So… I did a ZRL TTT this eve with the Trainer Difficulty at about 10%, maybe less. The good news is it was way better. There was only 1 hill, not too steep, but it was much easier to stay with the pack. So I’ll need to try it out on a steeper section. That said, my instincts and experience tells me that a larger freewheel requires a bigger hump to get over to maintain momentum when resistance hits (similar to co-efficient of dynamic friction for any physics students - surely 10% resistance applied to a 10kg weight requires more instant power to keep momentum than a 5kg. Yes the power required translates to movement on screen but I think I also burn a match in the process… Any mechanical engineers out there?