Looks good, Tom. It's nice that the counter will be oriented correctly for the rider to see without cranking his/her head sideways.
Have you tried it on a number of different bike wheel/forks?
What is the gear ratio? I can't see all the teeth but it looks like 11 teeth on the small gear and, perhaps, 33 on the large one resulting in a count of 30 for each revolution. Sounds good.
Alan