tandem on train SE Asia

We are cycling through SE asia and china on our tandem. Our time is running out and we will have to take a train or even a plane for some sections.
Does anyone have any advice/experience of getting a bike (tandem or otherwise) on trains in Vietnam and/or China? we would probably try and travel from Hanoi to Lau Cai and then from Kunming or Chengdu to Beijing.
Thanks!!

There is no problem getting your bike on a train in Vietnam. Buy a goods ticket at station, then take the bike to the goods section at least half and hour before departure time (preferably a lot earlier than that).

There is no train between Lao Cai and Kunming. The bus station is in Hekou on the Chinese side of the border. When you leave the Chines customs and immigration building, go left then take the first turn right. It's only 200metres away.