Finally, a intellectual perspective from gaoxing. There might be hope for you. Anyway, I would like to counter your viewpoints with some of mine in a respectable and objective manner.
I wouldn't go as far as saying that they are racist or prejudiced, but I would say that they are indeed ignorant and have not been exposed to too many "outside cultures". Racism is biased against someone solely based on their race. Chinese people for the most part are biased not because of race but because of misinformation fed to them or stereotypes associated with certain races. Subtle difference but an important one.
With regards to the biker, what exactly did he say? You believe he might have made a derogatory and racist comment, and I am not arguing he could not have, but unless you heard very succinctly what he said, you are only assuming and that would be hearsay.
And finally, the reason a Chinese person would be less likely to be stared at in the major international cities that you've mentioned is that there is a constant presence of Chinese people in those cities. People are used to it. How ever, it would be wrong to assume that minorities do that get harassed. There will always be jerks and racist roaming those streets and hence why the US enacted hate crime laws. Blacks have been present since the founding of the republic and yet they are still targeted in large cities like LA, NY, SF, DAL, BOS, etc.
The reason for the staring is that dark skinned foreigners are not common in the streets of Kunming, although more common than your personal experience would tell you. If you see a panda roaming Wenhua alley, would you casually walk by as if nothing's out of the ordinary, or would you be flipping out your camera phone and posting it on YouTube?
My point is proven by the very fact that you, as a foreigner, is some one I would assume have been accustomed to seeing African-[Insert Country Here] in the streets of your neighborhood, stopped none the less to observe this individual. Had it been an light skinned foreigner or a Caucasian, would you have stopped to observe? Is this some kind of double-standard or does that make you a racist as well?
In summary, I am not invalidating your observations of China because I do firmly believe that there ARE Chinese racist out there and that foreigners do get gawked at quite frequently, however, I do feel that you are making broad stroke arguments and making generalized assumptions. I do feel that there should be more dialogue between Chinese people and foreigners and not just dialogue between the governments. And I do encourage all of us to be patient and enlighten our friends on what our cultural values really are other than what is being spewed out by the CCP propaganda department.
Just a friendly brain dump on the issue.
Cheers~