Derny racing is still a UCI event with the smaller 50cc Moped style Derny's with no roller and normal Track bikes, the riders sit in closer to the mudguard of the bike and call out the same, they reach about 50mph.

They are still exciting races and the tactics are the same. There is no speed restriction but restriction on the riders maximum gear for the event 102" I think but don't quote me. The UCI tech regs has a full section including design of the bikes.

The style of event pictured is the type Eddy Merckx broke his back in before winning another four tours, now thats a comeback.