Auxiliary engined pedal bikes

Probably as cheap a
transportation one can
get without buying
a ticket

and you wont get one either
Although attaching a combustion engine to an ordinary pedalling bike really was the prototype of the "Motorcycle" these early models were quickly developed into proper purpose built strong, fast
and reliable transportation. From time to
time history has repeated itself
and inventors has tried again
for a cheap simple form personal
transportation.
This also often coincided with
the authorities' demands for changes
in taxation, insurance rules
and demands for changes
in driver's licence classes.
In the thirties the little 50cc
two stroke engine would
be excepted of
any taxation and
insuring rules. The two
stroke development had made
them reliable enough
to last for a while

This model is a (probably) 1937 Danish made Totaco ridden by someone who really appreciated the excempts from the current age limits on drivers' licence at his age. He really kept fit!!
Most other makes became popular in the fifties like the German ILO or the Danish Diesella.