Evening,
I know I’ll get hate mail for suggesting it but if you have no luck you can always use a modern bicycle speedo, I have seen these on vintage bikes (I am certain that there were some in use at the Banbury Run last year!)as they are very small and not too noticable plus are quick to fit/remove.
These cost less than £30 unlike several hundred if you can find an original! They also record trip distance, time and average speed (dependent on the model, check specification if in doubt). A wireless one is probably best as the wire could get trapped.
James
