So you're biking or running along when the SLOWEST song starts playing on Spotify. Then you have to stop, change songs, and get back into your rhythm until it happens again.
With the BPMBiker, your GPS and speed are automatically logged with the LinkedItOne and uploaded to an Azure Mobile Service where they are stored in a database. An Azure WebJob there can check your average speed for the last few seconds of each song and then launch a Spotify playlist with the appropriate beats per minute for your pace. (WebJob to launch playlist still under development)