Yes I have the same experience when training in erg mode. I can do the same workout on the flats and up alp du Zwift with very different results. Going up Alp the workout is much easier.
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I experience the exact same issues and itās extremely frustrating. ERG mode becomes significantly tougher going down hill. Itās as if Zwift tells my trainer to hit the ābrakesā as soon as it hits a negative gradient. The steeper the gradient the tougher it becomes. Similar when going up gradient it becomes slightly easier, but it feels like the biggest difference is when itās going down hill. I feel it just as easily when not looking at the screen. Iām on a Wahoo Kickr Core purchased in January 2021 and I use Zwift on my iPad. Itās ridiculous that such a big error can occur, especially when youāre paying a premium subscription fee and Iām seriously considering switching to another fitness app as ERG mode is by far my preferred training method.
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I did a workout on a hilly route (Out and back again) for the first time today and noticed it was harder going downhill than climbing, even when I closed my eyes, thinking maybe the effect was psychological. Googled it and came straight here. So evidently it is not my imagination!
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Welp, it seems this bug has still not been fixed. Did the FTP test and going over the 5.8 mile Epic KOM in Watopia I could clearly tell that downhills were about 5% to 10% harder. I couldnāt tell for sure but it seemed like it was more noticeable on the gradient change then on the entire ascent or descent.
LPT, always do FTP tests on a flat course.
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Paul i have this exact same issue, if i use zwift via bluetooth on the laptop the trainer almost works in reverse, (easier up hill and extremely hard downhill) i then used zwift on my samsung android phone and it works perfectly. i cant seem to work out why via the laptop it works so different, so ever since ive been using my phone, very annoying. not sure if there is a solution ?
This is still happening to me with a Wahoo kickr and running a computer as the head unit. Uphill is easier and downhill is harder.
Downgrading your Kickr firmware to 1.0.xx will probably fix this problem. There are several threads on this subject.
Did the Muir and the Mountain loop today. Did not put it in ERG mode, but for the first time, had the same issues as described in this thread. If I stopped pedaling, it did not death spiral, so it wasnāt in ERG mode. But I was in a much higher gear than I should have been going up, and it was notably more difficult going downhill. Has there been any update on this issue? Apple TV/Trax Neo 2T. Thank you.
This effect definitely happens also with kickr bike and ant+ connections with 40 minute steady 230w intervals in erg mode. Uphill easier effort than downhill or on the flat.
I know the interval didnāt change because I deliberately designed the workout to avoid that.
That shouldnāt occur, the effort level shouldnāt suddenly change in erg workouts, the terrain should make no difference.
Doing same workout in other software everything works correctly.
Just wanted to add my feedback so others donāt think they are imagining this.
If youāre using ERG, the wattage should stay constant regardless of your cadence or gearing. Thatās the whole point of ERG mode.
When you say itās harder or easier depending on up/down hill, what exactly is harder or easier?
For example, if you pedal a constant 90rpm at 200W (ERG), does the output wattage start increasing as you start up AdZ or Epic vs staying at 200W? If it stays at 200W while youāre at 90rpm, how is it harder? 200W is 200W. If you think Zwift is lying to you, then record independently to your Garmin, Wahoo, etcā¦
Iām really curious because I have never experienced this w/OG Neo and AppleTV.
Whatever it is, the Zwift erg mode is influenced by hills and descents. As soon as you hit any slight hill, the perceived effort reduces even though the cadence and power remains the same in the interval block. Then as soon as you go downhill, it increases.
This is definitely in ERG mode, Iām not stupid and I never use ADZ for workouts. Others recently also mentioned this effect again.
And itās why I always switch to my old PerfPRO Studio software for intervals in erg mode, it never does that - the effort remains level.
Iāve used Tacx NEO 1, Neo 2T and kickr Bike on Mac OS or Apple TV and with Bluetooth or ant+ connection.
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Yep, havenāt had a recurrence for a year but it most definitely is a thing when it shouldnāt be. I never changed my firmware as most of the time I addressed the issue mid-ride by resetting the kickr. I recall doing a blind test with my daughter keeping score. I was blindfolded and would say when I thought I was going up vs down. I was right 100% of the time. Wasnāt overly frustrating given the infrequency and my ability to address it with a reset most of the time. The odd occasion when a reset of the kickr didnāt work, a re-launch of zwift did.
I should add that request to Zwift support went unanswered, much like my 3 or 4 requests to correc t my age from 120 to something a bit more reasonable.
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I wasnāt replying to you directly nor implying you are stupid. Iāve used KickrV1 as well as NeoV1 w/out experiencing this on MacBooks, AppleTV, and iPhones.
I dual record to a Garmin. The cadence and power are constant on the Garmin which match that of Zwift. Hence, my confusion and my question, what exactly is harder or easier? 90rpm/200W on flat vs 90rpm/200W on AdZ is the same no? If the cadence and wattage donāt change, how does the effort get harder/easier?
Itās been a long while since I did ERG up Zwift, but Iāll do so this week to see if anything has changed.
Spiral of doom is part of the fun.
Whatās not fun on Zwift is how in ERG mode the effort seems to increase on downhill sections and is easier on uphill sections. So I try to find the flattest routes to get rid of that effect and keep the effort level for all of the interval blocks.
Iāve had that for a long time and donāt bother reporting it because there is no way to prove it without buying power meter pedals and everyone says almost the same thing from script so no point in going further.
if you enjoy that then you will also enjoy that iV doesnāt give you a tick for a completed interval is you use the bias to make it easier. Zwift does 
Are you sure thatās not your mind playing tricks on you in that it seems strange to push on a downhill especially when you seem to be going quickly?
Zwift doesnāt use the gradient for resistance in ERG mode, though it does for your speed.
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It is almost certainly this. It often happens as i go over the top of a hill and i expect it to get easier but it doesnāt so i kind of ease of the power in anticipation for the downhill that never comes!
Enough people do workouts up the alpe that people would definitely have noticed massive fluctuations in erg mode when going around the corners.
Exactly the comment I knew would be posted which is why I donāt bother.
Iām not that hopeless - and Iām going at a level that is not maximum so I can judge pretty accurately the force is higher on the downhill parts of a course.
Iāve seen others comment on the same effect before.
Perhaps a topic you even replied on previously might refresh your memory:
https://forums.zwift.com/t/easier-going-uphill-in-erg-mode-harder-downhill/14388/16k
Others: Zwift ERG Mode - hard to hold Watts on downhill?: Triathlon Forum: Slowtwitch Forums
so you think either your trainer isnāt reporting the correct power or zwift isnāt showing the correct power on downhills?
I have power meter pedals so could test it out. Having looked back over some past workouts I have done there is no change in power, cadence or heartrate on hills compared to flat sections of anything I have done.
Iām sure my kickr V5 changes depending on gradient when in Erg mode, I tend to notice it on the rolllers in titans grove and the esses