I use a Brompton (in conjunction with a train journey) to commute to the office. So far I have used my normal rucksack/backpack to hold my computer, notebook and other bits and pieces for work. However, I would much prefer to use a front-carrier bag on my bike instead of a back pack as doing this is much more comfortable. Also, not using a back pack whilst cycling means that I can dress more appropriately for the office (shirt, jacket, back pack whilst cycling is not a good mix). The thing is, on the days when I am not in the office, I am generally travelling on business - often by plane abroad. What I am therefore looking for is a front-carrier bag which I can use on the Brompton but which can also be comfortably used when flying, visiting customers etc. I really don't want to be changing bags all the time. The Brompton O Bag, looks good but it looks like it would not be very comfortable for flying around the world on business. I am also thinking about the Brompton S Bag or Brompton C Bag. Does anyone else have this kind of situation and have you found a good working solution? I would imagine that something with a capacity of around 20 to 25 litres would work just fine.