I'm starting in Seattle on Sunday for a cross-country ride that will end in Boston. I live in Palo Alto, CA.
In a normal year, I would just ship the bike via Amtrak Package Express. They were charging $85 to ship the bike +$15 for the box. You can easily pack it at any train station that handles check baggage, then pick it up at any other Amtrak station that handles checked luggage. Their box is big enough that all you need to do is take the pedals off, turn the handle bars down, roll the bike into the box, Tape it shut, and write your name and phone # on the box. Then pick it up a couple of days later at a station near your start point.
The bad news this year is that Amtrak's website says: "Amtrak Express shipping is suspended until further notice."
so that's out.
I considered just having a bike shop pack my bike and send as checked baggage, but I'm concerned that because I'm starting on Memorial Day weekend, I won't be able to get it assembled on the other end. While I have assembled bikes when returning from a trip, I'm concerned about not being able to do it with the limited tool set I carry on the road...
My flight is on Alaska. They charge only $30 for a standard (small) bike box, which will transport a disassembled bike. For $100 you can check "oversized" which can be up to 115 linear inches.
So, this year I bought an Amtrak box, which measures 41x70x9 = 120 linear inches. If I take off the front wheel, I can then carve about 8" off the length of the box, and therefore meet the 115 limit. Boxcutter and tape. Wish me luck!
I'm a hotel and credit card cyclist, so beyond the checked box, I only have 2 panniers which can be carried on.
I'm hoping that by late July, when I'm ready to return from Boston, Amtrak package express will be up and running again and I can just ride the thing into South Station, put it in the box, fly home, and pick it up a few days later at the Amtrak station that's a 20 minute commuter train ride from my house.