In the early 1970s there were not a lot of options for speedometers that were not clunky. There was the cable driven version by Huret and the “wheel” driven IKU unit (rubbed against the tire).
Introduced in the mid 1970's, the Erisman Pacemeter was the first 'electronic' bicycle speedometer. Powered by a battery, it used dial meters to display MPH and RPM. I purchased one and was very happy with its performance. It came in very handy for time trials (25 miles back in the day).
These units were also used by top U.S. riders of the time. Additionally, a Pacemeter was used on the Gossamer Condor that won the Henry Kremer prize in 1977.
This listing includes two head units and enough connectors/sensors to set up both (please read further about head unit condition).
Buy this rare speedometer here. It is more or less ,one of a kind. Very hard to find. The original cyclometer for sale. Pre-Electronic. See more bike products for sale ... Bye!