Forkless Motorcycle Tears up the Track
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.
Oddbike Article:
As far as motorcycle design goes, manufacturers tend to err on the side of conservative engineering. Stick with what is known, what is common, what is produced in great quantity and with known characteristics. This is especially true in suspension design. With the current proliferation of so-called “conventional” telescopic forks, it’s quite easy to forget that there are hundreds of alternative front suspension designs, many of which address the key weaknesses of traditional forks with distinct performance advantages.
One man sought to apply the principles of a forkless front suspension in a bike of his own design. He designed it, refined it, and built it himself. Julian Farnam is the type of builder who inspires accolades and envy – here is a man who, with minimal resources aside from his own talents, built an advanced and beautiful one-off that looks like a priceless factory prototype produced by a massive R&D department. That bike is the FFE 350, a stunning custom bike based around the engine of a Yamaha RZ350 which recently wowed crowds at the One Motorcycle Show in Portland, Oregon. While it has recently been garnering attention on the web among motorcycle geeks, Julian has been tinkering with the FFE and forkless designs since the early 90s.
But first, lets talk about forks. Today’s telescopic dampers were just one of many solutions that were tried out in the early days of motorcycle design. Racing quickly improved the breed and weeded out the ineffective designs, and telescopic forks with hydraulic damping came out the winner by the 1950s. Despite their advantages and decades of intense development, telescopic forks still have significant weaknesses. The most obvious is flex. Having two spindly tubes holding the front wheel out at an angle, with three relatively small clamping points (axle, top and lower triple) means that there is a great deal of lateral movement inherent in conventional forks. Upside-down designs improve rigidity, as do oversized triple clamps and fork braces, but flex can never be entirely engineered out of the design – it needs to be accommodated and compensated for.
In terms of performance, the design of conventional forks is such that bumps are constantly altering the geometry of the front end. As the forks compress, they shorten, and the wheel moves up
andback, which changes the trail of the bike. Braking and acceleration also alters the geometry due the angle of the forks. The horizontal forces exerted by braking compress the fork, the front end dives, the weight pitches forward, and you load up the front tire. Not ideal, but we've grown accustomed to the shortfalls and learned to tune and ride around them.
Conventional forks pivot around a single stem in the headstock, which necessitates a beefy frame with a large spine (or heavy perimeter spars) to brace and channel the considerable forces coming from the front end. The modern frame has evolved around this need – you have a round steering head attached high in the front to a set of tubes or beams which then channel forces into the rest of the frame, or through the engine cases if the motor is a stressed member. With a front swinging arm design, you can practically engineer that bulky frame right out of the equation: you simply need a relatively minimal spar that connects the front and rear suspensions together, ala Bimota Tesi or Yamaha GTS1000 which bolt frame plates to the lower sides of the motor. Steering is through an unstressed linkage that connects the handlebars to the front swingarm. You end up with a simpler and stronger frame, better mass centralization, less weight, and fewer flex points in the chassis.
Several engineers experimented with alternative front suspension designs in the 1980s and 90s, with some manufacturers jumping on the bandwagon. Bimota developed a hub-centre steering setup for the 1990-94 Tesi which would become the prototypical funny-front-end production bike and spawn the subsequent 2D, 3D and Vyrus designs. Yamaha famously adopted James Parker’s RADD swingarm design for their under-rated GTS1000 in 1993. Meanwhile Honda and ELF experimented with single-sided front and rear swingarms in racing during the 1980s and 90s. BMW has perhaps been the most open-minded company when it came to developing an alternative front suspension on a road bike - they have been producing their Telelever (Saxon-Motodd design) front ends since the 1990s and their Duolever (Hossack design) setup since 2004.
Tony Foale is one of the most prolific inventors of alternative suspensions, having built numerous functional prototypes over several decades. Foale experimented with different geometries and swingarm arrangements, finally settling on a design that combined an upright steering arm like a Hossack fork with a swinging arm that resembled the ELF Honda single-sided design acting on a single shock. Foale described his setup as a compromise between the two designs that offered advantages over both. The arms are arranged in a parallelogram with a tube linkage running through a pivot and then connecting to the controls. This basic arrangement would serve as the inspiration for Julian’s FFE design.
