The Complete Guide to John Britten’s Aero-D-One Motorcycle
- 11 July 2017
John Britten, legendary motorbike designer from Christchurch, made four motorcycle models in his short life. Classic Motorcycle Mecca proudly displays three of four of these Britten motorcycles, kindly on loan from the Britten family themselves. Each one of them was successful in its own right: John Britten’s V1000 model impacted motorcycle design internationally. The dynamic Aero-D-One was the second bike John Britten designed and it included a New Zealand-constructed engine. After a few adjustments it took the New Zealand racing scene by storm. This post looks at the Aero-D-One from its conception to its components: a complete guide.
The Aero-D-One started out as styling project for John Britten, featuring an extended aerodynamic front with spoilers. John Britten designed a sleek aesthetic shape which conformed to the rider’s body. Two bikes were constructed from the same mould, the Aero-D-Zero for engine builder Mike Brosnan and the Aero-D-One for John himself.
In 1985, with the help of two friends and Mike Brosnan, John Britten sculpted the fairing, which is an external structure to help streamline the bike. The fairing was important because this bike was to be the most aerodynamic bike John Britten could possibly create. It was called Aero-D-One after all.
The Aero-D-One was put together under the clever guidance of mechanic Allan Wylie and influenced by top GP motorcycle technician Mike Sinclair. It had a monocoque chassis that was attached to the engine by the cylinder heads.
To access the engine, six bolts had to be removed and the whole thing split in two. It made any maintenance difficult.
The story behind the engine would make any Kiwi proud. The engine was going to be a Ducati engine but John heard of a new engine produced for speedway sidecar bikes by local Christchurch company Denco Engineering. John approached them to see what they had. They made a prototype based on a speedway design of Rob Denson and Rob Selby. It impressed John, so he put the engine in the Aero-D-One and it definitely paid off. The Aero-D-One was a fast bike.
Unfortunately the Aero-D-One had a troubled start. During the Aero-D-One’s first ride it was dropped by John Britten when he attempted to turn around in Carlyle Street!
That was only the beginning. The motor provided plenty of torque - but it did not rev freely. So the engine was sent to Jerry Branch in California who made several changes: the cylinder head design was revised, the rear head was turned around so that both carburettors faced the rear and the bore and valve sizes were changed. The changes worked and the engine began to rev freely!
The next problem was the aerodynamics. At the 1987 trials the winglets caused the bike to lean one way or the other and run anything but upright. They were removed and the problem was fixed.
The Britten Aero-D-One flourished on the race track. It was first raced at a New Zealand BEARS meeting in March, 1987. It raced alongside the Aero-D-Zero, John Britten’s first bike. The Aero-D-One beat it, taking the top spot with a speed of 148.21mph (238.5kph).
It also came very close to breaking a lap record at the local Christchurch track, Ruapuna. It also successfully raced in the 1988 Dunedin street races. It won two and crashed out of the third race with a seized gearbox.
It was retired from racing after breaking a gudgeon pin at 1988 Sound of Thunder meeting.
Engine: air-cooled, 60-degree, V-twin, four-stroke. Belt-driven DOHC, four valves per cylinder.
Compression ratio: 13.5:1 on methanol fuel.
Bore & stroke: initially 87x84mm, 94x72mm after re-tune.
Output: claimed 120bhp at 9000rpm.
Carburation: modified 40mm Amal Mk2 smoothbore.
Clutch: wet multi plate.
Gearbox: 5-speed XJ 650 gearbox.
Ignition: Phelan chainsaw magneto ignition.
Chassis: Kevlar/carbon composite monocoque with semi stressed engine. Steering 25.5 degree head angle, adjustable trail.
Suspension front: White Power, upside-down 54mm forks.
Suspension rear: White Power, monoshock mounted under engine
Brakes front: 315mm rotor with Lockheed four piston caliper.
Brakes rear: 250mm rotor and two piston caliper.
Wheels: 18” Marvic.
Wheel Base: 1425mm.