I am not sure whether this is helpful to you, but the Chinese postal service is quite ok. If you have an adress that you can send the bike to, sending it in advance would be an option. Postage fee is not expensive. China Railways Goods Services (中铁快运) seems to be an option and according to their website they are very quick. Should not take more than four days on any given route inside China.
Whether all this is possible for you would depend on whether they have someone who speaks English good enough at the office in Lanzhou. Or you could find someone from the hotel or just any English-speaking university student to help you. Of course you should pay them for their efforts, but it would be relatively inexpensive to you and a nice bit of extra money for them.