Sram 34T chainring.Is it big enough?

Hi all!
I would like to use Zwift hub with my MTB. I have Sram Eagle xx1 groupset with 34T chainring with 10-52T cassette.
On zwift hub I have the 11-30T-12 speed cassette and I bought a XD freehub assembly to get things work. Not tried yet and but I am thinking to buy something similar to the existing 10-52T, something less expensive to replace the 11-30T cassette.
After I’ve read someone’s post related to a 32T chainring which seems to be too small to create enough resistance especially on flats, I am a bit concerned about spending more money on buying the 10-50T cassette.
Do I really need a big (48T for example) chainring to have similar feel like riding in real world?

@Roberto_Viola wrote an app called QZ that can sit in between the trainer and Zwift and allow you to manage the base level of resistance with virtual gears.

I think you’ll find that the genuine SRAM cassette will offer better shifting than using the Shimano compatible 12 speed cassette.

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QZ developer here, in case let me know if you have any questions :wink:

For most of the time I intend to use the trainer only with my Garmin edge and in this case I quess QZ wouldn’t help. But this could be a part of solution, I will give it a try.
Thanks Paul!

Ok, I appreciate ,
Thank you Roberto!

If you’re not using the Zwift game, I’m not sure whether you will have any problem using the Garmin with it in terms of gearing and resistance, but you do have the option of using QZ stand-alone instead of the Garmin. It does not depend on running Zwift.

Got it! :+1:

Your trainer has the ability to set resistance through ANT+ FE-C. If you are using your Garmin Edge device to control the trainer, your gearing is irrelevant - crank up the resistance to meet your need. There’s a helpful YouTube video (that I’m not allowed to link for some reason) called:
4 WAYS to Use Your GARMIN EDGE With Your Smart Bike Trainer

The folks complaining about a 32T chainring not having enough resistance are probably spinning out on the flat sections in Zwift / simulation mode itself. Super-rough napkin math - on a flat section, 32x10 is probably going to get you to ~23-24mph in simulation mode (aka normal Zwift riding/racing) which is roughly 250-280w at 90rpm cadence, dependent on an enormous number of variables.

I started out trying to use my MTB on Zwift, and eventually it just made sense to get a cheap used road bike. It’s a better experience all the way around and it keeps your MTB free for outdoor use - the fun stuff!


Rex, you gave me the answers for what I was looking for. So, if I can change the resistance on trainer if I am using the Garmin Edge, training in Erg mode is solved. I will look for the video on You Tube.
Yes, you were right, those who complained that the 32T chainring is too small, had problems on flat. If your calculations are correct, maybe I can live with that speed/power or I will look for less flat roads :grinning:
I am planning to use my MTB if possible, I feel much more confortable on it, than on a road bike, but if it will not work, I still have a road bike to use .

Thank you so much for your reply,
Best regards,

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The flats and descents are where you’ll notice the small chain ring. I tried with my 32 up front, 11 on rear and you feel very little resistance when peddling in free mode. Hill climbs are better - ERG works great.

Thus, with 34-10 I still have a chance on flats :slightly_smiling_face:
Thanks Michael!

Let us know how you get on! 32/11 on the hub felt something like 32/42 real world flat. Was spinning like a crazy person. :slight_smile:

It will take some time until I put the trainer into operation. I will have to negotiate with my girlfriend to allow me to install it in the apartment, and I think that will only happen in late autumn when I won’t be able to go out with my bike and I will become depressed. :grinning:
She will probably take pity on me and that will be the moment. Stay tuned, I will let you know about how things works!

I got that down pat. Let wife go out with friends and get drunk. When she come home explain why I need to buy something or set something up, get drunken agreement. Deal is done. :slight_smile:

:grinning: My wife doesn’t drink, that’s another big problem :grin: