Riding the Foale framed machine back to back with the virtually standard chassis race bike was quite an eye opener. The same day of this test I had also thoroughly enjoyed punting a relatively standard Z1 around the fast and challenging Mallory Park circuit and treated its foibles as simply the way seventies bikes went about their job. Within the hour I was back out on the circuit to sample the delights of the more conventional racer looking Foale framed machine and boy, was I in for a shock, albeit it a pleasant one. Everything the Kawasaki framed machine did wrong or badly, the Foale simply excelled at. Where the sit up and beg bike wallowed and bucked, the head down and bum up approach of the latter machine produced a far more relaxed and rewarding ride.
In all areas the UK designed chassis is light years ahead of the Kawasaki tube work. The engine appears to be slung higher in the Foale than the standard machine and a quick measure with a make shift yardstick reveals it is indeed around and inch or so further up the chassis. This should make for a sluggish top-heavy machine but the reverse is actually true with the bike proving immensely nimble and light as we sped around the busy Mallory park circuit. The steering is devastatingly sharp while the feedback from the chassis is instantaneous and thoroughbred like. This feels like a factory race bike, which if we take into account Tony Foale’s long-standing appraisal in the art of chassis design, in reality it is.
Where the Lawson styled machine needed muscling around the combination of fast sweepers and tight chicanes the Foale bike made light work of the experience just getting on with the job in hand and working with the jockey rather than trying its best to embarrass him. Every part of the UK built chassis works in harmony, if it were a choir then not a bum note would be heard anywhere, from the bow to the stern the bike is rock steady and seemingly without fault. Unlike the spindly sections of framework the huge industrial size 41mm Italian made forks, borrowed from a Ducati, look more than able of handling any front-end task and they are. The precision with which they work keeps the front end firmly planted under all of the tasks that a race bike has to perform and the feedback up through the bars is almost tapped into the very nerve endings. The latest in Pirelli 17-inch radial rubber no doubt helps this process and is testament to the huge strength of the Foale frame being more than capable of holding this amount of modern day grip in check and on course.
While all of these good manners were impressive under acceleration and diving full bore, deep into a fast bend it was never more so than when on the brakes with the big bike stopping straight and true throughout the session. This in turn resulted in some pretty quick lap times as the dead stop for both the hairpin and the new Edwina’s section became great place within to gain time on other bikes. The brakes could be left well into the “Jesus Christ” zone and then carried all the way into the apex point if required although the apparent light weight of the machine meant it had usually hauled up to a workable speed well in advance of that area. As the bike was entering turns more stable when compared to the other machines it could also be turned in more accurately and the chassis wasn’t unloading all of the knots and contortions through the suspension in the process. The ride is exemplary and totally addictive, the 20-minute sessions ending far too soon for my liking, a whole day on track with the Foale Kwak would have been far more preferable.
The chassis with its huge single spine tube was designed by Tony Foale in the mid seventies and luckily was easily adapted to fit around all of the four cylinder Japanese engines of the period. In its original guise the bike would have been clothed in a period Dyson body kit but thankfully the present owner dropped upon the stylish seat and tank unit seen in the pictures while walking around an autojumble. It does look rather nice, and fits in with the Foale chassis design perfectly although no one to date has any clue what it originally came off. Underneath the fibreglass bodywork sits a small fuel tank borrowed from an AR50 Kawasaki that is just large enough to supply the required amount of juice for UK short circuit stuff.
Talking to the daddy
Riding the Foale framed machine left me with a whole note book full of questions and quandaries, luckily the creator Tony Foale is still around and more than willing to answer my queries. Tony is residing in Spain these days and mainly concerned with writing books and giving lectures on his revolutionary frame design and race bike thinking. Having sampled a few of his designs I fully understand the publics interest in this work.
CP; The chassis is built around a single large down tube, how did this radical design come about.
CP; In some old pictured of your designs the front forks look like leading link items, where these common place.
