ERG mode wattage incorrectly too easy?

I am just starting with Zwift and noticed this problem immediately (still on my trial). In erg mode I can hold much higher watts than non-erg mode. I took two 5 min segments in the same ride. It was a 2:15 ride and the two segments were 15 min apart (last “over” segment and first 5 min right after the 10min cooldown ended) so added fatigue shouldn’t be too much of a factor.

avg in erg - 171w 133hr 76 cadence

avg non erg - 154w 149hr 76 cadence

The non erg power output was of course spikier than in erg mode, but the difference is massive for that small amount of power fluctuation. 17w higher at 16hr lower just seems like something is wrong.

I manually raised my ftp from what my test scored me and still felt the workout was too easy (SST Med). After the workout ended I felt like I didn’t get a good workout so kept riding a while. I guess I could just crank my ftp up another 20-30w after every test if I can’t figure this out, but would prefer it to just be accurate from the start.

Edit: Forgot to mention the trainer I’m having this issue on is a Kickr Snap.

I’ve had 2 Kickr Snaps and power accuracy was a joke. You need to ensure that it is correctly calibrated with an Advanced Spindown and then do a regular spindown every ride after a short warm up to get the tyre and Snap up to normal operating temperature.

If you’re finding workouts too easy then it’s likely that your FTP test wasn’t done hard enough. Perhaps do it again. Note that not all workouts are meant to be hard. Some are pretty easy. They typically are a hard day followed by and easy day and then one or two days rest per week.

BTW you might want to try a higher cadence. 76 is really low. 85 - 90 is the normal range for most people.

Thanks for the reply. I’ve done an advanced spin down and have been doing a normal spin down every other ride. I will make sure to do it every ride and hope it helps.

My FTP test probably wasn’t done perfect since it was my first time doing an FTP test. The workout I was doing was a standalone workout for sweet spot training so it makes sense that if the FTP wasn’t accurate then there wouldn’t be a much challenge. The issue though is that if I had turned off ERG mode and manually got to the power levels then it would have been challenging. Hopefully more frequent spin downs will help with this.

As for the cadence I know its low. I have only been cycling a few months now and feel like I’m rocking a bit when I break into the 80+ range. I appreciate you pointing that out though and I am working on it.