Hello Xermán,
sadly it is NOT possible to upgrade the single speed series to the EVO (Sturmey Archer KS3) drive.
This is simply caused by the size of the bottom bracket; that of the EVO is much bigger.
But it is still possible to retrofit the ATS dual speed drive on all single speed brackets
- and soon also the three speed efneo drive:
https://stridacanada.ca/efneo-gearbox-strida/
