Just reviving this thread to let folks know there is still interest! Critical Speed is really bad at predictions if you have faster times in shorter distances. For example I’ve run a 5k at 6:03 pace, and because my 2mi record was also set during that run at ~6:01 pace, CS R2=0.9999 thinks I can run a half marathon at 6:06 pace, whereas Vdot would predict 6:35 pace which is obviously more reasonable.