Strava

That worked a treat, thanks. That's cut the amount of nonsense commuting rides in my feed by 50%.

http://app.strava.com/rides/11409946

I tried as well, but there's that huge flat non-sense right in the middle of the data in the performance tab that makes the visualisation useless to say the least, you know... those crappy 9 hours when you stay off the bike...

Plus the difference in elevation once the device is turned on again...

I think I'll stick to the 2 recordings per day, sadly.