Motivation Ever since I took control of my own running data, I’ve been gradually adding features to reduce my reliance on Strava/Garmin’s analytics and have it all custom instead for my training purposes. One bit of analysis I’ve always wanted to do is model my fitness with the objective of providing accurate race time predictions (or at least more accurate than Garmin’s which I’m wildly sceptical of - I’ve no idea how accurate Strava’s are as I don’t pay for premium).