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Norman Hossack Builds a Mountain Bike Suspension

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Hossack mountain bike suspension
Hossack mountain bike suspension, same idea on pedal power

What do you do when you’re Norman Hossack and the guys at work start talking about mountain bikes? Well, you might start out saying you could build a better suspension than what the bikes come with, but then your buddies say “prove it,” and you find yourself with some work to do.

Norm laid out four targets:

  • 100mm Wheel travel.
  • Same weight
  • Less flex (mountain bike forks are prone to flex at full extension)
  • Make it fit a standard frame

He came pretty close, but fitting it to a standard frame meant some frame modifications he would usually do were ruled out.

Does it work? Norm says it still needs development, but it’s a pretty interesting design. Personally, I’d like to see the full treatment, frame mods and all, but it’s neat to see what he did within the design parameters he had to work with.

Link: Hossack Design
Related: Hossack Ducati

Posted on Filed Under: Motorcycle Builders

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Comments

  2. ProFlex tried girder forks on their mountain bikes back in the early 1990’s. They were beautifully made and . . . are now obsolete. Don’t get me wrong — I love experimentation to solve problems. But telescopic forks rule because they work well with minimal maintenance.

    • their suspension was made by Girvin which then ran into patent troubles IIRC. I still have my Pro-Flex with Girvin suspension bike…heavy as a tank and not doing much as an archaic relic.

    • I still have my Pro-Flex. I replaced the polymer front suspension with the Girvin shock of the same design. It is still a fun bike.

  3. I think the “no frame modification” rule needs to be there for it to be a viable product. This is a market with everything sold as components, and most things fit in a pseudo-standard. You stay within that standard, and you will sell more parts.

    I also think mini-shock design has progressed a long way since the 1990s, and that mountain bike suspension is more common then it was. So this may sell.

    I think the largest detractor from it is the same as motorcycles. It looks odd.
    The second detractor is it looks heavy… even if it is not any heavier then a fork.

    However, if it works much better.. He may have something he can sell here.

    • Component sales are definitely the way to go, though it would be neat to see the frame mod route, too, if only for comparison.

      If this works as well or better than what’s popular now, some guys would probably buy it just to be different. I think it has potential.

    • the biggest detractor is that they **don’t** dive under a braking load…..when i go ride somewhere like Fernie BC or Moab UT, or Oak Mountain AL I WANT my head angle to be dynamic, to get steeper under heavy braking deep into a turn, and conventional forks do that. Anybody who knows the difference between a ‘recreational’ MTB (think $300-$1500), and a ‘performance’ MTB (think upwards of $2000) also knows that most all modern forks with either a 15mm or 20mm thru axle and a tapered steerer do not suffer from a lack of rigidity…

      • Just wanted to add, for the record my fork of choice is a 5lb+ coil sprung fox 36. It does exactly what I expect it to when I want it to, and if i were worried about the weight, I would just go take a dump before riding….

        • But you haven’t ridden anything with a Hossack front end, have you? So what is your opinion worth, exactly?

  4. I’m curious to see the long-term maintenance of this fork. Horst Leitner of Amp Research did a somewhat similar design with the shock inside the steer tube. The “knuckles” of that fork, just as what I see on this fork, would experience wear quite quickly and make the fork quite sloppy.

  5. Ted, I’m one of the “guys at work” here with Norm, and also a prior bicycle mechanic at two different shops back in my school days. I’ve ridden and worked on both the AMP research and Girvin forks, and they are different from Norman’s at a few key points. The issue with the AMP research design was that Horst’s pivots were all below the steerer tube, in the crown area. Not a problem in itself, but that meant that they were closely spaced. This in turn created a large leverage ratio with the fork legs and thus the pivots were undersized for the forces on them leading to premature wear and a noticeable flex when riding. Girvin solved this the same way Norman did, by putting the upper pivots above the steerer tube. Girvin’s design I would say is much closer to what Norm has done, but Norman’s pivots are far more robust. Due to the triangulation of the swingarm mount points, the design doesn’t rely on the pivots for any rotational alignment, so Norman is literally using a rod end swivel over a shoulder bolt. The load rating on those rod ends is ridiculous. Wear due to contamination over time might still be a concern, but so it is also with tellies. Having had the opportunity to race the bike, I’ll say that the fork performs wonderfully; better than the Manitou Black or Marzocchii Z3 I’m used to in several aspects, and is lighter than either (not that those are light forks, mind you). There was at least one instance where I was forced into a rocky gully on a doubletrack descent, and I’m positive I would not have made it through if it weren’t for the extremely precise tracking the fork offers. Hopefully that trend continues as the fork ages, but I’ll have to talk Norman into letting my ride it some more to get you an answer. I’m working on it! 🙂

    • Indians had a trailing link, leaf-sprung fork – which was garbage. Girders (Druid or Webb forks) were around before Indian decided to use them on some models.

