Longbikes with electric power-assist go back at least to 1898:
The confluence of extra-human power and elongation of a bike’s wheelbase isn’t accidental. Many people’s first reaction to my product, coupled closely with Xtracycle’s, is whether they can have it without the Xtracycle. They think it looks funny, or they are not enthused by the functional synergy of power assist with passenger and cargo capacity. Finally, they don’t see how the elongation is essential to good performance.
In 1978, a US patent was issued for the following design:
The text of the patent notes:
…when modifying a standard bicycle to electric assisted power (adding a storage battery and an electric direct current motor), inherent difficulties exist in providing such with a desirable and adequate combination of weight balance, power, top speed, ease of operation, and range….
The text goes on to enumerate many advantages of an elongated bike format, not least of which is affordance for the motor to engage the bicycle’s transmission instead of a wheel directly as in most electric bike designs. Nearly all of these considerations apply to Stokemonkey’s design as well.