*** of the North Stage 1 - road feel

I was riding "*** of the North Stage 1 - Wallers Arenberg" on my Tacx Neo Bike; when coming to the cobblestone-streets, I had to work much harder, needed to go back into first gear, but the speed didn´t decrease - what means : first gear, 71revs, 35 km/h.


the bike has the last firmware-update and no problems on paved roads.
I tried the same ride with a Tacx Neo 2T, no problem there ..