Luggage consigment for a bicycle on the k23 from beijing to Ulan Bator

Hello, I'm planning on checking in a bicycle on the k23 to Ulan Bator. Where at the station do I drop it off on the day before the trip. Is it at the Left Luggage Service counter?

Also do you think it would be better if the bike is packed up into a bicycle box or is it better being assembled as a bike to go on the train?

Thanks for your help