1973 Triumph 850cc 'Rob North' Trident

Although upstaged in the showroom by Japanese rivals, the Triumph and BSA 750 triples did more than enough on the racetrack to ensure their place in motorcycling history. BSA-Triumph's Chief Engineer Doug Hele spearheaded engine development throughout 1969, while frame builder Rob North devised a chassis that would stand the test of time like few others. The team narrowly missed victory at the 1970 Daytona 200, its first major event, Gene Romero finishing 2nd on a Triumph. Dick Mann's BSA won at Daytona in 1971 and John Cooper, also BSA-mounted, at Mallory Park's Race of the Year, vanquishing the hitherto unbeatable combination of Giacomo Agostini and MV. Percy Tait and Ray Pickrell had won the 24-hour Bol d'Or endurance race the preceding week on another Triple, and Cooper wrapped up a memorable international season for BSA-Triumph with victory in the 250-mile race at Ontario in October.

Financial difficulties meant that there was no works effort in 1972, but privateers kept the BSA-Triumph Triples winning for many years and they remain a potent force in Classic racing today. Miles Engineering later acquired the rights to the North chassis and continued production. The manufacturing rights have changed hands a few times since then and are now owned by Les and Denise Whiston, for whom the frames are expertly fabricated by Mick Pearce.

Inspired by the wailing BSA and Triumph Triples, particularly during the Easter Transatlantic Trophy races between Great Britain and the USA in the 1970s and '80s, our private vendor promised himself that one day he would own one. Inspired by a magazine article speculating on what might have happened if BSA-Triumph had offered a single-seat production model using the North frame, he decided to build his own. He duly purchased a Rob North-type frame, which had been numbered with what appears to be the transplanted section of an original Triumph frame. The frame came with matching crankcases and a logbook. The vendor had already purchased a complete engine via a work contact, who had had it under his bench for 20 years. When the North frame and matching crankcases turned up, he was too far down the road with the engine rebuild and so those crankcases were not used. However, they are available via separate negotiation with the vendor, should the successful purchaser wish to rebuild the machine with matching numbers.

The engine was completely rebuilt to racing specification with all new bearings and 850cc cylinder barrels and 9.5:1 pistons. The original crankshaft was lightened and fully balanced, and lightweight racing steel con-rods fitted. 51B cams with R followers were used together with new valves, guides and beehive racing springs, fitted in the ported cylinder head.

The primary drive is standard, as is the clutch, while the gearbox internals have new bearings. Carburation is by new 30mm Amal Mk1 carburettors. Ignition is a Pazon system, with electrical power from the standard alternator and a Boyer voltage regulator. The lights, etc comprise some replica and original Lucas equipment including the handlebar switches. The fuel tank is the slightly larger Rob North American style, while the seat is the smaller Rob North British style.

The rear wheel has a wide XS alloy rim built onto a standard T140 conical hub. The front forks are replica Ceriani with a magnificent 250mm four-leading-shoe replica Fontana brake, likewise laced to an XS alloy rim. (The Fontana was selected because the Rob North factory bikes used them for the first season prior to changing to disc brakes.)

The Trident was finished in the summer of 2025 and is not yet fully run in. It has been ridden around the Isle of Man TT circuit and won the 'Best Road Bike' award at the 'Jurby Sunday' gathering during the Manx Grand Prix. Accompanying documentation is limited to a V5C Registration Certificate, which records the frame-matching engine number and not that of the unit currently fitted ('T150VHJ1921'). Accordingly, prospective purchasers should satisfy themselves with regard to this motorcycle's history, authenticity, originality and condition prior to bidding.

The success of the modern Hinckley-built Triumph Speed Triple amply demonstrates the appeal of a 'naked' superbike. A credit to its creator, this remarkable motorcycle would have been well within BSA-Triumph's capabilities back in the 1970s, and it remains baffling why such a machine was not put into production. After all, the major components were already in existence; all they needed to do was tool up for the frame, tank and seat. Yet another lost opportunity...
Offered with key