Tell us about yourself!
Thanks for the comment. Counting is done by configuring registers to use the so-called Timer1 in line 57. By default Arduino Uno uses pin 5 as Timer1 input (T1), as you can see on the following picture:http://www.gammon.com.au/images/Arduino/Timer_and_...If you look closely you will notice that on the photo I have my input connected to this exact pin... But if you have another Arduino you may have to consult the interwebs on what is the default pin assignment and where to connect your tacho signal. Please also note you will probably find a lot better frequency counter code on the web (also for your version of Arduino I imagine), this one was written a long time ago when I needed to cobble something together quickly!
Would love to but sold the bike many years ago I'm afraid!