zef eisenberg (born march 1973) is founder of sports nutrition brand maximuscle and an ultra-speed motorbike racer. he holds numerous land speed records for motorbike racing. his success in land speed racing has led him to become a tv presenter racer with the new tv series called speed freaks, a six episode production on itv4 , produced by keshet. he has also appeared on several other tv shows, most notably the bike show with henry cole with zef's famous madmax turbine bike. eisenberg best known for his motorbike exploits is a self-proclaimed ‘speed freak’ and no stranger to speed, he currently holds over 50 british and world land speed records including a prestigious guinness world record. his records include the world's fastest turbine bike (234mph), the uk's fastest (no-fairing) 'naked' bike (225.6mph), world’s fastest motorbike racer on sand ever at 201.5mph to britain’s fastest-ever motorcycle crash at over 230mph. fastest ever wheel powered vehicle in a 1500hp porsche at pendine sands @ 210.33mph and fastest electric motorbike in the world (unfaired) with a 197mph gps peak speed.