Hi Stuart
conditions on the day dictate average speeds so you cant compare one rider with another or bike with another unless they are out at the same time and close to each other ... the weather can change very rapidly in different parts of the island which impacts different competitors at different times ..
in practice last year 105MPH average for one lap and 148MPH through Sulby but ran out of gearing ...
this year because we started behind the 500 singles which are mostly a lot slower and became an issue getting past , the weather and track conditions were awful we went 138MPH through sulby and just under 101 average was the quickest lap ..
HTH
steve