I am planning on using the 1.9mm shaft OD motor here: DC Motor N20 Large Torque Motor Gear Motor with XH2.54 2P Cable for Smart Car DIY|DC Motor| - AliExpress

I have done plenty of research but can't figure out how to choose a flyback diode. Is there a formula? What variables should I calculate and how? I am looking for an SMD diode, not PTH.

Specs of motor:

1.9mm D type

- No-load speed: 92RPM @ 3V, 195RPM @ 6V
- No-load current: 60mA @ 3V, 70mA @ 6V

Any help appreciated!