Garmin Edge 500: broken tabs

As I rapidly descended Panoramic Highway toward Highway 1 from Mount Tamalpais with my Roaring Mouse teammates, I passed by some sticks on the side of the road. Suddenly something hit my foot. That didn't feel like a stick... I felt my pockets and nothing seemed loose, so perhaps it had been a stick after all.

Seconds later one of the riders behind me shouted "computer!" And then I knew. My Garmin had fallen. A quick look at my stem confirmed it: the bracket was empty, a white sliver of a plastic tab the only remaining sign of my Edge 500.

Fortunately after a bit of searching we were able to find and retrieve the computer. Honestly I was as worried about losing the ride's data as I was about the computer itself. A quick inspection showed the problem: the plastic tabs on the back had sheared off. Indeed one of the tabs had already come off during a previous ride. But the one remaining tab seemed enough to hold it in place. I'd taken to using a piece of rubber cut from an inner tube to secure it, but when that didn't seem necessary, I started just putting the computer in the mount as usual. The other tab had decided to give up the ghost during the descent.

Here's the back of the Edge, tabs gone:

The curious thing is I've had this happen to me before, not just once, but on two separate units. So this is the third. Additionally, I've heard of others having the same issue. It's clearly a design flaw: a lot of stress is placed on these plastic tabs, which extend outward at a right angle, and that creates a stress peak at the corner.

I've heard this is a particular problem with the K-Edge forward mounts, which are metal and harsher on the Garmin's plastic. I'm not sure if this is true; the stock plastic mount seems harsh enough.

Is there some aspect of my use pattern that makes me particularly prone to this failure? I don't know. I am glad I got this one back and the data were spared: it was an excellent ride and I'd hate to have lost it.