According to Official Guinness Records,
Sam Wakeling (UK) covered 169.90 km (105.57 miles) on a unicycle without his feet touching the ground on 29 September 2007 in Aberystwyth, Wales, UK. Mr. Wakeling achieved this record whilst completing the record for the longest distance convered on a unicycle in 24 hours.
For a complete list of 2007 records, please visit 2007 Guinness Records in United Kingdom.