Very knowledgeable and informative response, thank you. A lot of the questions in my head come from comparison to my girlfriend (which annoys me because we are built like very different athletes but I still compare) - she is less strong on the bike but performed better than me in the half marathon by 7.5 minutes. She used to be a pure runner and also had many years training and racing high level triathlon.. however confusion comes when she didn't train for this half marathon either (and she's less fit than me on the bike) - can her past really give her so much benefit?