VDO Cyclecomputing M5 Notice D'utilisation Abrégée page 55

Pairing the transmitters
ATTENTION:
when using the transmitter for the first time, the bike
recognition switch must be set to either BIKE 1 or BIKE 2.
Only then will the automatic bike recognition work.
PRESS and HOLD the button until the LED flashes.
Green LED flashes once = bike 1 is selected
Red LED flashes twice = bike 2 is selected
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