My Race Prediction on the Garmin 955 is way worse than the one on the Garmin 245. I've run a 10k in super bad conditions while still finishing 36:51, while the race prediction showed my something like 38:30. I noticed that the prediction went up as I started to do more trail running and to run/hike more climbs during my runs. May that be the cause why the predictions are so off? I've heard that trail runs don't count towards the VO2Max value anymore.