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Triumph Tiger Cub – The Baby Bonnie 1954 to 1968

The Triumph Tiger Cub was affectionately known as the Baby Bonnie and was in production from 1954 until 1968. It’s a testament to Ed Turner’s design that plenty survive today and the Tiger Cub remains a favorite entry into classic bike ownership.

Triumph Tiger Cub History

1967 T20 Triumph Tiger Cub
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Triumph Tiger Cub T20 (1967) by SG2012 is licensed under CC BY 2.0.

To understand the Triumph Tiger Cub we have to rewind back to just after WWII and secondly we have to get into Ed Turner’s mindset at the time, luckily we are here to do both for you.

Just after WWII, Triumph’s Chief Designer (legendary Ed Turner) was set to be heavily focused on twin cylinder motorcycles with increased power and capability being a bi-product of that focus. 

However, there was also a massive market for lightweight commuter bikes that were four-strokes as opposed to two-strokes. 

Wanting to stay current and at the top of the game in Britain, Turner sat with his pen and paper and designed the T15 Terrier, a small four-stroke single, that was very handsome, classically styled, and ran against bikes like the BSA Bantam. 

Only producing 8 horsepower it was enough to compete and fit right into the niche in which it was intended.

The Terrier was the first Triumph to use a rear plunger rear suspension and this was paired with telescopic forks that had only been introduced after the war. While riding directly into the future the bike remained a fundamentally Triumph motorcycle with the distinctive Triumph frame, headlight nacelle and knee pads. 

It was the Terrier that was Triumph’s first unit construction OHV engine. This would form the basis for many BSA single cylinder designs that would come later. 

The T20 Tiger Cub was essentially a larger capacity Terrier and took that unit construction design and made it that bit bigger so it was a more capable motorcycle on the road. 

The Tiger Cub Engine

The Triumph Tiger Cub engine
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The Triumph Tiger Cub engine

The unit construction is what made the Terrier and Tiger Cub stand out from the rest of the pack and was the design that set the precedent for the future of single cylinders. 

The engine therefore consisted of a pair of crankcases split vertically, housing the crankshaft in the front and four-speed gearbox in the rear. 

It was the right hand side of the engine that was the most unconventional, where oil was pumped into the bearings and a combined bevel drive and toothed pinion were fitted. 

The toothed pinion engaged with a larger one on the end of the camshaft above which in turn operated the pushrods, which operated the inlet and exhaust valves. 

The gearbox, timing pinions and oil pump were all enclosed by an inner timing cover mounted just below the drive shaft. 

On the left hand side there was a pretty standard crankshaft sprocket driving the clutch sprocket by a single primarily chain. 

Lucas electrics were fitted which consisted of an alternator, rectifier and ignition coil that was not in line with other Triumph’s of the time. All of the left hand side was enclosed in a sculpted casing that had the Triumph name embossed on it. 

The cylinder was forward sloping parallel to the front down tube and the two overhead valves sat in rocker boxes cast into the cylinder head. 

Initially the engine was fitted with an AMAL carb that had a detachable float chamber but in 1959 this was switched to a Zenith MXZ-C17 Carb that had its own air filter. The change was not considered favorable. 

The bore and stroke of the Cub was 63 x 64mm as opposed to the Terrier’s 57 x 58.5mm aside from that everything else in the engine department was identical. 

Generally there are considered to be two versions of the Triumph Cub, the early versions that shared the frame and forks with the preceding Terrier model up until 1957. 

Then there are the models that came after up until 1968 which were developed to be more in line and practical with bikes of the time. 

For late 1957 the Cub received a new frame which had a swing arm with twin shock absorbers as opposed to the plunger type suspension previously shared with the Terrier. 

There was a separate sub frame that held the seat, rear mudguard and top mounts for the shocks which were bolted to the main frame and either end of the swing arm. 

For some, an unfortunate styling change came in 1959 which lasted until 1962 and that was a ‘bathtub’ enclosure which uniformed the Cub in line with the bigger Triumphs of the time that were suffering at the hands of the same styling.

Triumph Tiger Cub 1962
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This VGC 1962 Triumph Tiger Cub with bathtub enclosure was sold by Bonhams in 2014 for just £1,265

However, it wasn’t as bad as the full enclosures seen on the bigger bikes and mainly covered the front part of the rear wheel, it is referred to now as a bikini cover. 

In 1964 the bikes engine was re-designed to eliminate the distributor and until 1965 the Cub remained with over 100,000 Cub’s estimated to have been produced by this point. 

In 1966 the Triumph Cub was mated with the BSA D7 Bantam which gave it the new title Triumph T20B Bantam Cub (not very catchy). 

The benefits of pulling parts from BSA meant the frame was stronger and it had a longer wheelbase. Later on the Cub was mated with the D10 Bantam frame and the T20B Super Cub was born. 

However, the Triumph/BSA hybrids were not popular with the public and are not considered a commercial success. 

