The idea isn't new, an airbag jacket has already been developed. Works with a cord, if you get separated from your bike then it deploys. There is a video of a man that survived a wreck due to this jacket.

here:
http://www.youtube.com/watch?v=TX_YIr5CkDM

survivor story
http://www.youtube.com/watch?v=uoGDwBiTYdU&feature=related

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