Here’s some old threads for bike rental and bike shops
@LukeForward might have something in his workshop over near Gong Guan.
Lots of FB groups for used bikes. You can also check FB marketplace. If that doesn’t work, you can always put up a wanted ad. You can also hit up the local bike shops and see if they have customer’s bikes on sale. Sometimes they sell bikes in the shop for their loyal customers.
Last thing, if you’re near 190cm and a big budget, I may have something for you.