The counter used on the JR counter is a Veeder-Root model 745815-001. The manufacturer’s speed limit on these counters is 500 rpm. Since the counter records 10 counts per shaft revolution, this is a limit of 5000 counts per minute. Using a riding constant of 10,000 counts per kilometer this yields a limit of 30 km per hour riding speed, or 18.6 mph.
In Tom's test of the JR, he ran the prototype 500 miles at a speed of 20 mph with no perceptible bad effects. This suggests that the manufacturer's limit is conservative.
The moped in question has an unknown gearing to the wheel end of the drive cable. The speed limit for this moped will have to be found by determining the counts per kilometer of the installed drive. This is easily done, and will provide the user with a suggested limit for his riding speed.
Note: Just talked with Tom. He has already discussed this with the guy, and it appears that overspeed will not be a problem. Efforts will be made to get some photos and operational data.
Experience with previous counters suggests that the weak spot in the counter assembly is the central drive gear bearing, where the big gear rotates against the cup retainer. The counter itself may still be in good shape when the chassis wears out.
See: Counter speed