Hey Guys
Amuro Ray is right when he says that the Birdy bag is only worn as a backpack when it's not carrying a bike, once un-zipped & unfolded (without having to empty contents of the rucksack BTW) it is then carried over the shoulder using the the long strap, the rucksack straps tuck away into a pocket.
I have used mine with my Birdy & Brompton as a way of picking someone up from the station, I isn't the most comfortable way to carry a bike so only ideal for a few miles.
I thought I had some pics of my bikes in the Birdy bag, will try to dig them out or take some new pics.
Safe riding! Chop!