Bought the Garmin Speed/Cadence sensor but have problems with the pedal sensor activating the unit. Crank arm (Campy Record) is too far away to come within the 5mm needed for it to work. My frame 2006 Orbea Orca chainstays are too far away at even the closest. Any mods? I thought about getting a round magnet long enough to activate the sensing unit by attaching it to the spindle of my pedal. Otherwises, I can't figure this one out.

Pics would help.

You can rotate the cadence part and the speed arm independently. Rotate the cadence portion outward enough to get your 5mm, the loosen the screw on the speed arm, and swing it inwards so you pick up a signal from the rear wheel.