Julian has been a lifelong motorcycle enthusiast. He began riding at age 12, when his dad bought an old Rupp minibike from Julian's uncle. After a few years of off-road riding, he got an RD250 on his 16th birthday. So began a life long love of street-going two-strokes. So it is only natural that during his stint studying Transportation Design at the Art Centre College of Design in California he would gravitate towards two-wheeled projects while most of his classmates remained dedicated to the four-wheeled variety. It was here that Julian cut his teeth with motorcycle design and alternative front suspensions. As part of a Yamaha sponsored design class, students were given pre-production Zuma scooters to modify. Some built non-functioning design studies, but Julian took the project a step further - he built a forkless front suspension, designed the scoot like a futuristic off-road machine, and made it a fully functional prototype dubbed the Recon.
The next step was to build a
real bike based on his principles for an alternative front suspension. Something a bit sexier than a scooter. This being 1990, the performance-minded enthusiast had two options - a big, heavy four-stroke or a lightweight, rip snorting two-stroke. Julian chose the latter, not surprising considering his long relationship with two-strokes. He began building his chassis around a liquid-cooled Yamaha RZ350 mill, the king middleweight street 'smoker of the day.
The project began on pen and paper - in those days CAD programs weren't accessible unless you had access to an advanced R&D department with a big budget. Julian worked on the project in his spare time, with a bit of help.
"I was living in a small apartment in San Francisco with no shop or garage, but found a few people who were very generous with their time and resources. One of those people was Derek Capito of MotoLab in Redwood City who let me come and work in his shop in the evenings. That's where fabrication of the bike began. The design office were I was working at the time had a wood-working shop in the basement and I would also work there in the evenings creating the match-boards (patterns) and core-boxes that would be used in creation of the many aluminum casting that would become the various suspension components." What was supposed to be a one year project stretched into two, then three, four... It wouldn't be until 1996, after nearly seven years of work, that the FFE would be ready for primetime.
A custom twin-tube cradle frame was built without a headstock or backbone, with gusseted brackets where the front suspension components would mount. A vestigial headstock is mounted on a separate subframe to carry the controls and instruments. The result looks remarkably "stock" to the point where people mistakenly believe it is a modified RZ frame. The rear swingarm was taken from the FZR400RR with a milled two-piece Kosman rear wheel and a Fox shock. The front suspension would be patterned to resemble the rear - similar construction would be used on the front swingarms, another Fox shock would suspend it, and a replica of the Kosman wheel would be made.
As the FFE uses a single-sided front swingarm, there was the issue of accomodating the brakes. If you have double sided arms you can retain the standard brake discs mounted on either side of the wheel. But on a single-sided arm you are limited to a single disc mounted on a stub axle, like you'd find on a car. Julian wanted top braking performance, so a single disc would not be adequate. His solution was ignenious - fabricate a hub that carried two discs running parallel to each other, with a single oversized caliper shared between them. He built the hub and mounted it with a pair of FZR rotors on full floating buttons, then had a custom automotive style six-piston caliper designed by Performance Machine with a three pad setup. A doubled-sided pad sits between the rotors, with the usual piston driven pads on either side. When the caliper squeezes the outer pads, the floating rotors get clamped together, sandwiching the third pad in between - two rotors, one caliper, with braking power to spare.
Julian cites Foale, Parker and Nico Bakker as his inspirations for the front end design. The overall design is based on Foale's principles, with a large upright steering arm connected to the controls via an A-arm and a series of linkages running through a simple bell crank mounted above the engine, under the gas tank. Where Julian's design differs is in his use of doubled, parallel linkages. At first glance they might seem redundant, but they serve an important purpose. The bane of forkless systems is slack and slop in the various linkages and bearings, which are far more numerous than on a telescopic front end. Any free play is magnified and channeled up to the rider, resulting in sloppy controls and vague steering. Julian's solution was to have parallel linkages with a slight amount of tension in them, acting against each other, to remove the slack from the system. Apparently this relatively simple solution is quite effective, and the FFE has very precise steering for a forkless design.
At first glance you could easily mistake the FFE for a factory prototype*, such is the level of detail and skill put into the project. And this is precisely what Julian was aiming for:
"My design intent in addition to experimenting with some of my own suspension ideas, was to create a motorcycle that looked like a factory made bike. I went to great effort to use the same materials and manufacturing methods on the custom parts as used on the factory made parts. If the rear swingarm was made with sand castings welded to sections of sheet aluminum, then my front swingarm needed to be made the same way. That is also why the current paint scheme looks like something Yamaha would have done. I want this bike to look like a modern RZ350 rather than just another bike customized in someone's garage."
