I'm in the process of building aluminum cases for two Zizzo folders my gf and I just bought. I'm keeping them under the size limit to be safe, but because they also convert into trailers (to haul carry-on) and are relatively beefy, I'm bumping up against the 50 lb weight limit for economy seats. Right now I'm scratching my head as to how to incorporate casters and center stands with only 1 lb left to play with. :|
I have a folding portage cart with light weight removable wheels that attach via pushpin axles into metal receivers. Buy two extra receivers, drill holes in the side of the case, bolt on the receivers, and attach the wheels at the destination.
I haven't used it for this yet but plan was I would just take the wheels in my carry on. I also have not work out how to attach the cart to the bike yet.
Wike sells the individual wheels, pins, receivers (2) and even a diy box trailer kit(1) using these parts with instructions if looking to visualize this.
(1) https://wicycle.com/products/bike-trailers/diy2 (2) https://wicycle.com/support/replacementparts
Good on you for doing 70km! That's about the limit of my comfortable endurance on it too. My record is~100km plus two ferry rides touring on the west coast but I admittedly walked it up the last two hills in the dark and I started to wish I was done around 85km.
What do you use for checked airline travel? I have the B&W hard case but haven't tried anything else. I think it is a linear inch or two over regulation if measured but nobody has ever stopped me or charged overage.