I think i prefer medium or below. When i have the hardest setting i feel like I have to change gear all the time and sometimes the hills just hit u like a wall if your not ready/prepared for it and lose momentum. What do u prefere and whats the best setting to do well in races?!?
I understand the hardest one can be nice if u wanna try a realistic alp d zwift or some famous climbing but i races I dont know…
I usually use a low setting in races to minimize the mental effort of paying close attention to shifting. I sometimes spin a little faster on the short climbs to stay with the group, while everyone else is dropping their cadence. Seems to work for me.
It depends of the elevation profile of the course, your bike and your trainer.
For flat courses, low trainer difficulty like 30% is best for me.
For hilly rolling courses, 60% to feel the road going up and put more watts like the rest of the bunch
For mountain courses 50% minimizes the gear changes.
The bike : if you have a small cassette like 11-28, low trainer difficulty like 30% is best to avoid using the front derailleur. I used a single ring with 11-36 cassette, I had to use low trainer difficulty. With my 11s 52-36 11-34 bike any difficulty was ok. Now I have a Neo bike set on double 52/36 11-34 12s (I used the ultegra cassette as my model), and 100% is nice as I have lots of different speeds.
The trainer : with the kickr core I liked low difficulty (30%) whereas the Neo bike shines on high difficulty… even 100% in race.
So it depends of so many things, you have to try and try again!