Forkless Motorcycle Tears Up The Track

The bike above may look like a pristine Yamaha prototype, but it’s actually the work of [Julian Farnam], a motorcycle hacker of the highest level. We caught his Yamaha A-N-D FFE 350 on OddBike, and you can read [Julian’s] own description of the bike on his Slideshare link.

The FFE 350 started life as a Yamaha 1990’s RZ350 two-stroke racer. From there, [Julian] gave it his own Forkless Front End (FFE) treatment. Gone is the front fork, which while common in motorcycle and bicycle design, has some problems. Fore-aft flex is one – two thin tubes will never make for a rigid front end. Changing geometry is another issue. Since forks are angled forward, the front wheel moves up and to the rear as the shocks compress. This changes the motorcycle’s trail, as well.

Forkless designs may not have these issues, but they bring in a set of their own. A forkless design must have linkages and bellcranks which are often the source of slop and vibration. [Julian’s] design uses two sets of linkages in tension. The tension between the two linkages removes most of the slop and provides that directly connected feel riders associate with forks.

The FFE 350 wasn’t just a garage queen either – it laid down some serious laps at local tracks in Southern California. Unfortunately, the forkless design was too radical to catch on as a commercial venture, and the FFE has spent the last few years in storage. [Julian] is hard at work bringing it back to its 1998 glory, as can be seen on his restoration thread over on the Custom Fighters forum.

19 thoughts on “Forkless Motorcycle Tears Up The Track

  1. I could see why he chose an RZ350 for the start of the project. It’s very light to start with, steel frame with plenty of triangulation and the powerplant is TINY, with very little emissions crap surrounding the top end (seriously, the motor and gearbox only weighs 88lbs but can still crank out 50-80Hp with the right mods (do I spy a pair of Toomii traps?)

  2. theres a few standard production bikes with front swingarms..
    hell even some of the most common scooters have them!
    nicely made all the same.
    Also the sxv550 motor is 70lb and can be tweeked to put out 120hp/55lbft. its an increadable piece of work.

      1. Perhaps it’s the somewhat vague statement “Unfortunately, the forkless design was too radical to catch on as a commercial venture” that’s causing confusion. Perhaps too radical for Julian to make into a commercial venture? I’m not sure how much of a commercial venture is in the Bimota Tesi [1992] and the new Tesi 3D either though, it’s very boutique and small run.

        1. Don’t forget the Vyrus, which is a fork of the Bimota Tesi workers. They make a version with Ducati 2 cylinder engine, and IIRC a Honda four cylinder version (used in the CBR 1000RR Fireblade).

  3. Compression of the shock does not per se alter trail. Viewed from the side of the bike, trail is the distance between the points where the fork line (ignoring rake) intersects the ground and the center of the tire contact patch. This distance depends only on fork angle and rake, not length.

    1. i know nothing about bikes, but surely if the forks compress, rotating about a fixed point at the rear, then the angle of he forks relative to the ground (and therfore the centre of the contact patch) does change.

    2. When you compress the forks, rake is necessarily altered (especially upon braking, where the rear shock absorber stretches and the weight moves forward). Unless you compress it by adding weight to the CG of the bike, with both suspensions compressing equally – then you keep the same trail.

    3. There have been lots of leading link forks on bikes: http://motocrossactionmag.com/home-page/the-fork-design-that-almost-mad-eit-big. On dirtbikes, front braking force could be used to force the wheel down and increase braking. Honda had something that would help the back squat.

      On a street bike, racers use something called trail braking. By lightly dragging the front brake, they compress the forks. This makes the geometry change to allow sharper turning. If they do too much, they can tuck the wheel and slide out, so it requires a careful and controlled touch.

      In the 80s, many manufactures had anti-dive tech on their bikes. None of them have it now.

  4. This area should have some attition to Tony Foale, who has to be the #1 driver of HCS in motorcycles. In fact he productionized short runs of hcs equipped rz’s, see later in my post about someone restoring one of his early bikes.

    There are production FFE’s (funny front ends) on bikes, the bimota Tesi (and before you say nobody can afford one, I have rode one, and I have a YB8 in my garage at the moment), the arp racestation vyrus (naked tesi…), the bmw telelever is a amalgamation of the two, yamaha gts1000 (though they screwed the geometry up to make it ride more like a telefork equipped bike) etc.
    I also know of Mark M6NTL who has two ffe’s under development but who’s recovering after smashing his leg to pieces on a dream once in a lifetime ride across route66 (Mark lives in the UK) on a Triumph Tiger that went wrong though I suspect he’ll relish using the Ti they fitted him with to hold the mess together onto his bikes afterwards, one is a revamp of a Foale Q1R
    http://www.oldskoolperformance.com/forum/viewtopic.php?f=6&t=5059

    And One a complete scratchbuild.
    http://www.oldskoolperformance.com/forum/viewtopic.php?f=6&t=64&hilit=hub+steering&start=616

    Another area where HCS makes a massive difference is Sidecar outfits, a standard telescopic fork twists sideways mid corner under sustained sideways pressure, and the geometry is all wrong for a vehicle that doesn’t bank, so the net result with a larger chair and a big bike is to have to fight the handlebars in long corners. The hub centre or leading link conversions eliminate this. Again, actual experience, I rode a kawasaki 750 with a double adult watsonian oxford chair on it for a while and had a spin on some friends non tele equipped bikes.

    I may build one myself one day, but I’ve got about 7 bikes in project form already, cnc machine rebuilds and all sorts to get through first, and Ive just started tinkering with 3d printering with a printrbot simple metal (already being changed!). Need more hours in the day!

    1. I’m a wikipedia expert speaking :-/

      http://en.wikipedia.org/wiki/Hub-center_steering

      “The advantages of using a hub-center steering system instead of a more conventional motorcycle fork are that hub-center steering separates the steering, braking, and suspension functions.” Controlling brake dive dynamics seems like the stand out advantage.

      I thought I read that forkless designs can also reduce tank-slapper risk, but I can’t find a source :-(

    1. This sort of stuff precedes manga.

      Motorcycle makers are surprising conservative, designs don’t change unless there is a real advantage (actual or perceived), and even then rather slowly.

      As mentioned front-ends-that aren’t-forks have been tried and discarded before – forks are simpler, cheaper and work just as well.

      See also drives-that-aren’t-a-chain, that’s a long list too.

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