this might be of use to any other geeks that keep a race record in excel.
=ROUND(1-(A1-B1)/(B1),2)*100
cell A1 is your time. cell B1 is the winning time. It works if you have converted to seconds already or if you format the cells to TIME
in other news regarding LDWAs being soft. after applying the formula to last years results an LDWA event (rombalds) yielded my worst score of the year and by a fairly large margin!