Zwift Hub setup issues

Hi everyone,
I just received my zwift hub and git some issues.

Disclaimer: my technical knowledge is quite limited.

I have a bulls espresso grinder gravel bike with shimano sora gearset.

  1. Whike setting it up i realized that the distance at the rear was maybe 2mm wider than the wide side of the measuring card. Is that an issue?

  2. After installing the bike i realized its not running smoothly. Its definitely grinding at the front deraileur. I have a 9-34 casette on my bike and git the default 9-28 on the hub. Will this work and i just need to adjust the detaileur or do i need to buy a different casette?

  3. When installing the zwift app i could not find my wheel size which is 700x40c. Which one should i choose?

Thank you in advance and sorry for any stupid questions.


Hey Tonio. Welcome to the forum and congrats on the setup.

It’s unlikely this is an issue.

This may be an issue.

Put the cassette from the bike on the trainer. Matching the cog sizes is an issue. The other: chain and cassette wear. They need to match or you’ll get erratic engagement and poor shifting.

RE: front derailleur, you may need to adjust that a bit too.

Park Tool videos on derailleur adjustment are great. Park Tool Guide to Derailleurs & Shifting: Introduction - YouTube

Unnecessary - while size is a hold-over from wheel on trainers. Should be fine leaving this alone as drive drive trainers calculate speed based on power.

Hi CJ.
Thanks a lot for your detailed response. That helps a lot.

I will need to get some tools tomorrow to swap the cassette and will then see how it goes.


Hi there,
turns out my skills are too limited to fix this unfortunately.

I bought a new casette so that I could leave the other one on my bike wheel.
Bought this one and switched it on the zwift hub.

After installing the bike again I had similar grinding issues at the front derailleur and some grinding on the back one.

So I tried setting up the front derailleur and ended up messing up my setup so that I can’t switch gears anymore.

Any hints whats the best way to start fixing the mess?
I am just a little unsure if I messed anything up in the whole process or if it just needs some finetuning of the derailleuers. Too many variables for someone unexperienced like myself. And it will be kind of hard to bring the whole thing into a bike shop I guess.

Not sure if you guys would be able to help me if I post some videos or pictures?

Well, thanks in advance for any tips you might have!


A general observation that may be of help to others. I received th zwift hub a couple days ago. Setup was ok, only apparent issue was that my rear gap was around 132mm. However set up as 130mm. so far so good. Bike is shimano 11 speed, zwift same. When I put bike on trainer got an awful graunching clicking noise. When the wheel was in gears were perfect. The noise was more pronounced in the bottom two cogs of the cassette. Therefor i had a problem that was n’t very obvious to rectify. First tried the wider rear axle setting. Wouldn’t fit so reverted to 130mm. Second, I thought the noise was coming from the front derailleur. Chain angle from front to back looked a bit extreme on smallest cog. Therefore adjusted front derailleur outwards to get clear air between chain and outer plate. However made no difference. Tried and tried again to adjust rear derailleur to work with hub but would not-clicking and noisy. Three, swapped zwift cassette for my cassette and all ok no noise works in all gears fine. Pretty sure this was not a worn chain issue because. a. inspection of zwift cassette shows that lock ring was damaged, it had been removed before as there was slight damage on notches and brand name was worn out. b. Bottom cog on cassette had two bent teeth, both inwards. This would seem to explain the most noise being on bottom cogs. c. Measure with callipers the distance between rear an front cassette teeth. Zwift cassette 39.01 mm , my Ultegra cassette 38.01. Not sure if this would have any effect. In summary Zwift have supplied on the evidence I can see a previously used and damaged cassette. The width seems a bit odd. The worst part of this is I have tried to contact Zwift with no luck at all. maybe they are victim of their own success?

To move the front derailleur outwards so that the plate clears the chain find the small screw marked H and turn clockwise slowly, should be less than a full turn to move enough, not loads of turns. This moves the plate outwards but do it slowly and only enough so the plate clears the chain

BTW I thought front derailleur rub was a problem but it wasn’t. If you can see clear air between plate and chain as you turn the pedals (either way) its ok