According to Official Guinness Records,
Sem Abrahams (USA) rode a 35 m (114.8 ft) tall unicycle for a distance of 8.5 m (28 ft) at the Silverdome in Pontiac, Michigan, USA, on 29 January 2004.
For a complete list of 2004 records, please visit 2004 Guinness Records in United States.