Vibration in the pedals when in under load?

I'll try a new chain, to begin with - just to be sure and at the same time trying to keep risky expenses low... :-)

I have a similar experience; it does feel like magnets catching on. But when I hear people talking about a ‘buttery smooth’ ride, that is not how I would describe it. 

The thing that bothers me is if I dont know if it is normal or it has something to do with my tacx being faulty. 

Hi, did you manage to get this issue sorted out? I have exactly the same issue on a new unit with same cassette. I sent the video to Garmin and they are sending me an extra O-ring but it does not feel the type of noise an extra O-ring will address. Also, I have to wait 5 weeks for them to send a disc extractor tool since it seems Out of stock pretty much everywhere...

Unfortunately no - Garmin support is really NOT helpful, they asked me to send videos which I did. Videos are too large to attach to an email, so I sent them a link to a OneDrive cloud folder which they denied due to 'security concerns'. Ridiculous! I urged them to find a way, it seems like a 'try to play it back to customer, stress patience, see if they give up' routine - really disappointing and upsetting at the same time :-( 

I have changed chain, front chainrings, cassette is new. Tried to adjust derailleur, B-screw and everything. I am now 100% sure it is s/t related to the trainer. Seems it needs certain chain pull/tension and specific rpm range, thus seems a sort of resonance of the magnets being part of the electro-magnetic brake system. Didn't have it with the DiretoXR, though which is a direct drive as well. MAybe I should sell the trainer again, there doesn't seem to be any interest in supporting users at Garmin. Very sad... :-(

Hi, Sorry but I try everything , and I try to forget it and not using smallest cog ring ( highest rear cassette speed )  Garmin send me a new FreeHub, but my freehub is already new , my neo2t is brand new.   And i don't think that the vibration will break something, it'just very anoying.   

If the vibration changes based on gear, I would lean towards a drivetrain issue. Are you using a 10spd? are any of the cogs loose? or does the chain look like it is hopping a little?

My issue is a non-issue, I am 90% is just the magnets, it is just a low rumble in the pedal and seems to line up when I hand turn the flywheel, it is just more than I expected. The kickr, elite, basically every other trainer uses a different resistance system that doesn't use magnets in the flywheel. Trade offs I guess for faster control and the road feel stuff for Zwift.

In my case it's 10gear sprocket, and rechecked that it's firmly tightened, so are 5mm Allen end caps. Sounds like it might be a resonance of chain and magnets. A lot more than expected, and somehow a nuisance...

Fwiw, I questioned Garmin support on why an O-ring would fix this and just got a reply from Garmin saying that they are afraid the trainer will have to be replaced....Like you my unit is also brand new... quite annoying... I have 10sp ultegra 6700 11-25T with 2 spacers

Try to change the bike, I have tried to change it for my girlfriend's and it doesn't make noise