      Though, unlike Hossack’s other designs, this one is a Girder as it has a load bearing steering head. Albeit his is much better because it uses triangulated pivot points instead of the sloppy parallelogram linkage that is used on the traditional girder.

      -todd

      • Sure doesn’t look like a trailing link design,didn’t think I had to say late model Indian front end.

  7. I prototyped a handle-bar drive mechanism on a stock mountain bike that taps arm power and transmits it to the rear wheel thru the left crank arm. It’s got good tractability and a natural cadence (hand grip rises when the pedal falls…like swinging your arms when running). It can be instantly engaged or disengaged on-the-fly by activating a lever with either thumb. I’ve been riding it for over 15 years with minimal servicing. I approached the market about a minute after the mainstream fad ran its course, when the industry had adopted a risk-adverse mentality to weather the down-turn. Now it seems that a new arm assist concept is emerging every other month, so maybe I should hit it again?

    I remember the AMP forks and I’ve wondered why a good alternate to the tellies hasn’t come mainstream. Maybe Norm has something with his set-up. I agree with Paul, though. It’s gotta follow standard protocol. Its gotta be a drop-in component.

    Good luck!!!

    • Long time ago – 20 years maybe – I worked on a two wheel drive/arm+ leg system that was banned by the UCI before we could even finish testing it… Was with Mr Cloarec of Nice.

    • When some of you fine folks say “tellies”, I’m pretty sure you mean telescopic forks. Although, there’s this nagging suspicion that one or two of you could mean tele-lever forks?

  8. I love it. I agree that bikes are completely a component driven business. If it were produced as a component, there’d likely be a market.

  9. It appears that the rake/trail would suffer (change) under flex… same issue amp research had..

    • they were very lightly built XC specific forks and people pounded them on DH: then complained when they werent up to it.

      I actually have a set of NOS B4’s hanging on the wall of my garage never mounted because they are so cool.

    • I never rode the AMP stuff, but as a long-time rider of a Girvin Vector, there were two principle problems with the design and I think this effort only fixes one of them.

      The terminal one is that the fork could easily be twisted out of alignment; that’s what eventually killed mine, when an angular load ended up bending several of the linkage components. This was of course fixable by replacing the elements, but the cost was similar to replacing the whole fork with a more traditional unit.

      From what I can see of this fork, it’s not clear that it is going to be a lot stronger than the Vector, but I’m willing to give them the benefit of the doubt.

      As the post I’m replying to mentions, however, the rake and trail of the Vector were quite variable, and this fork looks like it would have exactly the same problem. Not, variability is not in and of itself critical, but with the Vector it certainly was.

      In level riding the path (which followed a J pattern) was actually pretty beneficial, allowing the fork to “give” a little as it hit an oncoming obstacle before going up and over. But in a downhill facing situation it was horrible: The fork is under high load when breaking, compressing it, and significantly reducing rake and trail as a result. That caused huge instability problems, resulting in many crashes.

      The biggest win with that fork design, precision, is no longer so dramatic with today’s 15 and 20mm through-axle forks – which are easily stiff enough for the job. But wheel flop is not really a problem with the current traditional axle forks, so you’re really solving a problem that doesn’t exist.

      Add to that that bushing contamination can’t help but be a problem (although it wouldn’t be hard at all to do a better job of this than Girvin did, theirs were seemingly made of soft cheese and a constant maintenance headache), and the fact that it’s quite difficult to make a girder fork lighter than a traditional fork, especially one that is air sprung, and you get something that solves a problem we don’t really have anymore, is heavier, is more expensive, and is less reliable.

      In short, I won’t be ditching my Manitou Seven MRD any time soon….

      • I apologize for the spelling mistakes (I can’t believe I used “breaking” when I meant “braking” :-/ ). Typing and editing on an iPad is … lousy.

        • I dun no, jim…I could see the Hosack fork coming in well under tellies once the usual weight reduction methods are applied. As for function, the design has inherent tuneability…but we’ve been told (by someone who’s actually ridden it hard) that it already works very well.

  12. Looks great for a girder.

    But the “no frame mods” kills Hossack’s ingenuity, and the big difference between this girder front end, and Norman’s innovative motorycle suspension.

    Not steered control arms… solely a steered upright, and the control arms mounted to the frame. SLA. Double-wishbone… whatever you want to call it.

    They should have let Norman Hossack have purview over the frame.

    Still. if it is a girder, but doesn’t add weight over the original (likely telescopic) forks… that isn’t exactly bad… and the steering axis isn’t offset by as much as a Girder front end would usually be… so not bad.

    Still looking forward to Hossack’s plans for a Ducati SS, and I still want a K1200R-Sport with Hossack Duolever.

  13. Love this concept of Normans. The link arms look to be unequal length and at different angles, so I’d have to guess Norman is designing in a better wheel path than the simple linear compression of a telescopic fork. I think he has something potentially really game changing here.

