The Coast Starlight has a baggage car (I've taken it from LA to Oakland). Remember if you box the bike you can only get it at stations that offer baggage service. Check the Amtrak schedule for the train you want to catch to see which stations offer baggage service. Amtrak will provide the tape to close up the box. (The folks at the baggage center in LA are pretty nice. If you box it up in LA you need to go to their baggage office which is upstairs. Take the elevator in the alcove next to the car rental desk to the second floor. Go to the baggage office and ring the bell to be let in.) Amtrak charges $15 for the box and $5 shipping for a total of $20. You can get insurance if you want up to $2500.