Originally Posted by
prathmann
Don't know of any current bike speedometers that use a Hall effect sensor, but Avocet made some that did back in the '80s. I still have one of theirs which uses a little ring mounted on the spokes at the hub instead of the single magnet used by the reed-switch models. One advantage of the Avocet approach was that it got multiple readings per wheel revolution and therefore a bit faster response at slow speeds.
The little Avocet pickups that worked with the ring magnets were just coils of wire. They were nice, simple, and somewhat robust (the connectors that slid onto the pickup's pins were not all that reliable). I'm still using these Avocets on three vintage bikes, and have a new Avocet 20 in the box. Very minimal, and a bit of a conversation piece.
These old Avocets do go through batteries quickly... mine last about a year. Maybe that's why there was an assumption that it used hall cells?
Steve in Peoria