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Trobike was a type of mini-bike. Although preceded by the World War II military Welbike and later Corgi for the civilian market, it was one of the earliest to be sold in kit form to avoid purchase tax.

The Trojan Lambretta group was founded in 1959 when Lambretta Concessionaires Ltd took over Trojan Ltd, one of the oldest firms in the British motor industry. At about the time the group owned the Clinton Engine Corporation of Maquoketa, Iowa, USA.

1961 Trojan Trobike



Trobike front mudguard decal

Clinton were world-famous for their engines used in lawnmowers and chainsaws. At this time many were supplied for use in portable generators, paint sprayers etc.

During the late 1950s the British public were becoming aware of the craze sweeping teenage America – karting (or go-karting). The sport arrived in Britain with US servicemen bringing outfits over and even making their own.

At first, the most popular engine was the 2.5 hp 95 cc Clinton engine – being both readily available and cheap. By 1959 Trojan began making the Trokart using this engine. It was sold both in both built-up form and as a kit to avoid purchase tax; it sold for only £25. By 1963 it was estimated that 250,000 engines in the US and 10,000 in Britain had been sold, all for karting.

The first printed mention of the Trobike is June 1960 and the first road test published on Thursday 22 December 1960 in Motor Cycling with Scooter Weekly. The price then quoted was £35 in kit form although two adverts in 1962 quoted £29. This may account for the fact that it was made for road use with front and rear brakes, and also for off road use with a rear brake only.

By November 1961 the factory, also producing the Lambretta scooters, had also tooled up to produce the Heinkel three-wheeled bubble car, then known as the Trojan Cabin Cruiser. It seems that the Trobike was a limited success, with perhaps only 500–600 being sold over the two-year period – the last confirmed despatch being 6 March 1962. Known frame numbers range from TB501 to TB1148.

The very last machines were sold to a farmer and known as the Sussex Miniscooter. Later still, a variant known as the Lowline Chimp appeared, using a very similar frame and again a Clinton engine.

Originally, machines had black handlebar rubbers but some later models were fitted with buff-coloured rubbers. The twist grip on early machines (as appear on factory literature) was manufactured by Amal with the cable entering parallel to the handlebars. Later bikes had the more typical Amal twist grip with the cable entering from below.

Later models were fitted with a bashplate between the lower frame downtubes (by frame number TB879). The bashplate was dual purpose: to stop dirt entering the air filter, and also to protect the carburettor from damage. Even later models (by frame number TB1029) were fitted with a further small light steel plate shielding the carburettor float bowl and fitted under the heads of the front two engine mounting bolts.

Specification

• Manufacturer: Trojan Ltd, Purley Way, Croydon, Surrey
• Model: Trobike
• Wheels: Trojan pressed steel 5-inch (130 mm) split rim with tapered roller bearings
• Tyres: Front 3.00 x 5 Dunlop, Rear 3.50 x 5 Dunlop
• Tyre pressures: 20 pounds per square inch
• Accelerator and Brake linkage: Enclosed cable
• Brakes: two 5-inch (130 mm) drums
• Chassis: ⅞ inch tubular steel, duplex
• Colour: White frame, red mudguards, black seat, yellow engine
• Chain: 3/8-inch pitch x 7/32-inch wide. 105 links
• Engine sprocket: 12 tooth
• Rear sprocket: 64 tooth
• Starter: Recoil
• Cut-out switch: Push button
• Engine: Clinton A490 Panther 2-stroke (de-governed for Trobike application)
• Lubrication: Petroil, 16:1 ratio
• Cylinder size: Bore 2 ¹⁄₈ inches (54 mm), Stroke 1 ⁵⁄₈ inches (41 mm)
• Capacity: 95 cc
• Fuel tank: All-welded ⅜ gall tank mounted on engine
• Transmission: Single speed via Clinton centrifugal clutch
• Electrical: Flywheel magneto
• Suspension: None

Dimensions and weight

• Overall length: 48 in (1,219 mm)
• Width over handlebars: 21 in (533 mm)
• Wheelbase: 37 in (940 mm)
• Height over top of handlebars: 28.5 in (724 mm)
• Seat height: 23 in (584 mm)
• Weight: 60 lb (27 kg)

Performance

• Power: 2.5 b.h.p. at 3800 R.P.M.
• Max speed: 32 mph (51 km/h)
• 0-30 mph: 21 seconds
• Braking distance: 28 ft (8.5 m) @ 30 mph (48 km/h)

Frame. The frame is manufactured from high-quality steel tube which is electrically welded to resist shock and impact. The steering head is mounted on ball bearings to provide ease and smoothness of movement. The front mudguard and the integral rear chain and mudguard are built of resin reinforced glass fibre and finished in red to contrast with the white enamel finish of the frame assembly.

Engine. The Clinton A490 Panther 2-stroke engine is centrally mounted to ensure perfect balance at all speeds. The engine position is adjustable to suit chain tension. The starting is by recoil starter, power being delivered to the rear wheel through an automatic centrifugal clutch which comes into effect upon opening of the throttle.

Models. Two models – the Garden Model and Road Model – are basically similar, with the difference that the Garden Model does not include number plates, front wheel brake and brake lever, hooter or tax disc. Trobikes have an eye-catching colour scheme – white frames, forks, handlebars, and wheels – yellow engines – red chain/mudguards. A foam rubber saddle covered with black plastic leather cloth is fitted to each machine.

Wheels. Wheels are made from extremely strong pressed steel and are of the split rim type for easy tyre removal. Both front and rear wheels run on opposed high-grade taper roller bearings on an alloy steel spindle, which is designed for easy wheel removal. Highly efficient car type internal expanding brakes are used.