The "captive" CA V3 magnet :-)

thingiverse

After nearly losing 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, whether they came with the CA V3 speed or were part of a bike computer, tend to get loose when used on an MTB. My design takes a different approach, using two zip-ties to mount the magnet to the spokes. While it's still possible for the magnet to get lost, this isn't very probable. I used small neodymium magnets from E-Bay with a diameter of 4 mm. To attach the magnets to the magnet holder, I simply glued them in place using Sikaflex, but epoxy or superglue would also work. Feel free to adjust the hole for the magnet in the OpenSCAD file if needed. Those neodymium magnets are much stronger than average CA magnets, allowing for a higher distance between the magnet and sensor.