The Aero Bike
Part One
The Aero Series of Bikes
The AERO bike started out as a styling project featuring an extended aerodynamic front with spoilers and avant garde bodywork. The design was a sleek asthetic shape conforming to the riders body.
Two bikes were constructed from this mould, the first for friend Mike Brosnan and the second as a BEARS race bike for John himself.
Construction of the body shell began in 1985, John Britten sculpting the plug from a block of polystyrene and car body filler. The plug and mould were completed with the help of Bob Brookland, Mike Brosnan and Nick Edwards.
Part Two
The Aero-D-Zero
The first bike, later named Aero-D-Zero, was built around a steel trellis frame and bevel drive Ducati motor of Mike Brosnan in 1985. It was converted into a BEARS race bike by Mike and successfully campaigned in early BEARS events in New Zealand.
The bike was first run in the March 1987 BEARS speed trial, clocking 234.02 kph (145.41mph). It latter won the 1988 and 1990 speed trials with speeds of 242.72 kph (150.82 mph) and 247.80kph (153.98mph) respectively.
Interestingly the front handle bar winglets were found to cause a disconcerting lean at high speed and were clipped during these trials.
The bike featured a petrol fuelled Ducati Darmah bevel drive motor with Imola cams, big valves, standard rods and crank, and in its final spec ran Lectron flat slides. The chassis used Ceriani forks, a steel trellis frame very similar to a modern Ducati and a fabricated aluminium swing arm activating a Koni shock. Magnesium wheels by Morris and Campagnola, Brembo master cylinders, AP Lockheed front calipers, Fontana rear caliper completed the kit.
The initial bodywork incorporated lights, indicators and switch gear but the bike was never road registered. This bike has been recently restored by Mike and is in running condition.
Part Three
The Aero-D-One
After producing the first prototype John took the AERO bodywork and developed a monocoque version, the bike being named Aero-D-One, the first bike subsequently becoming known as Aero-D -Zero.
Initial thoughts were to develop a four valve cylinder head for a bevel drive Ducati motor to power the chassis. A local company, Denco Engineering, with a background in speedway motors was approached in 1986 to determine whether this was feasible. The resulting prototype Denco engine, a V-Twin based on a speedway design of Bob Denson and Rob Selby, was rolled out in 1987.
A composite monocoque chassis was constructed inside the AERO body shell, the new design having a fabricated aluminium swing arm mounted directly to the engine gearbox assembly. An under-slung White Power push-shock arrangement completed the rear suspension. The body bolted directly to the heads and swing arm pivot, the steering head being bonded directly into the composite bodywork. The influence of top GP motorcycle technician Mike Sinclair, also of Christchurch, can be seen in the chassis and its GP specification componentry: White Power forks and mono shock, AP Lockheed brakes and Marvic magnesium wheels.
The monocoque was constructed in unidirectional carbon-fibre, kevlar cloth and high density closed cell foam and incorporated an integral fuel tank and internal ducting for engine cooling. The mould was made up of 26 separate sections with the finished monocoque weighing in at 12kg. This was attached by inserts to the cylinder heads and swing arm pivot making the engine semi-stressed. The bike was put together under the guidance of mechanic Allan Wylie and was first ridden in 1987 and ceremoniously dropped by John attempting to turn around in Carlyle street outside the present Britten Factory.
Initially the bike had many problems not the least being the inaccessibility of the monocoque design - the bike had to be split in two to access the motor. The bike was first raced at a local BEARS meeting in March 1987. The motor had plenty of torque, enough to make it a handful, but would not rev freely.
The heads from this motor were subsequently sent to Jerry Branch in California who made valuable suggestions on their redesign. New heads featuring straightened inlet ports and a new cylinder design were constructed, the rear head being turned around so both carburettors faced the rear. Bore and valve sizes were altered to produce a freer revving motor.
| SPECS of the AERO-D-One |
Engine: Air cooled, 60 degree V-twin four stroke. Belt driven DOHC, four valves per cylinder. Compression ratio 13.5:1 on methanol fuel. Unit construction cases with dry sump.
- Capacity 999cc. initially 87x84mm, finally 94x72mm
- Output claimed 120bhp at 9000rpm
- Carburation modified 40mm Amal Mk2 smoothbore
- Clutch wet multi plate
- Gearbox 5-speed XJ 650 gearbox, removable Ignition Phelan chainsaw magneto ignition
Chassis: Kevlar/carbon composite monocoque with semi stressed engine. 18" Marvic front and rear wheels.
- Steering 25.5 deg head angle, adjustable trail.
- Suspension front: White Power upside-down 54mm forks rear: White Power monoshock mounted under engine
- Brakes front: 315mm rotor with Lockheed four piston caliper rear: 250mm rotor and two piston caliper.
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Wheel Base 1425mm Weight: 130kg
The new Denco motor made more top-end power and was much more tractable. It was also more reliable after initial problems with oil supply systems had been sorted out. The result was a very quick bike, Kiwi international rider Gary Goodfellow going very close to breaking the lap record at the local Christchurch track, Ruapuna. Gary also raced the bike in the 1988 Dunedin street races winning two and crashing out of the third race with a seized gearbox. This MarkII bike won the 1987 BEARS speed trial clocking a speed of 238.52 kph (148.21mph).
The bike was retired from racing after breaking a gudgeon pin at the 1988 Sound of Thunder Meeting. It currently resides in the basement of the BMC factory awaiting restoration.