Triumph Trials Cub

Owned by Rod

The Trials Cub

From the big box of Tiger Cub paraphenalia comes the bits needed for a Trials Cub. Rod has enough bits for about 73 Tiger Cubs in his boxes hidden in the shed, but the first Cub to be built is this one in trials trim.

A pair of TS20 crankcases with mostly standard Tiger Cub internals, except for a 9:1 piston for a bit more difficulty in starting the thing. The engine is a distributor model from about 1961 with a square barrel and head. The petrol is fed through a Monobloc carburettor which is a period item.

 

 

 

 

 

Engine and carb

Front view of the forks

 

The frame is standard Tiger Cub, but the forks are suspected to be a melding of Triumph twin stanchions into Tiger Cub sliders. The frame has been modified to accomodate an inside the frame exhaust system. The frame tube was bent using a shed made jig and spare frame tube. All welded up, who would suspect it wasn't an original factory competition item? Well maybe to the trained eye!The bike also sports an original Sports Cub oil tank .

 

 

 

 

 

 

Sports Cub oil tank in situ

Frame modification

 

 

The rear wheel rim is a Borrani laced onto a Tiger Cub hub with nobbly tyres on both wheels. Seat is a trials single seat and the petrol tank is from a standard road Cub. The mudguards are lightweight alloy, but what else would you go for?

 

 

 

 

 

 

 Exhaust system inside frame tube

 Jig used for frame bend

 

 

There are great plans for this Cub as parts become both available and affordable. A Triumph Terrier tank is preferred rather than a Sammy Miller item for period looks, although a modern ignition system would not be refused. Ignition is provided by way of battery and coil without a charging system as we do not envisage any round the world trips on this.

It was built up from parts in the shed and cost almost nothing to construct. Our kind of motorcycle!

We are indebted to Allan Thom for the loan of his Husquvarna tank which was intended for Numero uno. This alloy tank and bits have been polished up and looks magnificent. We tried it out on the trials cub which looks respendent in alloy and black.

 

Monochrome splendour!

Having lain about for a bit, it was re-assembled with the bits nicked for other projects and started up. Noise in the shed again! A bit of polishing and rumour has it a road test took place. We replaced the rather hefty car coil for a Jap bike item and that seemed to cure the misfire that had developed, so a very successful evening.

 

 

 

 

 

 

 Husky tank side view

 

 Rear view of Cub - nice slim tank!

 

 

The current battery box is a cut off spare Suzuki item, and it has to be moved out from the frame to enable the battery to be removed for charging. Rod, as ever needed a more elegant (and lighter) solution. A new aluminium box was constructed and rivetted to two posts attached to the frame. The battery is held in by two rubber straps (aka inner tube) and is now quick detach! The seat has been put on properly again and it looks ready to annoy the neighbours!

 

 

 

 

 

Lightweight QD battery box                Ready to go!