We ordered the casters for our bike box from grainger.com:

[TABLE="width: 586"]
[TR]
[TD]1[/TD]
[TD]Stem Caster Mounting Socket,PK5
Item no: 5VT35
P.O. Line #: 1
[/TD]
[TD]1[/TD]
[TD]Yes[/TD]
[TD][TABLE]
[TR]
[TD]$9.81 [/TD]
[/TR]
[/TABLE]
[/TD]
[TD]$9.81 [/TD]
[/TR]
[TR]
[TD="colspan: 6"][/TD]
[/TR]
[TR]
[TD="bgcolor: #666666, colspan: 6"][/TD]
[/TR]
[TR]
[TD="colspan: 6"][/TD]
[/TR]
[TR]
[TD]4[/TD]
[TD]Swivel Stem Caster,13/16"W,2"D
Item no: 4X948
P.O. Line #: 2
[/TD]
[TD]4[/TD]
[TD]Yes[/TD]
[TD][TABLE]
[TR]
[TD]$8.59 [/TD]
[/TR]
[/TABLE]
[/TD]
[TD]$34.36 [/TD]
[/TR]
[/TABLE]

You would use smaller, lighter ones for your project. I reamed out the holes in the mounts so that the casters were fairly easy to push in and pull out. There are a variety of styles of caster mounts besides the ones we used.

The more stories like yours I hear, the more I think that bikes and trains don't mix very well. I met a woman whose partner got on the train, but a train official said there was no more room and shoved her and her bike off the train. Her partner had the tent and all the money and credit cards. They didn't have cell phones. She did find him after searching for a couple of days. How's that for pure terror?

We bought a 4-band phone and a SIM before we left the States. Lucky that we did, because one of our flights was delayed over 24 hours.