I have bought a pair of Bike Travel Bags (the black soft shell bags shown here: http://www.cdisports.com/index.php?c...index&cPath=98) last Summer for flying across the country (total 3 segments per bike, two bikes).

We got better at dismantling the bike for shipping and filling the bag after the first time.

Everyone I have spoken with whose work involve dealing with passenger bags at airports told me that cardboard boxes were the worst options, and that a clear plastic bag was possibly the best option. Why? Cardboard boxes look like you can pile them up, which is not true, they're not resistant enough. Bikes in clear plastic bags are impossible to pile up, and therefore will definitely end up in a safer place.

I could never convince my DP of that so we got the soft bags. I was not going to get the hard shell ones which I find too inconvenient, especially if you're like me a small person who will be travelling without a car. (And even then: it's not so easy to fit in a small car!!) The soft shell can be rolled away, taking less space, and is definitely less bulky. It's also going to sit on top of things in the cargo space of the plane. Or so do I hope... (I have watched the airport employees put our bikes on the plane while standing in the waiting area, and they seemed more careful than I expected.)

So they were quite expensive, and a disappointing value for the price: there are not enough handles on the model we got, but the padding is good. (Although of course we added our own padding, and undid many more parts than they suggest on the web site.) But they did the job fine, and the bikes were totally unharmed...

YMMV.