I have been training for vEveresting for the past 6 weeks with a training plan and all of the workouts have been led by the ERG mode. Recently, I got a Zwift setup (basic Zwift trainer) and the virtual shifting click (Zwift Hub One). I used it a little bit before the training program, and never had any problems with it. It only occurred to me during this week’s long ride when I got on Alpe du Zwift that it would start malfunctioning at the higher gradients. I barely got into the steep section of the first bend when the resistance in the trainer (at this point I am in gears 2 or 3 and 10% gradient) would instantaneously go up to around 250 (my FTP is around 200) and then it would just as soon drop to about 120 or lower, alternating between the two at regular intervals. Obviously this is a big problem, and was wondering if anybody knew anything about this.
A couple notes was that when I got into the higher gears 5+, I didn’t notice this problem at all. Likewise, on flat ground I didn’t notice it either, even when I was in gear 1 (possibly due to the fact that there was little to no resistance at that point due to the low gradient). We checked the bluetooth, ANT+, Zwift Companion (along with making sure all the equipment was the right updates and such).
EDIT: After some more testing and switching the virtual shifting out for a cassette, it seems that the problem lies within the resistance (and thereby the trainer) itself (as in it was still happening at lower gears)! I had someone else try it out as well, and they confirmed my results. As described above, it was an on/off resistance.