Check the listing for details. RARE, Vintage 1970's Erisman Pacemeter - First Electronic Bicycle Speedometer. Color: Black, Condition: Used. Listed at 795.00 USD. 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). The original, out-of-the-box unit had speaker wire connected to the sensor (extra wire was simply bunched up and taped out of the way). I came up with a better idea: Install 1/8” mono phone connectors under the unit so you could remove the unit when not in use, or transfer between bikes. The wires and sensors stay on the bike. I have hooked up my original unit and it STILL WORKS!!!!!!!!!!! When the Pacemeter was first introduced, the sensor brackets were made for standard steel forks (MPH sensor bracket) and 1-1/8” seat tube (RPM sensor bracket). The three “MPH” magnets mounted onto the spokes (around 63 mm from hub center – still a lot of high flange hubs in use at the time). The “RPM” magnets were a press fit into the chainring bolts (at the time Campagnolo was the standard). Since there are so many different chainring bolts, and since I can only find three of the original, I have made some magnetic vinyl discs that can be glued onto the chainring bolts for sensor detection. The second head, I picked up some time ago. It has been modified (has a LBS sticker on the left meter but probably can be removed – see picture). The wiring inside does not match my unit (modified connection points) so this is more for display (unless you can reconfigure). One of the display windows is loose on the second unit as well. Now for the fun stuff: The Erisman Pacemeter used a Mallory 675 battery. Mallory is the predecessor to Duracell. This particular battery was a cardboard sleeve with 5 button cells stacked together. The major problem with these is they were of mercuric oxide construction (VERY BAD FOR THE ENVIRONMENT!!!) and are now banned. With some research, I was able to find a hearing aid battery that can be stacked to replace the original. I simply rolled them in blue Scotch paint tape and it worked on my unit (see picture of old battery). Included in the purchase is the following: 2 – display heads (see information above) 4 – sensor pickups 1 – fork MPH sensor bracket (excellent condition) 1 – fork MPH sensor bracket (broken – needs to be zip-tied onto fork) 2 – seat tube RPM sensor brackets 5 – loose MPH spoke magnets (3 required) 1 – New package of 3 MPH spoke magnets 3 – Original RPM sensor magnets 15 – RPM magnets discs for attachment to back of chainring bolts 2 – New battery sets (one in each unit) 6 – spare button batteries (make one more unit) 25’ – new speaker wire (to wire plugs to sensor – will require soldering iron used on electronics) 2 – new 1/8” mono plugs Also included: 2 – pieces of correspondence with Erisman 1 – A recollection story of a relative about the Erisman Pacemeter story. I do not have the instructions for the unit but will write something up to include with the purchase. Please let me know if you have any questions. Feel free to make an offer. All offers, unless ridiculous, will be given consideration. Shipping for purchase will be via USPS Priority Mail Positive feedback is very important to me and your satisfaction is of utmost importance. I will, of course, leave positive feedback after the completed transaction. I appreciate you visiting my sales page!