A few of us are heading over to Italy by train next month to do the 24h of Finale. In order to take your bikes on most European trains they have to be bagged - the problem is that your average bike bag (I have a Neil Pryde one) isn't very portable, even without the bike in it.
We're wondering whether the best solution is to get a cheap thin bike bag (maybe giving it shape with some cardboard that can easily be ditched) like this:
http://www.chainreactioncycles.com/Models.aspx?ModelID=41796
Or I saw a link somewhere to a guide to making your own bike bag, but can't remember where, and don't know where to purchase the materials.
Any help would be much appreciated, because this is seriously denting my bubble of smugness from deciding not to fly!

