Sram 12 speed on zwift hub trainer

Hi Leonard,

I was lucky enough to purchase a Jetblack Volt XDR freehub before they became unavailable. I also purchased a SRAM 12 speed XG-1250 10-36T cassette. I followed the instructions/video provided by Zwift to properly install the freehub body. Once that was installed, I installed the cassette. (there are lots of videos on youtube on how to do this.)

My bike is 142mm thru axle, so I configured the hub with the appropriate adapter.

I am not sure if I am answering your question. Please let me know if you need any additional information.


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Got almost the exact same setup (1270 here) with some strange noises (rattle) on the last 3 cogs as well. Have you found a solution yet?

On a related thread, @Roberto_Viola offered to enhance the qdomyos-zwift app to support the Zwift Hub, so you can manage the base resistance through a 3rd party app. That’s probably the only way this will be addressed in the short term.

The problem with gear noise in the last 3 cogs is probably an adjustment issue. If you’re using the XG-1270 I assume you found an XDR freehub for the trainer?

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Hello Michael,

thank you very much for your respond,

I have exactly the same configuration as you now (with the jet black freehub).

However a problem persists, when I stop pedaling the chain relaxes enormously, as if the freewheel did not fulfill its function.

Have you ever encountered this problem?

thank you in advance,

Léonard

I haven’t used the JetBlack freehub, but in general when you get a slack chain while freewheeling, it means that the freehub ratchet has too much internal resistance. It may benefit from using lighter lubrication. Excessive grease can also cause this. It may also get better with time as the springs wear out a bit.

EDIT: some other things that can cause freehub drag:

  • No lubrication of the pawls
  • New dust seals
  • Excessive torque when installing the freehub

I have only noticed slack chain once. I was trying to unlock the 100 km/h achievement. I was going full gas in my 12th gear. When I stopped pedaling, my chain slapped the chain stay. Thank goodness I have frame protection. Unfortunately, I didn’t get the achievement; I think I need a different bike and wheels, and more power. :grin:

When I installed the freehub and cassette, I added some extra grease. The specific grease I used was Zipp Freehub Pawl grease, and I followed the instructions/advise of GPLama in one of his videos. I also made sure I was using the correct torque when attaching the freehub (6 Nm) and the cassette (40 Nm). 6 Nm isn’t much. Do you think you may have over-torqued your freehub?

Good luck in getting this fixed!

EDIT: Paul’s post above seems very helpful too. There was almost no grease on the JetBlack XDR freehub out of the box. I’m wondering if it would be beneficial for you to uninstall everything, clean everything, re-grease, and reinstall.

I just got off a support chat after encountering this issue and they recommended I use the SunRace CSMZ90 WA5 11-50 cassette, has anyone tried it"

sunrace (dot) com/product/csmz90-wa5/

I haven’t, but it looks like a copy of the SRAM PG-1230. It should be fine but if you want to be certain of perfect SRAM compatibility, the PG-1230 provides it.

That issue (binding of the freehub and slack in the chain) could also be caused by too much clamping force from a QR skewer, or an over-tightened thru-axle. Check that you haven’t cranked down on either of those too hard–loosen the skewer/axle a bit and see what happens.

I am using the 12 gear cassette Zwift Hub with my SRAM Force equipped bike. For the most of the gears switching works quite ok, for some gears I need to do some multiple shifts to get the correct gear.

I will use this setup until there’s a proper fix.

I think this is the part you need. I can’t swear to it but from the description it seems likely. I have no experience with this seller.

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Paul, respectfully, I do not think this is the correct part. The picture and silver color match the 11spd XD driver for a Whisperdrive trainer, which I think may be discontinued. The Zwift Hub is essentially a rebranded JetBlack Volt. I’m 99% confident that the correct HDR driver is this:

www.jetblackcycling (dot) com/indoor-cycle-trainers-and-accessories/jetblack-volt-xdr-freehub-body/

It would be great if Zwift would sell a cassette-less version of the Hub with this driver…

Yep I am not positive about the part compatibility. Availability has been really bad. I doubt Zwift have been able to get it. Probably a good idea to ask Jetblack for compatibility advice.

I’ve had the same issues as above. I have the SRAM Rival AXS 12-speed and its clear it doesn’t work. I managed to get hold of a XDR freehub from Jet Black and it still doesn’t work. It simply is not compatible despite the marketing pitch and under any other circumstances a company would be compelled to pull the misleading marketing. The Zwift folks have tried to help me and one person has gone above and beyond to find solutions, but it should now be clear that it is not compatible.
Their problem would be how do they admit this without a clear fix.

I have a SRAM Rival as well and just a conventional home trainer but I experience the same vibration in the last 3 cogs. Maybe this is not a trainer problem but a SRAM issue?

The SRAM 12-speed cassette doesn’t work on the Zwift Hub, only spinning on the first three easiest gears. It’s simply not compatible.

did you try with the qz app? you can increase the resistance using the gears tile!

So… same issue. SRAM isn’t working.
And this is stated on the Zwift website:

Q: Does Zwift Hub come with a cassette?
A: Yes! We’re glad you asked. Zwift Hub comes with your choice of pre-installed Shimano- and SRAM-compatible 8, 9, 10, 11, or 12 speed cassette—or no cassette if you prefer to install your own.

To make a long story to a short …. Zwift hub trainer sucks with sram 12speed… so buy a tacx or elite as alternative …. “Cheap is expensive purchase”

8, 9, 10, and 11 speed SRAM should work well with the cassette they offer. They shouldn’t make claims about 12 IMO.