After nearly having lost the screw-on magnets for my two Cycle Analyst V3 speed I decided to design something more "captive"...or "undetachable" (so to say).

Most screw-on magnets I found (be it delivered with CA V3 speed or simply a bike computer) really have a tendency to get loose if you use them on an MTB. My design is a bit different as it uses two zip-ties to mount the magnet to the spokes. While it still is not impossible that the magnet gets lost, it is not very probable :-)

I used small neodymium magnets from E-Bay with a diameter from 4 mm. I simply used Sikaflex to glue the magnets to the magnet holder but I guess epoxy or superglue will do as well. Feel free to adjust the hole for the magnet in the OpenSCAD file if needed.

Those neodymium magnets are much stronger than the average CA magnet and this simply means that the distance can be quite high.