I have been given several old Garmin GPS devices. My cousin gave me his Edge 500 when he bought a Wahoo Elemnt Bolt, and
@Sharky was kind enough to donate an Edge 200. I am going to use the 500 to display speed/distance/time etc. and simultaneously use the 200 for navigation.
Using 2 GPS devices per bike means that I need 2 mounts per bike. I had a few lying around but needed more and was pretty shocked at how expensive they normally are. On Saturday afternoon though I spotted a bargain on Amazon. That mount was available for a bargain £1.79 with free overnight delivery on Prime. It is mounted to a 5 mm stem spacer. All of my bikes have at least one 5 mm spacer above the stem so that kind of mount would work well.
Unfortunately, only one mount was available at that price. I thought I would buy one, see how I got on, and watch out for others in the future if I liked it. (There are quite a few very similar but much more expensive mounts on Amazon. I assume that this one is a cheap copy, but it seems to be well-made, so no problem there.)
The mount arrived as promised, less than 24 hours after ordering it. It is well made, though its internal diameter is slightly big compared to the steerer I mounted it to. No matter though - it is held tightly in place by the cap on the headset. (I used the original spacer to adjust the stem against the headset bearings, and then swapped to the GPS mount spacer once the stem bolts had been tightened.)
If I can find these again at similar prices then I will buy another 2 or 3.
I assume that the second round part is for mounting other types of GPS - Wahoos, perhaps? I'm not sure what type of device the other piece is designed for?
Mount on bike, with my original 'out-front' mount on bars.
Edge 200 and Edge 500 devices fitted...
If the monsoon season ever passes here, then I will go out and test this setup!