Big in europe (especially poland) I used to train with a club but never raced properly (just with other club members). Good laugh and fun for a summers evening, couldn’t really commit to regular race meets due to work, small club meant I got a bit bored of racing the same people week in week out and when the season ended I never went back.
Essentially you ride a steep angled mountain bike or road bike frame with moustache type bars, single speed free wheel and no brakes. CX tyres are popular.
Starting together on the line, you all sprint for the first corner. some try to keep it tight, some go for the midline and drift the back wheel out, I liked to go wide and sprint through the corners to keep the speed up.
4 laps and its all over. Crashes are common and contact is tolerated (within reason) wear long sleeves and gloves as the shingle will tattoo if it gets into an abrasion.