Anonymous, they have been a variety of bikes priced from 100 yuan to 3000 yuan. They've always been locked to a tree or post through the frame. One was stolen while I ate in a restaurant. Two were stolen from officially guarded parking areas.
If you have a good bike here I would suggest you cover up brand stickers, tie some old rags around parts of the frame, don't clean it and always take it into your apartment over night.
The bike thievery in this city is out of control! I have lost 8 bicycles in four years. A friend has lost 7 e-bikes over 3 years. It doesn't seem to matter where you park it, 'official or not'. People offer to sell 'presumably' stolen bikes near the north railway station when you ride past. However I think most of the rampant bike stealing fuels a large operation that sends bikes to other provinces. I would just like to warn people intending on moving to Kunming and buying a bike. Take it into your apartment. Take into your workplace. Don't leave it for more than an hour outside anywhere.