Tachometer for Lathe

[Shuswap Pat]

I am still looking for a simple digital tach system for a lathe. I have added a VFD, and would like to know the spindle speed is. I need a range of 20 to 2000 RPM.
Any simple solution would be appreciated.

[Dr. Rob]

Bicycle computer.

I think. Have one of these that I've never used; seemed like a great little toy for precisely that sort of thing. Measures, counts, tallies... But never actually found a use for it.