Another spreadsheet i’ve made, to calculate the speed of your moped at a given RPM. You need to know the details of your engine, gearbox, sprockets and rear wheel. You can find most of it in a spare parts catalogue, or simply count the teeth on all sprockets.
If you want to calculate the velocity for a single speed engine like a Puch Maxi, just type the same value in “1 Gear” in the primary and secondary fields. I’ve made the file up to a 6 speed gearbox.
You can use MS Excel, OpenOffice, LibreOffice or a similar program.