Triumph Tiger Cub T20

THE 199cc T20 TRIUMPH TIGER CUB

was introduced in March 1954. Priced at £127 (a little over half the cost of a new Triumph 6T Thunderbird), it supplemented (and then superseded) the 149cc T15 Triumph Terrier; the company’s first post-war single.

The T20 Tiger Cub brief was clear and straightforward. It was to be a small bike with BIG pretensions. Or, if you prefer, BIG aspirations. A bike that filled a gap at the low end of the range. A bike that capitalised on the appeal of Triumph’s established muscle machines (the 498cc Speed Twin and Tiger 100 and 649cc Thunderbird), but with lightweight, commuter—and even boy racer—appeal.

The T20 Cub was also intended as an antidote to the fog of British two-strokes smoking up British streets. Which was no small consideration in view of the Great Smog of December 1952 which quietly—and perhaps not so quietly—murdered around 4000 people.

The 149cc T15 Terrier had shown the way. The T20 Cub gave the Terrier the extra bark it needed.

Edward Turner

Triumph supremo Edward Turner (pictured above aboard a Terrier), typically, oversaw the project and wanted to kick BSA’s Bantam into touch. But it was Turner’s right hand man (and “pencil”), Jack Wickes, who translated the raw engineering numbers into a motorcycle that people actually wanted to swing a leg over.

And there were plenty of takers. Between 1953 and 1969, Triumph built and sold 113,671 Tiger Cubs (including Terriers) and mobilised thousands of teenage tearaways desperate from relief from the gritty poverty of a Britain still reeling from the victory of war.

With its svelte looks, its simple unit-construction engine and affordable price tag, it was a bike that could shamelessly nudge up to its bigger brothers at the local transport café, and stay with the pack all the way to around 65mph, given favourable conditions.

It was frugal too, returning around 100mpg; an important marketing lever in an age where a young man’s wage was typically around £3-£4 a week with petrol costing around 4 shillings (20 pence) a gallon.

Cub engine

The unit construction Tiger Cub engine, with its bore of 63mm and stroke of 64mm was originally designed to allow the extraction of the crankshaft with the engine still in the frame (via the drive/left side), but this was changed within a few years to a conventional split-case arrangement.

The flywheel was a pressed-up item driving two timing gears (one integral with the camshaft). The cylinder itself was made of cast iron and angled forward (in a racy style that, it’s said, Turner was not fond of). A chrome-plated tube carrying the two pushrods is typical of Triumph’s thinking and runs on the right side of the cylinder barrel between the crankcase and cylinder head.

The gearbox is a conventional four-speed unit housed in a separate crankcase compartment. All cubs have right-side gear change. Clutches are wet multiplate (3 plain, 3 friction).

The original carburettor was a specially designed Amal 332. But this was replaced in 1958 with a Zenith, and then replaced again September 1961 by an Amal Type 32 unit—which is what you’ll find on most Cubs today.

Early Cubs feature a points-housing (sometimes referred to as a distributor) on the top/right side crankcase behind the cylinder barrel. But from September 1963, this was deleted and the points were relocated on the right side of the engine on the timing cover.

Tiger Cub production

All Cubs were built at Triumph's Meriden plant with 6V electrics, the power supplied by a crank-mounted alternator charging system. But many, if not most, modern examples have since been converted to 12V for improved reliability. The alternator sits on the left side of the engine in the primary case oil-bath.

Engine power varies substantially depending on the specific model, ranging from 10-14.5bhp @ 6000-6500rpm. Compression ratios also vary between 7:9 and 9:1.

Early Cubs employed plunger rear suspension. But from engine number 26276, swinging arms were introduced.

Cubs are in roaring demand these days, with prices ranging from around £1200 for a decent T&T runabout to as much as £4000 (asked) for a concours restoration. That’s big money for such a small bike. But on the plus side, this is an easy to live with classy lightweight with good handling, decent brakes, and enduring good looks. Hinckley Triumph may be missing a trick by not introducing a modern Cub of their own.

The last model, the T20 Super Cub (aka Bantam Cub), was produced in 1969. Part BSA Bantam and part T20 Triumph, these are attractive bikes and perform well, but they're along way from Edward Turner's vision, and they lack the charm of the original design.

Ownership tips

1. Check engine and frame numbers. Tiger Cubs are frequently "lashed up" from spare parts - which doesn't necessarily create a bad motorcycle. But such "lash ups" will affect resale value.

2. Ignition systems are a weak point and need regular maintenance. It isn't difficult to learn to set contact breakers (points), but it is vital that it's done accurately if you want to keep up with modern traffic (or at least not fall too far behind.

3.Cubs with swan neck frames require the correct fuel tank for structural support. Modified or non-standard tanks risk compromising integrity.

4. Early plain-bearing engines need warming before riding in anger, so take it easy for the first few miles.

5. Plunger-framed models need to have the plungers checked and greased every 1000 miles or so.

6. Use a straight 30-weight oil, or an ordinary non-synthetic multigrade, and change it every 1000 miles.

Owner's story: Jeff Garrett

“I used to be a quality assurance auditor for a pharmaceutical company. One of the last projects I worked on were clinical trials for Viagra. Seriously. There’s a thing called the “first in man” program. Just as it sounds, that’s when the drug is tested for the first time on human volunteers – who, curiously enough, often turned out to be firemen, as if all that rushing into burning buildings wasn’t enough risk for one day.

“Anyway, Viagra was in fact developed as a medicine for various heart conditions and had nothing to do with impotence - and was certainly not a recreational drug. It was only when the 10-12 volunteers were lying in their beds waiting to have their daily readings taken that people noticed a … well, another side effect.

“But I’m retired now and those days are done. I get my personal excitement with my 1961 T20 Tiger Cub that I picked up some years ago. It was partially restored but needed finishing. I stripped the bike and refurbished it – and spent a lot of money in the process; probably more than it’s currently worth, but it was worth it.

 “Tiger Cubs are growing in popularity, and the days of picking them up cheaply are gone. Today you can expect to pay up to around £3500 for a top quality example, such as mine.

“And riding the bike is just great. It’s light, has good handling, and surprisingly powerful brakes - much better than you’d expect. Also, it’s got a very distinct crack to the pattern exhaust that sounds wonderful on the move. Who needs Viagra when you're riding a Tiger Cub?

"It used to have a Zenith carb fitted (which I’ve still got), but it was worn, and Zeniths aren’t available anymore. So I fitted an Amal 626 which was a great improvement. Fuel economy is pretty good, but I haven’t got an exact figure for it. I use unleaded fuel with Redex lead replacement additive.

“I’m heavily involved in the Deal & District Motorcycle Club, by the way. We’re about 100 strong and are fairly active. You can get more information at: www.ddmcc.co.uk. See you sometime maybe.”

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