TF; Most had telescopic forks, either the Japanese originals or Ceriani’s depending on each client’s wishes, generally determined by the size of his wallet. The leading link forks were an option but not many were ever fitted.
CP; The engine is a few millimetres or so higher off the ground in your chassis than with a std Kwak and yet the steering is far faster and the bike more manoeuvrable, it doesn’t feel top heavy and is a delight to “chuck” around is there a reason for this as usually a high engine creates another set of problems and contributes to an unstable or lethargic feeling machine.
TF; I have always hated bikes that feel top heavy and ponderous and so it was always a priority for me to try and avoid that. With those Kwaks it wasn’t just one particular feature but more a design philosophy throughout the whole bike. Long before “mass centralization” became the buzzword that it is today, I tried to
keep things as compact and centralized as possible, but that has to be combined with the right steering geometry and frame stiffness. Those bikes were also considerably lighter than their contemporaries.
CP; The bike is so stable under braking tracking straight and
true no matter what I did to it, It certainly aids a fast lap time as the entry to corners if rock steady and accurate, is this a design feature?
TF; It’s all part of what I described in the first answer. Thinking of the bike as a whole unit not a collection of pieces. Frame stiffness was particularly important in this case.
CP; The tubing looks to be far thinner and more lightweight than any Japanese frame from the period and yet the chassis is tight and feels immensely strong, this is noticeable around the fast sweeping Gerrard’s bend that is the real key to a fast lap of Mallory park, the bike is manoeuvrable and yet rock steady over the bumps and scrapes from where so many before us didn’t quite make it. Is the strength in the single main tube or is it from the whole design?
TF; Yes the tube wall thickness was thinner, but that was only possible because of the general structural design and attention to detail. Using thin tubing with the common type of double loop frame would result in excessive flex and increase the chances of cracks and failures. The main tube certainly provides a lot of stiffness but that wasn’t enough on its own because it ended quite some distance above the swing-arm pivot. The connection tubes are quite small but I kept them as straight as possible. From a side view you can see that they are well triangulated to the backbone. The rear pair of tubes is connected to the backbone via a box section, which transfers loads in an efficient manner. There were several other structural details, which were designed to help achieve lightweight together with improved stiffness and low probability of cracking.
CP; Would the same theories you have developed over the years be just as applicable to more modern tackle or are they getting it about right these days?
TF; Several of the features which were poor on the 70s and 80s bikes have been improved. Back then, frames in general were just too flexible and the bikes were certainly way too heavy. Today’s dual beam frames are generally stiff enough but the frames, even in aluminium, are still heavy, although the bikes themselves are sometimes lighter. Ducati have shown in recent times that there are other ways to build frames. As far as theories go, there wasn’t anything special that I did, I always try to find sound engineering solutions to what are the biggest problems with a particular model or type of racing. The only thing that changes with time is the nature of the most urgent problems. The methodology for solving them remains the same. Vastly more powerful engines and grippier tyres have changed priorities and so the solutions need to be considered with that in mind, but always according to the principals of physics.
Check out www.tonyfoale.com for more on Tony’s unique frame thinking
Tony Foale Z1 Kawasaki Specifications
- Engine Gpz 1100 air-cooled inline four DOHC two valves per cylinder, cylinder head gas flowed
- Capacity 1098cc
- Bore & Stroke 72.5mm x 66mm
- Carburetion 4 x Mikuni VM28
- Power – 108bhp@8500rpm
- Torque 55ft-lbs @7500 rpm
- Transmission five-speed wet clutch
- Frame Tony Foale built spine frame, modified to accept GPz1100 engine
- Suspension Front Ducati M1R 41.7mm forks
- Rear DeCarbon single shock
- Brakes Front twin 300mm discs Brembo four piston calipers
- Rear 250mm nissin twin piston caliper
- Wheels Front 120/60 X 17 Pirelli Dragon Supercorsa radial
- Rear 160/60 X 17 Pirelli Dragon Supercorsa radial
Foale Kawasaki Z1 Race Bike Gallery
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