It seems really lazy of Wahoo not to fix this.
The issue is caused by them providing only one adaptor for both 142mm and 148mm thru axles and using the raised central section to change the effective axel width when you insert it the other way round.
They could easily supply additional adaptors for each axle width where the raised section is much slimmer…
Looking through this, I think your best bet is to locate a lathe and machine the larger diameter shoulder back a few mm until it will fit cleanly. I’d start asking around - friends, friends of friends, ask at the LBS. Someone has a lathe and, as others have pointed out, this is a 5 or 10 minute job. Just pay 'em with a couple of 6-packs.
This is what happens if you have blind faith in both Trek and Wahoo being compatible. I had this tightened up and solid on a Wahoo Kick Core for about 3-4 months.
Oh dear… 
@r6evo what frame is that?
2021 Trek Emonda SL6. I Have sanded down what i can without ruining the carbon and have put a layer of epoxy Resin on it. I will be doing another soon to make sure its protected.
Looks like i will be Turboing on the TT over the winter.
So I’ve been riding my SL6 pro on a Kickr Core for a few months now, naively working on the blind assumption that the two were compatible (oh how wrong I was).
There is a slight mark on the frame, near non-ds dropout but nothing substantial yet - big thanks to you guys for spotting this, more than likely saved my frame!
I’m going to attempt to modify the adaptor, but if anyone else finds any other workarounds please do share!
See this post (although it in korean you will be able to understand what needs to be done to the adapter)
Good find!
Just reminder that after this operation adapter won’t work as 148 adapter.
2021 Trek Domane now added to the list of incompatible frames to be used on the 2018, 2020 Kickr V5 and Kickr Core
The other incompatible bikes are the 2021 Emonda; 2021 TCR Advanced Pro Disc and all Canyon Ultimate rim brake bikes.
Going by other forums, they appear to be chewing up the rear drop outs
Sadly, I can confirm this is happening on my 21 Domane SL5 with a Kickr 17 (which I think is considered the V5 - edit, it’s the v3 thanks @mcneese.chad ).
Definitely a massive disappointment to have this discovered months after purchasing the bike.
Nope, V3
https://wahoofitness.yonyx.com/y/conversation/?id=c6bbde00-be88-11e7-b908-bc764e10c19d
Having cleared that up, to the best of my knowledge, this problem exists with the 2017 (V3) and newer models that were the ones that allow native use of a thru axle. I believe the 2014 & 2016 required a different adapter setup, and I have no idea how that interfaces or compares with the issues above.
Hey all, just want to point out this is also the same fitment issue with our 2020/2021 Domane as well if anyone with those comes across this post (which I see one user already commented). Also, Wahoo is looking into this to find a solution - so we could see them create a proper fitting adapter to work with these models soon.
It seems like one could remove the extra material with bench grinder or similar, no? A lathe would make it look pretty but that doesn’t seem necessary.
For what it’s worth, I submitted a ticket to Wahoo and received the following feedback:
The 2021 Domane is indeed incompatible with the kickr line of smart trainers, due to the dropouts in the device.
Please discontinue use as it can result to damage of your bike/the trainer or both.
At this time we do not have a planned solution in place to make the Domane compatible with the Kickr.
Unfortunately, you will be unable to use that bike safely with your current trainer.
So, if they are looking into a solution, they’re not able to publicly say that right now.
Hi,
I have neither a Trek bike or a kickr but I had also an issue with my Tacx and my Focus bike. I found a solution here: https://robertaxleproject.com/
If they don’t have anything yet maybe its worth asking.
Good luck!
Hi All,
I’m new to these forums but have listened to TrainerRoad podcasts for a while now so thought I would sign up. 
I have a new Trek Emonda and Wahoo Kickr Core on the way, I ordered these two products before knowing this incompatibility unfortunately. I reached out to Wahoo too and got this response:
Thank you for reaching out to Wahoo Support. At this time we are exploring options for future compatibility, but we do not currently support or have any information on when this may be available. I would definitely encourage making sure other trainers fit as well because from what we have seen the new dropout design has a tendency to contact axle adapters.
I have passed this on to the product managers to evaluate.
Lets hope they create a solution soon!
Cheers
Yea, it’s not something I know of completely either and I’m sure most of their CSRs don’t know. But fingers crossed for you Wahoo users they have something in the grapevine!
I think someone mentioned above - you could use a bench grinder to take off 6mm from the 142 side, then use the 148 side, which would clear the outer flange in the dropout (if I’m understanding the current incompatibility correctly). The other would be to use a nut and bolt combo to basically make a standard drill into a lathe. Tighten the Wahoo 142/148 adapter down in the nut/bolt, and use the protruding bolt to fasten into the bit chuck. Clamp the drill down to a workbench, grab a rasp file, and off you go. It might take a while, but you could end up with a DIY fix fairly cheap.
