I like the first one with the front and rear lens, but it didn't mention the resolution quality. Is the camera installed on the rider's helmet or on the bike? How long does the battery last, or do you run it off a bike's cell phone charger (if it has one)?
The second one is more expensive, but it mentions the resolution quality. The down side is it is designed to face forward when you need to cover your front and rear views (for rear endings and side hits from cars changing lanes). I think you'll be better covered with the camera on the first link.
- Wolf