Can anyone give me a sense of the cost to mail a large package (books, clothes or a bicycle) from China to the U.S.? Time to delivery isn't really important .

Price varies - if you use the post office (international post office on beijing lu) prices start from ¥100 and go up depending on the height, size, etc. You can send via sea (about 3-5 days - guess those boats really cook these days) which is cheapest.

You should EXPECT your box(es) to be beaten to a pulp on the Chinese side - and probably on the US side also - so pack it well and bubble wrap EVERYTHING - even books - use the small bubble wrap on the inside and the BIG (1-2cm) bubble wrap on the outside...and sorry - don't know where to find the bubble wrap. I remember Metro USED to have it in various sizes - but it's been a few years since I looked. You can also look for bubble wrap on taobao.com - I'd almost guarantee they have it...