UPDATE: made SCAD parametric, moved to 8mm magnet, flipped screw around so if you use a longer screw, it sticks out to the inside instead of to the outside.Glue in a small, strong magnet, snap it over a spoke and use 3mm screw and nut to secure it.It's best to mount it opposite the valve stem, and the closer you get the magnet and sensor to the hub, the more reliable your readings will be. The separation between the magnet and sensor should be around 1mm or so (fairly close).