Thru axle on trainer - wobbly AF?

Okay so here’s the deal:

I bought a 2021 Emonda and found out afterwards that there are fit issues with my Wahoo Kickr. Wahoo sent me the adapters that they made to fix the issue, but I’m still having the same issue.

So…I bought an H3. Same issue.

If I have the bike “secure” (meaning it doesn’t wobble) then everything is so snug that the cassette wont rotate.

If I loosen the skewer to where the cassette will rotate, then the bike is wobbly and I’m worried that, over time, it’ll damage the frame. It’s not terribly wobbly, but if you were riding on the road and your rear wheel felt like that you’d stop your ride. I’m talking wobbly to the point that you can rock the bike back and forth, and that’s just with the cassette BARELY able to turn freely.

So my question is this: am I just being too picky? Are bike with thru axles on trainers just not able to be snug?

At this point I’m ready to just get rollers and say F’ it to direct drive trainers all together.

  • No, wobbly is not intended or acceptable. You want a secure connection to the trainer.

Are you absolutely certain you have the cassette installed properly? Most important is the need to install a standard 11s cassette (Shimano) without the 1.8mm spacer that ships with the trainer. If it’s installed on a regular 11s cassette, it would likely bind as you are describing.

1 Like

That’s what I thought but I wanted to check.

I’m 100% sure the install is good. I’ve had that Kickr for years and used it with my Speed Concept with no issues at all. I installed a brand new cassette ( bought it this afternoon actually) on the Saris H3 (removed the rubber band and spacer), triple checked that the right adapters are on both sides. Still same issue.

At this point I’m thinking it’s the Emonda and not the trainers, since there was a fit issue with the Kickr that they had to machine new adapters for, I think its safe to assume there might be a similar issue with the H3, too.

Just kind of at a loss. Haven’t been able to get a trainer ride in in about a month and its getting on my nerves. Seriously considering rollers.

1 Like

Sounds like you covered the bases. Close inspection at the frame to see where the contact is happening is something that may be interesting to learn.

But you may well be dead on that the bike may be the root problem, sadly.

Yeah I’m thinking I’m hosed.

@Jonathan what rollers do you suggest?

He is still on the Elite Quick-Motion AFAIK.

1 Like

I second checking the cassette. I recently changed mine and in order for the pedals to turn, my thru axle needed to be slightly loose (like 3/4 of a turn), leading to some wobbles. I realized the cassette was not on all the way. Fixed that and everything is good.

Good luck!

Some things to check…

  1. You don’t have the trainer end caps reversed. Youve got the 142mm setup going vs the 148mm. You’ve got the end caps tightened (screwed) down all the way?
  2. the free hub is all the way into the trainer body? Between the cassette and the trainer you shouldn’t see the pawl mechanism. It can also get hung up on the axle spacer inside there. You should be able to push it in 1-2mm and it should spring out.
  3. the little cog is stirring on the free hub right. Some times it seems like the little guys is on the splines, but it’s not.

Well it would mean that I’d have cassettes on 2 different trainers installed incorrectly, which would make me feel like a complete moron, but it’s worth double checking.

On the Kickr they just slide in, and on the H2 they tighten pretty securely and completely. I’ve even actually tried reversing them intentionally to see if it improved the fit - it didn’t.

I can double check the hub - worth a shot.

I’ll double check the cassettes but I’m 99.9% positive they’re good to go. Again anything is worth trying.

What seems to cause the cassette to not rotate? Is it just too much tension through the axle and the bearings seem like they won’t spin? Or is it contacting the frame or something else and being blocked from moving?

The first seems pretty unlikely since you can usually snug up those axles pretty tight and my understanding is that the bearing configuration isn’t too far off that of a regular wheel.

So this morning i rechecked the cassette, spacers, lock ring, and adapters. Everything was right so I decided to try swapping the cassette for a Jew one. I yanked off the sunrace cassette that came on the Kickr when I bought it and put on a 105 out of the box.

Zero issues, spins freely in both directions and the bike is snug as can be.

I guess the the 105 might be a few mm’s shorter than the sunrace and that allows for enough clearance? Shrug

Either way, it seems to work.

1 Like
  • :1st_place_medal: WINNING!!! :crown:

The sunrace cassette might be designed to not need the spacer?