When I moved to California from the Netherlands, I was very excited that my Brompton fit in a giant suitcase that I already owned. (I decided against the cardboard box.)
The suitcase was convenient for moving purposes because I was shipping everything else via post or freight. For short business or pleasure trips, it's not realistic... It's too heavy and with only my bicycle inside, it weighs in just under the limit. No clothes and no bicycle accessories can be packed.
This led me to keep looking for an alternative. Lucky for me, this recent post from Urban Velo highlighted a bag designed for inflatable kayaks but useful for S&S coupler bicycles.
The bag is lightweight and almost the exact dimensions of a folded brompton!
Before a trip this month, I ordered one.
I added some cardboard to the edges for protection and to "hide" the bicycle from view through the mesh. (The ladies at the baggage counter told me that if they knew it was a bicycle, they'd have to charge me extra even though it's regular size luggage.)
The bag is really light and strong, and the bike fits very well inside with plenty of room for other things. My bicycle survived the round trip with only a slightly cracked front fender and I might have done that myself. Next time, I'll add some bubble wrap.
For just under the weight limit, I could put in the basket, a chain lock and some clothing as well!
The only problem was carrying the thing around the airport... I'm not putting 50lbs on my back but I could carry it small distances with one hand. Wheels would be nice.
Overall, it was a success and I'll use it again for my next trips!