinematics as per trail changes (if any).

    Norman? Care to articulate [sic] a bit more?

    Cheers,

    Tmnstr

  10. Jamon says

    Shouldn’t the wishbones be equal length (or very close)? This looks like the same problem as the Yamaha GTS1000. The top wishbone was shortened from the original design, so the rake and trail changes as the suspension compresses.

    • todd says

      maybe it’s counteracting the affects of the swing arm as it changes wheelbase under compression. From what I understand, it is desirable to steepen the rake and shorten trail while turning for better response.

      -todd

        • Jamon says

          Just doing some cocktail napkin engineering, it seems as if the rake would increase but the trail would decrease. So do they cancel each other out? A few links seem to say that the shorter top wishbone design retains a constant wheel base, but I’m not sure how that would be more important than the geometry.

          • BoxerFanatic says

            I would think one would have to evaluate the bike as a system, not just the front end.

            Braking shifts weight forward as inertia tries to keep the bike and rider moving.

            It either will try to compress the front suspension with the additional weight transfer, or push the bike up and over, with the front axle and front contact patch as pivot points, depending on how strongly the brake is applied, or locked.

            Both of those effects would tend to try to stand the forks or upright in a more vertical position (hossack-type can tune some of that out), so there is a natural reaction to reduce rake.

            A bit of rake increase dialed into the control arm ratios counteracts that, and tries to keep the rake constant as the bike moves dynamically.

            Also, as the the front either compresses or tries to stand up on the front tire, the rear swingarm droops, before the rear tire comes off the ground entirely, if it gets to a point.

            As the rear swingarm droops, the rear tire swings in a downward and forward arc, trying to reduce wheelbase. A net-zero change in front rake would still reduce wheelbase at the rear tire. A net increase in front rake counteracts the forward movement of the rear tire on the rear swingarm’s arc, to keep the wheelbase near constant… the frame, engine and rider change position relative to the tire contact patches.

            At least that is my napkin-scribbling, non-engineer, figuring suggests.

  11. BoxerFanatic says

    THIS. I want this. I have been waiting for news on this bike since reading that Norman Hossack was going to do one on the Ducati message board.

    Perhaps with slightly more vintage 90′s era 900SS-CR bodywork, a 900/1000cc rev-happy version of the updated 1100EVO fuel-injected engine, and a Monster S4R tubular single sided rear arm… some three-spoke 916-style Brembo wheels… Maybe a Sport 1000 seat and pillion cover, or some other slick but monoposto-type seat unit… and a killer moderate to modest loudness exhaust system.

    I think that is my ideal Ducati.

    • todd says

      nice but the headlight and gauges are mounted on the forks. I can’t imagine how long the bulb would (not) last like that.

      -todd

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