One of the fascinating things about having a world where you have radically different sizes of intelligent species is that all kinds of different sport and entertainment events become possible that don't exist here. An example would be indoor mouse velodrome racing for riders who are only about 8.5" tall.
Imagine a fixture looking like a giant crap table about twenty feet long; around the edge is sloped reinforced glass that keeps spectators from throwing things on the track or reaching in. The track is a steeply banked oval, about 25 to 30 degrees, and is made of wood. There is a lift area in the center of the fixture from which the riders come up on to the track. When the race was over the mice riders would exit the same way. Located around the outside of the track would be seating for bigums. Mice have there own area built into the track to watch from behind glass. Over the tracks in would be large signs showing the start times and riders names along with betting odds. In modern day venues big screen TV's would also allow people who could not get a track side seat watch the race and place bets. Races would run for a set number of laps.
Since the main point of the racing would be to bet on the riders; efforts would be made to make the event free of tampering and fixing. Riders would not own their own bikes. All bikes would be pulled from a common pool via lottery five minutes before the race. Upon getting their bikes the riders would clip their rider number on to the back and would snap their number wheel covers on to the front wheel. Due to their amazing strength to size, the bikes are belt not chain driven, and have solid, but still spongy, rubber tires. Races are fast, aggressive and very demanding on the riders.