From too easy to barely maintaining 75 rpm while riding on 0% (or even -1%) while power and HR is way up... What's going on?

Hi all - so I posted before saying the effort level was too light the first month or so of using Zwift (using Tacx Vortex Smart). I made sure the difficulty setting was set to 80-100%, made sure tire pressure was 110psi, calibrated it, and it got a lot better. Then I took the ramp test. I was judged to be at 195w, which is pretty close to what I got in another app at 200w. Cool.

But since then riding even on flat or slight decline is taking a lot more work that it doesn’t feel realistic. I’m barely able to crank out 75rpm going on the desert flats or even slight declines. Bike says I’m going 22mph, but my power is closer to 170-180w range and my HR is up to 150-160. I can’t possibly be working this hard just going on a flat route. I mean it’s Zone 4 approaching Zone 5 HR for me and my power is almost 90% of my FTP? I can’t sustain that level of effort for too long.

What am I doing wrong here?

while you can calibrate the Tacx via Zwift, for my Kickr i sometimes calibrate it on the wahoo app, and also you need to ensure the tacx firmware is updated via its app too

I don’t understand your point. It’s very possible to work very hard riding on a flat route.

This probably isn’t what you mean, but it sounds like you just need to shift to a lower gear so that you can pedal at a higher cadence at a lower power.

I agree with what Steve said, try shifting down for a higher cadence. While it won’t change how much you can produce it might change your perception of how hard you work because you are more comfortable at a higher cadence. Pushing 180W to maintain 22mph (35kph) on a flat does not seem that unrealistic. Remember that weight also plays a part in this equation so maybe check that this is correct.

Ok I’ll try that. I haven’t been changing gears while riding Zwift since I figured the ERG would be changing resistance to appropriate levels so I kept my gears at what I would be using when riding on flat outdoors which is on big ring.

I was just riding at the same gears before doing the ftp test and it wasn’t nearly as hard, hence my statement. I average 90 rpm outdoors and the speed is about 18-20 mph or so when going on flat which was being reflected in Zwift so I thought previous setting was reflective of riding outside and was happy with that. Now it’s way too hard and I don’t think going down to 65 rpm seems realistic? I’ll try shifting down though but I typically have not had to change gears when riding indoors.

Both firmware is up to date and I always calibrate using Tacx app since I can’t calibrate or spin down through Zwift on my trainer.

This is true for workout mode, are you having this issue in workout mode or free ride. There is no option for ERG in free ride.

If your FTP goes up then the workouts also get harder. The workout levels is based on a persentage of your FTP.

I actually paid some attention on my ride last night and 170 to maintain 32kph on a flat is not unrealistic at all. One thing you must keep in mind also is that the road surface plays a big part too. I know that zwift have done some enhancements to this lately and the different in effort to maintain the same speed is quite different as you move to different road surfaces. I saw a difference of as much as 15w going from tarmac to gravel and noticed that there seems to be different levels of tarmac now as well. What is you w/kg when you produce 170w?

170w is about 2.42w/kg for me

I just checked your last workout, your screenshot show 21mph (33.6km/h) @ 162w. That is in the same ballpark as my ride on a flat road.