Using a basic non cadence computer to read cadence

[Cruzer]

I have asked this before but I cannot find the thread nor responses any where-

 

I have a VERY old Siemens VDO tourist bike computer which I want to use on my spare bike in my indoor trainer. Since most training plans etc revolve around Heart rate and Cadence (and power) I would like to jippo this computer to read my cadence.

 

Does anybody know what settings (Tyre size or relevant code) to input in order to achieve this? 

 

My Cranks are 170's

 

Looking forward to hearing from the brainboxes out there.

 

 

[Dibles]

https://www.bikehub.co.za/forum_posts.asp?TID=30118&KW=cadence

[Cruzer]

Thanks Mandibles!!