    I would love to eliminate all of the fragile surfaces in a telescopic fork, several thou wear on Kashima coating and your stanchions are shot and your fork is pooched. This looks simple, robust and serviceable, and might have a wheel path that compliments current rear suspension.

    Carbon fiber might be a good application for the girder to keep weight down. I wonder if this system could get below the 3 pound barrier and still give full suspension functionality?

  14. Another neat piece of design engineering from Hossack. I hope he can finish development and get it into production. I know a lot of mountain bikers are looking for an alternative to conventional suspension forks, which have their limitations. This looks simple and rugged

  15. I wonder if he’ll develop this further…

    Norman Hossack did a motorcycle concept for the military that had a single-sided front upright, and it was sealed and valved to hold pressurized air in reserve.

    One could dismount the front wheel like a car, or single-sided rear swing arm, and change the tire, repair the tube, or whatever, and then re-inflate the repaired tire with pressurized air stored within the volume of the front suspension upright.

    It would probably a one-time deal, and then you’d have to find a base (or in civilian trim, a service station) to re-pressurize the reservoir again… but repairing the tire and re-inflating it once might well get you to that next stop.

    I wonder if an air-pressure reservoir design would help on a bike for field repairs. Quick release hubs are simple enough on bicycles, so probably don’t require a single-sided wheel attachment method, though.

  16. They could potentially do a full frame and suspension design together. That may allow them to optimize the performance. Foes has a couple bikes that use their own suspension components and so does Maverick.
    This may actually work well, helping to eliminate brake dive could be good on a bike that is facing downhill already. I know it hasn’t worked for sport bikes, but this may be a good application.

    • I love the idea of trailing link forks. With a single pivoting point, they give a much better wheel path than single pivot leading link designs. They have some inherent disadvantages though, including weight distribution away from the steering axis and a tendency to have prodive geometry. Still, many generations of Vespa and Piaggio owners have been delighted with them.

      I hadn’t heard of the Lauf fork before. I’d have to ride it to see if it works as well as it looks. No pivots vs. Hossacks six pivots. Looks like a short wheel travel, let’s say 20-30mm (about an inch) vs. Hossacks 100mm. They appear to have made everything out of carbon composite, so it’s very light. They appear to have balanced the weight well about the steering axis, with the fork legs in front and the brake caliper mounts or ‘uprights’ behind. The twelve carbon fibre springs are presumable stiff enough in torsion to keep the wheel tracking straight.

      I like Norman’s design, even if he had to make it a girder because he wasn’t allowed to mess with the frame. The triangulated design and offset lower pivots are an improvement over the Noleen design. I hope he manages to market it successfully. He knows his two-wheel geometry so I’m sure it handles well. I just wonder what he makes of Laurie Smith’s design with more upright fork legs to reduce loss of trail?

  18. Since Norm has proven this technology many years ago and it is being used successfully by BMW I think we aught to give him the benefit of the doubt. There may well be some engineering constraints imposed on him who knows. All said and done if this bicycle performs as well as his other bikes then I hope it takes off for Norm he deserves the break, more than paid his dues.

  19. Interesting stuff and I think well worth developing.
    Some thoughts regarding comparisons by Chester who spent time on it. I think if this new arrangement is to be accepted it needs to perform better than what is available.

    Comparing it to (and improving upon) a Manitou Black or Marz Z3 isn’t enough. It would need to be stiffer than a 34mm stanchion top shelf fork with 15mm or 20mm thru axle for starters. Otherwise people won’t seriously consider moving away from the tried/true and mature technology of telescoping forks.

    One potentially significant benefit to this linkage arrangement however, is the possibility of it being fitted with an existing, proven, and accepted “rear” shock of the customers choosing.
    The idea of being able to purchase this linkage fork with required travel, well tuned wheel path and offset for wheel size *and* having it supplied with (or accept) an existing spring/damper package from Cane Creek, Fox, or SRAM would (I think) make it a much less “risky” investment to a potential customer.
    example: the fork isn’t accepted by the market but the owner still has a marketable rear shock to re-use or recoup costs.

    Basically, if you’re going to try to wedge yourself into this market you’ll have to solve real and easily identifiable problems like;
    Weight. I’d suggest max 3.5lbs as there are very competent offerings in 4lb range for 140-160mm forks
    Rigidity. Will need to track at least as well as top shelf offerings with 34mm stanchions and 15/20mm axles.
    Durability/Serviceability. Intervals greater than 60hrs ride time with reasonable overhaul costs.
    Promise of performance based on existing Spring/Damper (rear shock) offerings with tune-able High and low speed compression damping and spring curves.

  20. Can’t really say how this setup would work with all the 29’ers and 27.5’ers that are the bike de jour style right now. This example seems to be of a bygone era, reduced to a quaint argument for alternative design, only to be eclipsed by superior manufacturing and technological advancement….