Steve, corect no one could do 34 mile in 3.5 hrs. Thats not what matters. Its total kcals burned. If you decide to walk 34 miles it will take 8.5 hrs (at 4mph) and 3400 kcals ( ~7kcals/min). If you run at twice the speed (8mph) it will take half as long but your kcals/min will double (4hr15min at 14 kcals/min). Its still the same amount of work performed-3400 kcals. So, if you COULD run 34 miles in 3.5 hrs it would still be 3400 kcals, only the kcals/min would change. Bototm line- for someone to ride 60 miles and burn 3400 kcals in 3.5 hrs ( 14 kcals/min) is very reasonable. ( FYI- my prevoius post this AM was in response to Danno and CbCf. I'm new to this forum and not used to how you would reply directly to someone else.)