Counter Sprocket Drive for Speedo

I got this idea from this site as one of the project bikes had done this to be able to reuse the original mechanical speedometer by driving it off the counter sprocket. Does anyone have any additional knowledge on how to achieve this?

What do you mean by counter sprocket? The Fr drive chain sprocket?

martin_csr wrote: What do you mean by counter sprocket? The Fr drive chain sprocket?

I'm guessing he means the countershaft (i.e. front) sprocket.

Just noticed that you supplied that answer but the text color was changed to white for some reason. Why would you do that?

(color=white)The Fr drive chain sprocket?(/color)

Yes, front sprocket or off the chain. Just looking to see if I can retain the stock mechanical speedo.