Zwift Hub gears wont index

My gears are perfectly fine on my bike but they are all over the place on the zwift hub. Ive reindexed them while on the hub and they range from grindy to completely wrong, nothing I do fixes the issue. Any help greatly appreciated

What drivetrain are you running? Have you checked your derailleur hanger alignment?

Im running an 11 speed 105. Yea my hangers fine. Everything works 100% on my actual bike. I spent a good few hours trying to index it but just no luck. Ive had 3 rides on the trainer and the issues have varied across each of them

Most likely the cassette is positioned differently in relation to the frame on the trainer compared to your rear wheel. It can often be resolved by playing with freehub spacers until they are the same. A bike shop can help sort that out if you’re not comfortable doing the work.

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Different levels of wear between chain and cassette will cause sub-optimal drivetrain performance.

Remove the cassette on your bike and install it on the trainer to eliminate that as a cause.

There have also been reports of poorly manufactured cassettes being installed on some Hubs. (like “incorrectly machined teeth”) Those would account for drivetrain issues, and be resolved when you swap a known good cassette in, provided it’s indexed correctly.

I’m having the same issues . Everything fine on road once on hub its grinding and rubbing .

Any direct drive trainer can have this problem, due to the sensitivity of getting the cassette fully aligned with the drivetrain.

i just have a clunking noise now , gears indexing on road and hub . But on the hub it makes a clonking noise.

Noticed that its coming from the alignment from hub to the front
Cassette .
Its miles out .
Dont really to keep messing around with the gears when changing from road to hub .

I have the same issue on my Hub that was delivered yesterday… my ultegra R8000 11 speed gears are indexed perfectly on the bike but when mount on the Zwift Hub I can’t get into the smallest cog. Can you please explain how you fixed this?

I wonder what the spacer in the bag is for?

That spacer is for 8/9/10 speed cassettes. If you can’t get into the small cog then the cassette is spaced too far out relative to the derailleur. If no spacer is installed, then the solution would be to adjust the derailleur for how the trainer is, and add a tiny spacer on your rear wheel so they are the same.

(Sorry earlier edit of this post had it backwards)


I had a similar problem, I couldn’t get into the largest cog on the supplied cassette. I decided to switch to the 105 cassette from the bike. When I removed the supplied cassette I found out there was no spacer installed, there is one on my 105 cassette. Once I got the 105 cassette with the spacer on I didn’t have any issues using all 22 gears. Wondering I’d there should be a spacer with the original cassette.

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The spacer is intended for use with 8/9/10 speed cassettes, not 11/12. But it’s not unusual to find a difference between a rear wheel and a trainer in terms of where the cassette sits in relation to the derailleur. The same problem can be found with two different brands of rear hubs. Usually a spacer that thick will be more than you require, but if you get enough threads engaged on the lockring it’s not a problem. If there are not enough threads engaged the lockring can come loose more easily or strip the few engaged threads.

Same problem here with 105 11 speed setup on road bike and gravel di2 also 11 speed. Indexing fine on bikes but out and problems in high gears on hub. Read forums, decided to try the bike cassettes instead of Suntour cheap suppled cassette. What a difference! Distance of outer cog 1mm more lateral on Suntour being the cause. Zwift need to address this or add a whole section in their otherwise good instruction manual on how to index gears to the supplied shite cassette


yes, much the same. Sram Force 11-speed just done 80-odd km in norfolk, all fine. Popped onto my new Hub (which is great) but out of ERG mode I have plenty of slipping and clunking. Shame if I need to chuck £60 more to get a proper cassette.

Not to be pedantic but the cassettes that ship with the Zwift Hub are “Sunrace” not “Suntour”. The latter would likely have been fine but “Sunrace” is more likely to have quality-control issues.

I get it - Zwift needed to keep costs down and many people don’t have problems but the Sunrace cassette should be the first thing to get swapped for the bike’s cassette if it’s skipping.

Yea I ended up getting this sorted by replacing the cassette on the zwift hub with the shimano cassette from my bike and buying another shimano one for my back wheel. £60 to sort and Zwift gave me £40 and 2 months sub for the inconvenience, so can’t complain.


Hi all. Just received my new hub today. Also having a mare with the gears. It’s set on the smallest cog on the bike but when I swap it too the hub it will not go past the 5th smallest cog? But when changing up to the largest cog it’s fine. I was expecting it to jump off but it’s fine. Just will not get past the 5th smallest cog? Very dissatisfied at the moment!

Hi @John_Killiner

Welcome to the forum.

We will need a bit more information to be able to help. What cassette is on the bike wheel and what is on the Trainer, Also what groupset are you using on the bike?

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What happens when you manually pull on the derailleur (while turning the cranks) to get the chain to the smallest cog? Can you move it that far? If so, does it just go back to the 5th when you release it (still while turning the cranks)?

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