With an experienced team and a lot of data.
Protect your 1957 Triumph T20C Tiger Cub from the unexpected.
In 1952, Triumph re-entered the commuter market after an absence of 13 years absence. Rather than pursue a small capacity two-stroke like Villiers, Triumph instead produced a scaled-down version of the Tiger twin in the 150 cc OHV four-stroke single-cylinder Terrier. Shared styling cues included headlight nacelle, and tank badges. Suspension was by basic telescopic forks and a plunger rear end. The cylinder was tilted forward to align with the frame down tube.
The 200 cc Tiger Cub was launched at the 1953 Earls Court show and proved quite competitive, with 14 bhp at 6,500 rpm, 70 mph and 100 mpg. It weighed only 230 lbs and sounded like a proper motorcycle, with crisp exhaust and valve clatter. In the next 12 years it would be sold in 20 different models, from “bathtub” bodied tourer to sports model, on and off-road dual-sport, barebones scrambler and trials bike. The 1957 Tiger Cub got a new frame with a swing-arm.
These “Baby Bonnies” then got a real shot in the arm in 1960, when “L-Plate” novice riders were restricted to 250 cc bikes in the UK. The Tiger Cub was low and light, and it was enormously successful, with more than 112,000 were sold to 153 different countries between 1956 and 1969. The last three years, however, used Triumph engines in BSA Bantam frames. When looking for a running, ridable Tiger Cub, it’s important to buy a fresh rebuild of a late model done by a knowledgeable restorer. The reasons are numerous, but Edward Turner’s dictum of “building light” was overdone in the Tiger Cub, which was fragile in several important respects.
The top tube was lower than normal, and partially supported by bracing inside the gas tank. The wrong tank could leave the frame unsupported. The right side plain bearing on the crank was poorly lubricated, and the bike required careful warming up. Ridden hard from a cold start, big end bearings could be as short-lived as 100 miles, and dealers were kept busy with warranty repairs.
The primary chain ran in a shallow oil bath and could stretch, damaging the case. It could fail altogether if the level dropped significantly. The crankcase had to be split to change the final drive sprocket and even a chain replacement required a new one be attached to the old. The clutch and gearbox also did not suffer fools gladly.
The Triumph T20R and T20S high-pipe trails and scrambler models were light and effective, but the battery was dropped in place of an energy transfer ignition. That proved to be sensitive to points gap and ignition timing and could be infuriating fragile in competition. One final puzzle involved an hour’s worth of lively running, which would be followed by unexplained coasting to a halt. Overheating was suspected, but never proven.
To be fair, the factory worked hard to correct these problems and the later the bike, the better it is. The Cub gained a roller crank and adequate oil pump in 1966, and modern electronics can replace the defective ignition. The off-road bikes were most successful and are still competitive in vintage events. Any of these diminutive Triumphs, however, is a charming and rewarding bike when running properly, and any collection of small motorcycles would do well to have one.