The bodywork retained this OEM look, via a standard RZ tank and a Ducati 916 tail modified to suit the design. The bike was left unfaired, so the clever engineering of the front suspension is on display for all to see. The result weighed around 350lbs, with all the stomping performance you'd expect from an RZ. Julian says that he could probably pare down the weight, especially the unsprung mass on the front end - he overbuilt many of the components to ensure safe operation, but the availability of modern CAD design and computer stress modeling means that he could simultaneously lighten and strengthen his design.
The proof is in the riding, and the FFE performed remarkably well. Julian took the machine to several trackdays and offered it up for testing. It was driven in anger on three occasions, with excellent results at each outing. Julian proudly notes that Tom Dorsey turned in some potential 450 Superbike-winning times at Button Willow, not mentioning the praise the riders gave for the design. Julian described the characteristics of the FFE:
"In a nut shell, it rides very much like a conventional modern bike. Its very stable at high speed, yet will flick into corners very quickly. The road feed back is excellent due to the redundant linkage system which virtually eliminates any free-play in the steering connections. The one noticeable difference is a lack of nose dive under hard breaking. When applying the front brakes, the front will dip a little because of weight transfer, but won't compress radically like a conventional bike might do if you grab a handful of front lever. This is particularly nice in that you can make speed adjustments mid-corner and the bike won't stand up or do anything weird. Its a very fun bike to ride."
Anyone who had ridden a Duolever BMW will be familiar with that lack of front end dive, which can be disconcerting at first but quickly becomes an advantage - you can brake harder and with more confidence than on a telescopically suspended machine.
After finishing the FFE Julian started his own frame company, dubbed A-N-D Vehicles, to offer racing chassis kits for Kawasaki EX500 twins called the AK-1. While the FFE was an impressive piece of engineering and a showstopper, it wasn't a viable design for production. The AK-1 was a more conventional chassis that had broader appeal - it was a trellis frame and swingarm that used the venerable 500cc parallel twin to build a relatively inexpensive but effective racer for
AFM 500cc twins categories. The AK-1 kit allowed the builder to use modern sportbike suspension, wheels and brakes taken off popular bikes, something that would normally require a lot of modification to fit the stock EX (not the mention the fact that the EX frame and swingarm were obsolete designs dating back to the mid-1980s). For $3250 you got a frame and swingarm, while a $4750 kit included a subframe, rear wheel hardware, and various brackets to complete the machine. Quality was apparent, and there were definite shades of Bimota in the brightly painted trellis spars mated to milled alloy rear plates. The AK-1 competed in AMA Pro Thunder and AFM Twins, with some notable victories in AFM - A-N-D framed bikes took 2nd and 3rd in 2001 and won the championship in 2002. Unfortunately the venture didn't succeed, despite the good results and praise from seasoned racers.
Today Julian works for Dolby Laboratories in San Francisco as a mechanical engineer, but he still finds time for two-wheeled contrivances. He recently completed a cosmetic refurbishment of the FFE 350 to put it back on the road after several years of disuse, which included a new paint job as well as the addition of some street equipment so he could ride it on the road. He continues to build custom machines in his spare time, and has crafted some interesting projects. He has participated in the "Dirtbag Challenge" where one must heavily modify a bike within 30 days for under 1000$ (including the cost of the bike). Last year he managed to cobble together a
leading-link chopper RD400 that he exhibited alongside his FFE at the One Motorcycle Show.
Julian Farnam is one of those talented tinkerers who work in relative obscurity, occasionally displaying their brilliance to the outside world but generally operating independently and for their own amusement. I felt compelled to profile the FFE 350 to publicize Julian's creativity and share his story with a wider audience. Julian is a talented builder who does what many of us dream about, and what American hot-rod culture celebrates - successfully reinventing the wheel in our garage, in our spare time, with our own hands and some creative thinking. The FFE 350 is a testament to Julian's forward thinking and the quality of his engineering - it is still striking enough to turn heads 17 years after it debuted.
*I was fooled myself, and incorrectly reported it as a modified Yamaha prototype on the OddBike Facebook page. My initial research led me to Julian's rebuild thread on the CustomFighters forum - my immediate reaction was "how did a streetfighter builder get his hands on a priceless factory prototype?". Upon further investigation I discovered that Julian was in fact the designer, engineer, and builder behind the project. Shortly after I contacted him to get more background on the FFE and his philosophies, which became the genesis of this profile. I want to thank Julian for his input, and give kudos to him for building one of the neatest bikes I've seen in a long while.
