> - If you go with the coil option, you need an amplifier that will
> take the pulse from the coil and get it up to 5 volts

That does depend on the strength of the magnet, the speed and
proximity it passes by, and the coil winding

A PIC's comparator will wake it from sleep so amplification is
not necesselery needed. A good healthy pulse may actually have
to be clamped

As for the reed switch, if you took the conservative lifetime of
1,000,000 operations, for a 26" wheel, that implies a distance
of

(26 * pi * 1,000,000) = 81,681,409" => / 63360 =  1289 miles

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