i like complicated projects like that.
afaik, it will be your bike, used (even if you've only ridden 1km), so you can bring it back in your luggage w/o declaring it.
if the hotel is good, you can ship a parcel there, but if it becomes several parcels, and some are oversized, and they will have to sit on it for weeks, and so on, then make sure to call them and agree, as it really isn't their job.
Alternatively, i know a transporter in shanghai, he should still have 10 chains for me and a bunch of gizmos. he aggregated a dozen shipments for us last year and shipped us a few boxes. i can't say i like him, but he's not unreliable. information does get lost in translation, but if you get him to repeat things very specifically, you can assume he understood. he handled the move from china to europe of a friend, so he's a pro, he's not just some guy. but shanghai is big, so idk how convenient it'd be for you to use him. DM me if you want his details.