1952-1969 Triumph Tiger Cub: The Baby Bonnie

Best bets on tomorrow’s classics: 1953-1969 Triumph Tiger Cub — The Baby Bonnie


| November/December 2012



Triumph-Tiger-Cub

1953-1969 Triumph Tiger Cub – The Baby Bonnie

Photo By MC Staff

Triumph Tiger Cub
Claimed power:
10hp @ 6,000rpm (14.5hp @ 6,500rpm/Sports-Mountain Cub)
Top speed: 60/70mph
Engine: 199cc air-cooled OHV single
Weight: 250lb (wet)
Price then/now: $650 (Mountain Cub)/$2,500-$4,500

Learn to drive in a Ford, and you’ll likely buy a Ford. Triumph boss Edward Turner understood brand loyalty and the importance of having an entry-level motorcycle in the model range. He also wanted that bike to mimic the premium sportsters in the Triumph range as closely as possible. Enter the 1953 Triumph Tiger Cub.

Derived from the 150cc Terrier of 1952, the Cub’s engine was a 199cc (63mm x 64mm bore and stroke) air-cooled, dry sump, OHV 4-stroke single with an iron cylinder and alloy head. The built-up crankshaft spun on a drive-side ball bearing with a plain bush on the timing side, and started out with a roller bearing connecting rod big end (changed to a plain bearing around 1956). Primary drive to the wet multi-plate clutch was by chain, while the 4-speed countershaft gearbox was housed in a separate chamber cast in-unit with the engine. An alternator powered the 6-volt electrical system, with the ignition points mounted in a housing on top of the timing cover. The engine breathed through an Amal Monobloc carburetor (though a Zenith instrument was also used during the late 1950s). Introduced with “plunger” suspension, the Cub acquired a modern swingarm frame in 1957.

The Cub’s trump card was its styling. Later nicknamed the “Baby Bonnie,” it was designed to emulate its bigger brothers, the Triumph Speed Twin and Triumph Thunderbird, with a similar headlamp nacelle (featuring a nifty mechanical gear position indicator) and similar paint schemes. At half the price of a T-bird, the Triumph Tiger Cub allowed entry to the Triumph range for a basement price. And above all, it looked and felt like a “proper” motorcycle, with a solid 4-stroke thump from the exhaust and lively performance for the time; with a top speed faster than 60mph, it was definitely a cut above all the wheezing Villiers-powered 2-stroke British bikes of the day.

Though cute, the Cub had its scary side. The plain bearing big ends were prone to failure if the engine was revved hard before the oil was warm. A better oil pump was fitted from 1961, and the Cub received a complete new bottom end in 1962, which fixed the problem. Also, the primary chain had no adjuster, and sometimes broke if the case ran dry of oil, and the marginal frame used the gas tank as a stressed member — if a different tank was fitted, the frame could break. Adjusting the ignition points on early models required some dexterity until the ignition plate was moved to the end of the camshaft in 1963.

Along with the stronger engine came a Triumph Sports Cub with 14.5 horsepower — up 4.5 horsepower — giving close to 70mph, while another variant, the TR20 Trials Cub featured a wide-ratio gearbox and a high-level exhaust. It was the Trials Cub that inspired West Coast distributor Johnson Motors’ sales manager Don Brown to propose to Triumph that they build a bike for the California market to compete with the small dirt bikes flooding in from Japan. Brown wanted the Trials Cub’s wide-ratio box and running gear with the Sports Cub’s more powerful engine. The result was the 1964 T20M Mountain Cub with Dunlop Trials tires, aluminum fenders and 7.5 inches of ground clearance. JoMo sold every one they could get, even offering a version with half tracks for winter use in the California mountains.





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