I have the GSC 10 and Cadence and Speed sensors working no problem!
The other posters clearly not reading what I'm saying. This works. It is easy. Set the Garmin computer to show you cadence and speed - match to ANT+ device connect - spin the back wheel - rotate pedal - watch display for readings. You can adjust until both display. I've been using this for a week now - and its working fine - and I hammer on my rides - 40mph top speed - rough roads - the works.
Because the wheel magnet is locked on to the nipple it is NOT flying anywhere.
There are NO wires to remove - the folding of the bike is NOT effected.
Note this is with 175 crank and 451 wheels - now for 170 cranks and 406 wheels - you may not have enough spread to play with - but you may - there is more tolerance than you think in the width that the GSC 10 will accept than Garmin's instructions make you think...