This bike has been a side project in my life for a long time. It was never about having a bike at the end of it, so much as enjoying the designing and building along the way.
My first love was my bicycle, three wheeled at first and then two.
I am no doubt not alone in this romantic memory (at least the two wheeled part), but the sense of freedom that bikes offer has never left me, and as a professional designer of cars, it was only natural that I sketched motorbikes on the side. I moved from England to California in 2000, and seeing the motorbike culture that is alive and well in Los Angeles where I live today, I began to appreciate the history of bike building and modifying that goes on all over the place here. Combining my passion for metal fabrication, it was soon after that I started laying out the design for a motorbike..
I was particularly inspired by some of the images I saw at an exhibition on California (Milk and Honey), that focused on the early years of the 20th century. A time where California needed to be sold to the populous back east in order to lure them out to a hot dry part of the country. Growing up in England, I was aware of the Brooklands circuit, where concrete banking still remains today, but I had never seen anything even in pictures, like the near 50 degree banking of the American Board tracks built in the same period in Los Angeles.
Visually speaking, the beautiful bikes of that era were closely related to their bicycle roots but were legitimate 100mph machines, and the riders of the day were very brave to say the least, not just because of the sketchy nature of the bikes mechanics, but also due to the unforgiving surface that they raced on. With next to useless safety gear, fatal crashes, fifty thousand spectators and horrific splinters remain in my mind from reading about that era of motorsport.
But the way the riders were stretched out on the bikes is what also really captured my imagination, giving a real dynamism to those elemental machines. For me, the tall skinny wheels and tyres balanced nicely with the pure open lines of the frame and engine. In an effort to reduce speeds of the bikes in the 1920's, the organisers halved the engine size from 1000cc to 500cc and we effectively saw the rear cylinder disappear from the bikes, dubbed 'pea shooters', with less meat in the sandwich, these bikes looked even more attractive to my eye.
Smaller riders often improve the appearance of a motorcycle. Their scale alone helps to pump up the proportion of the bike/rider balance, which usually ends up flattering the bike side of the equation. Even taller riders looked good stretched out on board track bikes and that was something I wanted to attain. I had been following the AMD world championships for a few years and often felt a bit less convinced of a bikes otherwise flawless appearance, when I saw the final shot of the winning machine next to its builder. The often diminutive scale of the bike now realised, made me want to focus on the relative scale of my design, and that is what really drove the use of 26" tyres, that at that time had just been made by Vee Rubber for some very one off custom bikes by famous builders.
The other bikes I couldn't get enough of were the experimental european racers from the second half of the century. The range of construction techniques and suspension design was really broad and before the telescopic fork took over there were lots of interesting proportions thanks to unique front ends. One in particular was developed by Norman Hossack. Essentially a double wishbone layout inspired by sports car suspension, this layout had a number of benefits over the similar looking girder fork that dominated the previous decades. Looking at many inventive race bikes through the 70’s and 80’s, these bikes always looked more interesting to me with the bodywork off. The intricate nature of their frame and forks had a technical aesthetic that I really appreciated.
Nowadays, most bike builds use a conventional telescopic fork, which while understandable always frustrated me a little for a number of reasons.
Firstly, literally every bike out on the road and track has that type of fork, so as a designer, you were giving up the opportunity of a unique front end. Some people have done interesting fork guards in an effort to address this issue, but I was still looking for an alternative.
Secondly, because they are off the shelf items, the aesthetics of a telescopic fork are almost never visually consistent with the rest of the bikes design language.
The use of a Hossack layout gave me the opportunity to fabricate the fork legs in a consistent manner to the rear swing arm and give the bike a more coherent and balanced appearance.
A Honda XL500 engine had the air cooled cleanliness and overall layout that I wanted. As well as being a four valve head with parallel twin exhaust ports, the late 70’s early 80’s era engine also had fairly pretty engine cases and covers when compared to the later XL650, which attractively had an electric start as well as more power. However, I braved the kick start and 33hp in favour of the look of the engine, as well as only then needing to package a tiny 6V battery.
I found a local XL500 for sale with a spare engine, which was nice. With that engine three dimensionally scanned, I was able to bring data into my computer and start to see the layout and proportion of the bike. I had the tire size and I also knew I wanted to have a riding position where I (6 feet tall) would fit the bike slightly stretched out with the seat nestled nicely in front of the rear wheel.
Much as I was looking at board track bikes, there were aspects of their proportion that I wanted to avoid, namely the way the suspension sat up high at the front of the bike and the tank fell away stepping down onto the frame, giving the bike a nose high feel. I actually wanted a subtly raked feel to the profile. In order to gain a sense of forward motion on what was always going to be a fairly level and balanced bike with the same size tires on both ends, I ended up raising the centre line of the tank slightly, to avoid the front suspension becoming the tallest point on the profile. It was in pursuit of this dynamic that I packaged the steering in between the suspension arms, suspended on a combination of radial and thrust needle roller bearings, the bars drop out and down further helping to bring the visual weight of the bike down.