Triumph Tiger Cub Specs

Engine and Transmission

  • Engine – Four-stroke, single-cylinder, OHV
  • Capacity – 199cc
  • Bore x Stroke – 63 x 64mm
  • Compression Ratio –  7:1
  • Cooling System – Air-Cooled
  • Starting – Kickstart
  • Induction – Amal Monobloc Carburettor
  • Transmission – 4 Speed
  • Final Drive – Primary Chain
  • Max Power – 10 horsepower at 6,500rpm (14hp for the S version)

Chassis and Dimensions

  • Frame – Swan Neck
  • Front Suspension – Telescopic fork
  • Rear Suspension – Swingarm, twin shocks
  • Front Brakes – 5.5” Drum
  • Rear Brakes – 5.5” Drum
  • Dry Weight – 95kg
  • Wheelbase – 1245mm
  • Fuel Capacity – 13.6L
  • Rake Angle – 65 degrees
  • Seat Height – 29”
  • Ground Clearance – 5”

Triumph Tiger Cub Performance

It is safe to say that Turner’s original designs for the Terrier and Cub were successful and they held some merit with the public as being great commuter bikes offering 90mpg in careful circumstances. 

They were affordable and yet didn’t look weak or cower under the bigger bikes shadows which made them very popular, particularly with the youth of the time. Practical bikes with style are a winning combination to date. 

However, it wasn’t just the standard Cub that was a hit, from the jump competition riders could see potential in the lightweight single to compete in various races and so competition style variants made their way to the market.

It was in 1957 that the first T20C competition models were first produced with 18” wheels, no center stand, a high level exhaust for better ground clearance and a smaller gas tank.

Triumph Tiger Mountain Cub
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Triumph Tiger Mountain Cub

As Classic Bike Guide puts it “The Trials Cub became a huge success, with the field at many a weekend competition packed with the tiny Triumphs. The Cub remains a stalwart of pre-65 trials competition. The various Triumph Sports Cub models, objects of desire in the showrooms for many a young rider, had 14.5bhp, up 4.5bhp on the base models, giving top speeds of nearly 80mph.”

The T20C was replaced by the T20S Scrambler and joined by the T20T Trials Cub and T20SL Scrambler Lights in 1961. There would also be a T20SS Street Scrambler and T20SH Sports Home model later on. 

US dealers started pressuring for a competent trail bike to compete with the Japanes over the dirt. In 1964 Triumph responded with the T20M Mountain Cub that had Dunlop trials tyres, alloy mudguards and even more clearance. 

It was heavier than the Japanese scramblers but had more pull for hill climbing, still going when the Japanese models ran out of puff, plus it was more comfortable to ride. 

The T20M Mountain Cub is likely the most sought after Competition Cub today. 

Buying an Original Triumph Tiger Cub

Prices in the UK for a Tiger Cub start from £3,000 and reach up to around £5,000. 

In the US prices start at around $3,000 and shoot up to $7,000. 

The variation in price is caused by the specific model being advertised and the bike’s condition. 

For example this 1964 Cub in Sturgis has an asking price of $6,500 but is in really good condition, contrarily this Trials Cub raced in the Isle of Man TT is a sporty race pedigree model asking for the same money.

In the UK this 1964 Trials model was recently restored by a Triumph engineer and the asking price is just £4,200. 

Equally this road-going 1963 model looks immaculate and the asking price is only £3,195.  

Restoring a Tiger Cub

Choosing to restore a Tiger Cub is a good option as there were plenty sold at the time and there are plenty on the market today which makes picking up a donor bike and parts relatively easy compared to restoring some other early Triumph’s.

There is a 1962 Cub with matching frame and engine numbers advertised on Car and Classic for £2,250 which has most of what you would need to put it back together and get it running again. 

There has been a resurgence in recent years of classics competing in throwback style racing events, so there are a lot of Tiger Cub Trials style projects on the market that you could pick up cheap and either restore to original condition or use as a build for your own racer. 

For $495 in California there is a frame and engine project going that has the very bare minimum needed to get started if you want more of a back to basics hardcore project to get stuck into. 

Triumph Tiger Cub Spare Parts are a good source for parts for your restoration and prices are reasonable. 

Is The Tiger Cub a Good Investment?

Classic British bikes on the whole are always a good investment, now there are some exceptions to this of course, but the Tiger Cub isn’t one of them. 

It is a popular model that is easy to work on, easy to get parts for and with the resurgence of classic racing events the Trials versions are even more sought after. 

Original condition models are increasing in value as they are getting harder to find, so investing in one of these is a good way to keep some money safe while having a very good looking baby Triumph in your possession. 

Verdict

When you think of Triumph and Ed Turner your mind instantly goes to the Bonneville. 

Well the Terrier and Tiger Cub have just as much of Turner’s magic in them as the Bonnie and they are just as classic in their design and style. 

I have just sent a couple of project options to my partner in an attempt to get him to agree to make some space in the garage for a little Tiger Cub. There is always space right? 

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