Freewheeling not working on Zwift Hub One?

I just set up my Zwift Hub One but as soon as I stop pedaling the chain curls up because the Zwift Cog keeps turning. Did I do something wrong on the setup or is there any fix? Thank you!

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Hi @MaWi
Can’t tell from that GIF, but did you install different axle adapters (i.e. QR type to thru-axle type or vice versa)?

If the freehub body was removed during that process - check if a thin shim was installed inside. If yes - that shim probably belongs on the outside of the freehub body, under the drive side thru-axle adapter.

Hi @shooj
I installed the green thru axle adapters with the green color not poking out because the distance is 142 mm. Hmm, I remember there being some round, silver shim falling out when removing the quick axle adapter, where does it belong? Here’s a pic of the drive side and non drive side:


And here are two shims I found. I got the hub one from my father in law who disassembled it yesterday.


Did your FIL remove the freehub body from the trainer? That’s the heavy chunk of steel with the three pawl teeth on the back.

If so - you’ll see an aluminum sleeve that slips over the axle.


Is there a thinner shim that’s next to that sleeve?

The black spacer marked 1.8mm is not needed with the Zwift Cog. That’s installed behind a 10 speed cassette instead of the Zwift cog.

Can’t tell if the sliver spacer is the same diameter as the black 1.8mm spacer in these separate photos. If they are the same diameter, it’s stacked next to the black one when when an 8 or 9 speed cassette is installed.

The shims are the diameter but then these are not missing on the cog as you mention.

BUT! I found this piece of metal in the box – might this have something to do with it? Does it have to be inserted in the drive side or non drive side? I guess drive?!

That is the non-drive side adapter for mountain bike frames with a 148 mm frame spacing. It also looks like a Wahoo trainer part, not from a Zwift Hub. Does your FIL also own a Wahoo trainer?

The cause of freehub not rotating is between the trainer and the freehub body. Most likely suspects are:

  1. the thin shim I’m talking about that doesn’t belong there
  2. the three pawl teeth aren’t ratcheting smoothly as they should

Both of these possibilities will require that you remove the drive side axle adapter. Instructions are similar to this video, except you do not need to remove the Zwift Cog from the freehub body.
Slide the Zwift cog + freehub body off of the axle.
Show us the back side of the freehub body - how do the three pawl teeth look? Do they move easily? Please post a photo.

Then: look at the axle of the trainer - there should be one sleeve like in the photo above. There should not be a thin shim stacked against that sleeve. If a shim is there - remove it.