According to Jennifer 8. Lee, the best bagels in Beijing (known as "beigu" or precious wheat) are at Mr. Shanen's Bagels, a shop opened by Lejen Chen, a woman in her late forties who grew up in Bay Ridge, Brooklyn. Ms. Chen makes 26 kinds including ham and cheddar, which are neither traditional nor kosher. No word on whether she makes decidedly non-kosher varieties like Peking Duck or twice-cooked pork bagels, which both sound good to me.
One bagel not in Beijing: poppy seed, because of the association with opium. Some other delicious tidbits from the story:
When you google bagel in China, it's defined as a doughnut-shaped Jewish bread.
Chinese workers in Beijing will buy a bagel, cut it up in noodle-sized strips, and stir-fry them with bean sprouts and/or cabbage. I think some bacon would add immeasurably to a plate of stir-fried bagels.