Bell 8 function Digital Speedometer for tach?

[Charley Davidson]

Any body know if I can use this for a tach and how to do it?

 

[lens42]

I've seen a few posts on this, but this was first I found when Googling "Bike speedometer tachometer"

http://www.instructables.com/id/Tachometer-made-from-a-bicycle-speedometer-cycloc/

so the answer is "yes'. Basically you play with the tire diameter setting and the number of magnets on the circumference and you can get rpm.