I played some Bike Polo with the Beijing team. They were a great group of people, and even took me out for dinner afterward. Featured here is Julian, he has a customized bike just for this game. It has both breaks attached to the left handlebar to easy turning and swinging at the same time. The right handlebar is shortened to almost nothing. Also barely visible are white spoke gaurds to prevent the spoke from being banged up by the ball or a crash with another player. I crashed twice while playing Bike Polo and was kind of afraid to keep at it with my nice touring bike. I'd have no qualms riding my fixie into this game back in Shanghai. I'd switch the bike to a free wheel though. Its a lot easier to play with a free wheel than fixed. Peddling and shooting at the same time is really hard. I do think goal keepers could do well fixed so they can move backward and forward near the goal.
This group is organized by Natooke which also helped me with a rear tire. Friendly people, great service, Beautiful looking bikes. They do a lot to encourage cycling in Beijing. Major props to Tom who helped out but didn't play himself, he was a great teacher.