Lady BacFire...

[Chris.Dallas]

Using a Riley v Twin crankcase if I remember correctly!

[Austin in the Shed]

The black GN Howard belongs to Duncan Pittaway,one of a collection of exciting cars he owns.That trials special is 3.2 litre using a British Anzani vee twin crankcase apparently.

[Dirk73]

on the original question, the engine in Rob Beck's creation is a french BAC V-twin (hence Mrs BACfire) these were used in purpose-built pacer bikes that would tow cyclists up to ludicrous speeds on boardtrack velodromes in the quest for obscure records. The potential for splinter injuries alone makes ones eyes water just thinking about it...

[Lowespeed]

Pacing motorbike at Montlhery. Note drive gearing, handlebars, and foot rests
   

[Greig Smith]

These are termed Derny bikes and the idea is to be paced up to speed on the track on your bicycle. At the back of that extended frame is usually a roller which will rotate if your front tyre hits it while you are tucked in. The handle bars of the Derny are swept back to get the rider to sit up straight to afford maximum protection for the track cyclist behind.

Being towed over 50mph on a bicycle isn't for the faint hearted, let alone being towed up to world record speeds wearing a simple lycra outfit. The belt drive ratio limits the top speed of the Derny.

The potential for loosing skin increases exponentially as the top speed increases....

Aye
Greig