SM is a defunct Polish motorcycle manufacturer founded by Stefan Malcherek.
They produced lightweight motorcycles in Poznań, Poland from 1937 to 1939 and also supplied engines to other manufacturers.
[1] Stefan Malcherek established the SM Workshop in Poznań in 1924, which manufactured a 50 cc auxiliary engine that could be fitted to a bicycle.
The machine debuted at a competition organised by the Unia motorcycling club in December 1937.
Although the competition was won by a German Phanomen machine, the SM was seen to be a good competitor.