Lot's of ANT+ and similar senders and receivers don't work well between the rear wheel and the handlebar. Distance is certainly part of it, line of sight could be too. Try it and find out is all you can do. You don't have to mount it, just mount the magnet on the rear wheel, hold the sensor near the rear wheel, and spin it. You will know pretty quickly if it works. You might want to look at RNAV's thread about his Trek built in rear-wheel sensor not working well with his Garmin: http://www.bikeforums.net/road-cycli...ep-inside.html. Even system made to work from the rear wheel often don't.