Bike polo is quickly becoming popular. A group of guys armed with golf clubs, or the big plasitc whiffle ball bat will do. Crocet mallets or any home made version. There are also, offical bike polo mallets.
About a 4" ball works well. I found some at the discount store. There is also, an offical bike polo ball.
Search bike polo on line for more info and rules. I have found that just playing the game is the best, NO rules, golf clubs work good. Hit the ball til you make the goal. !! Play hard, Ride hard, Have a good time(no pun)
We play in the city park. I have noticed other fields since, as places to play.