Garmin + Wahoo Kickr: Setting a Grade works, but Watts doesn't...

[Manc33]

I'm using a Garmin Edge 1030 Plus and Wahoo Kickr.

If I put the Garmin on the Indoor profile and swipe down, I can set Power in Watts, or a hill Grade %.

Using it to set a grade works fine, I can set it on 9% or 10% and use the lowest gear on the bike (22t chainring and 32t cassette) and after around 5-10 seconds of easy pedaling, the resistance kicks in and it stays that way.

If I set the Power at 135 Watts, it starts resisting after 5-10 seconds as usual, but then it suddenly goes way too easy to pedal, then it resists like it should, then goes easy again. This is again using that really low gear 22t x 32t.

Is it because the gear is so low? The speed is too low? I'm doing about 3 MPH but, Grade works fine at that speed.

If that's the case why would "Grade" work, but using a Wattage target doesn't?

I have yet to set it at a lower Watts (like 100W) and using a higher gear, thus going faster. If that works then I guess it just doesn't work at such a low speed. It's swings and roundabouts really, I can just set the Grade but being able to use a set Wattage would be better.

[Manc33]

Bueller? What if I just use a higher gear?

The Watts set on the Garmin/Wahoo Kickr should give me the same resistance, regardless of the gear, but in higher gears the pedaling will be slower?

It that what's going on?

Tonight I made a "Test" workout on the Garmin, fluctuating once every minute between 80W for 1 min and 100W for 1 min (3x) so it was a 6 minute test ride... I tried it for about 4 mins and it worked OK on the middle chainring and middle of the cassette. There was no slackening off of the pedals like I had in the lowest gear (22 x 32) as explained in the first post.

Tonight I tried to make a Workout on the Garmin and that's the Test workout I mentioned above. It worked OK. That's just a test though, and a far cry from making it 135W or, as I discovered 194W for 10m 50s that I want to make it.