If anyone is interested in producing a kit or finished project to put for sale like this, I'm struggling through that right now and lightly blogging it. My first PCB prototypes just came in.

A good post to land on: http://projectexcitebike.blogspot.com/2010/01/how-to-build-y...

A kit seems hard because of all the different models of bikes out there, no? What other obstacles are you finding?

I love the idea BTW!

It will actually work on all the bikes I've seen, it just requires a flexible mount like double sticky tape vs something that clips or literally bolts on. I'm sure as I encounter more bikes I'll start to throw in little mounting tricks like Velcro straps or spacers.

Also I might have a way to simplify your idea.

Have the user keep an iPhone or Android phone in their pocket (or on a leg strap) and then sending the accelerometer data to the arduino (or switch from xbox to PC games and send the data over wifi or bluetooth)

Have you considered something like that?

That's a good idea - I've thought about putting smart phones on the ankle but not stopped to think that the pocket is sufficient.

Now, that said, it's hardly simple to get that signal off (via bluetooth I assume) across several platforms and read into a micro controller.

But I like that kind of problem more than I like the mechanical engineering and design issues of the sensor ring, so I'll definitely give it a closer look. Thanks!

How do the open source medical equiptment projects jibe with all of the FDA regulations?

I've always wanted to start an open source ultrasound project but I figured there would be too many hurdles.

Don't target medical markets. Target weld inspection.

Exactly. I work in medical hw/sw and I can tell you the amount of bureucracy is insane and everything is orders of magnitude harder than any non-regulated business. Open Source itself is not really a problem, we use a lot of it (os, libs, etc.).

But those projects listed OpenEEG, the one for anesthesia, etc are targeted as medical devices (I think). Are they just operating under the radar?

They are targeted towards hobbyists...