From the handlebars, the section of the tanks and their wide point clocks with the seat and creates a raked line through the bike.
With the tire size being a given, I began with the layout of the front suspension geometry and trail creating a steeper than normal steering angle, thanks to the higher axle, thanks to the larger diameter tyres. This and the need to spread the suspension arms sufficiently above the wheel, created my front suspension package. Proportion is clearly objective on any bike, but I felt it critical here using such a tall tyre. I began creating negative space in the bike to balance the volume around each of the wheels.
Before I began fabricating anything on this bike, I had to be sure I could actually make the wheels work. In 2007, although the tires were available, wheels weren't. Or at least not to me. Some builders had made some from billet, but that route was out of the question and forgings were not available either. I felt at that time the only way I would have this proportion was if I could fabricate the wheels in a modular fashion, with the rim being the greatest challenge. I had some 21" rolled steel rims and sensing what big heavy hoops these would be at 26" diameter, I started making a carbon fibre rim from pre-preg unidirectional carbon fibre. I replicated the rolled steel rim in section, just in case I needed to revert back to the steel route.
After making a split mold and layup jig to wind the carbon fibre and roving, it actually turned out relatively well and was very light, I just really struggled to machine the tyre seat of the rim, and after admitting defeat, returned to the steel route and set about rolling out some 21" rims to become 26". A big hydraulic press and some matched tools that once compressed evenly around the rim opened up each 21" rim to the correct radius, to then be cut and re-welded to form one 26" rim.
Once I had a sense that the rim would work, I felt more confident in the rest of the wheels construction which would be a CNC machined hub with unidirectional carbon fibre spokes, with everything glued and screwed together. I had an obsession with large hollow axle bolts for some reason, and machining these by hand was a project in itself. I found the largest wheel bearings I could fit inside the brake rotor spider and made them the basis for everything around the hub, matching the profiles of the rotors and sprocket carrier to the hub.
As I was building the bike in data first, I had the opportunity to use different fabrication techniques. In complex areas like the dropouts and the neck area of the frame (though this bike doesn't have a conventional neck), I wanted to try and use investment cast parts like a lot of lugged bicycle frames do. I was able to print positive parts to then take silicone moulds from. These then in turn allowed me to pour the investment wax pieces. All of the frame tubing is made from 4130 chromoly, and it was possible to have the cast parts made in the same material. This was also the approach for the front wishbones that would hold the fork legs, these were cast in aluminium, for lightness and the ease of final machining for press in deep groove ball bearings.
With all of the cast parts on the way, I drew up a fixture jig for the frame, fork and swing arm, all made from 3/4 MDF torsion boxes with aluminium posts to hold the parts at the correct height. These would locate all of the key components, leaving me to join them together with traditional fabrication.
With the basic frame mounted to the stressed engine. I developed the mounting pieces (yellow part above) to hold the rear swing arm needle roller bearings on the back of the engine/gearbox. The swing arm also has a large hollow axle bolt, like the wheels.
The seat was the one part on the bike I roughed in by hand in clay. This gave me the chance to test it out for shape and comfort, and also to capture some blend of the traditional board track seat and my old Kashimax Aero BMX seat. Once I had this modelled, I scanned it along with the frame, so that I could start to model the seat in data, along with the tanks to match the fabricated frame. The seat made in carbon fibre/kevlar and is cantilevered off the back of the main frame in an effort to create some extra comfort. The tyre profiles are very low and the air shocks quite basic, so this really helps in terms of ride quality. The carbon fibre/fibreglass mud guards are unique front to rear but made from the same tools.
I grew up in my Dads workshop learning to make exhausts, so I wanted to do a good job on this part. In particular, trying to perfect the welds around the tubes and in making the silencers. I made a welding fixture to hold parts and rotate them so I could do my best to impersonate robotic welds.
Fuel Tanks are a split design. They are constructed in carbon fiber and fibreglass composite with brass fittings. Each tank is made of two separate layups and goes together in a shoe box construction. The inner panel (lid) of each tank is hollowed out to create a volume in between the tanks to package the front shock absorber, small 6V battery, regulator, rectifier and the main electrical loom.
The colour scheme of the bike was intentionally dark. I wanted to show the carbon fibre but not in an overt manner, so the contrast to the surrounding black is relatively subtle. The gold/orange colour of the anodising drove the tone of the paint accent colour.
There is not much in the way of decoration on the bike but I could not resist some nice badges on the tanks. Using brass, the idea was to echo something like an enamel badge but using epoxy resin. Then automotive clear over the top.
I have received a lot of help from a few and a little help from a lot of people. You all know who you are, but sincerely I thank you.
Sweet Baby James