12spd mtb on a direct drive trainer? or just use old road bike?

Equipment
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So this year I really want to upgrade to a direct drive smart trainer to improve my training and also to try zwift racing. Also I am definitely focused more on mtb racing and so I like to ride my mtb for everything. I initially wanted to use my mtb on the new trainer, but after some googling it seems like it isn’t going to work that well. (my mtb is an epic hardtail, 32t 10-51, SLX 12spd, boost148)

Some trainers won’t even accept a 12spd shimano mtb cassette, and then people say that in Zwift, a 32t chainring will be way too small and you’ll be spun out often. Shouldn’t matter for trainerroad workouts with erg mode, but I guess it’s different in zwift racing?

I do also have a 2x9 road bike, which I guess should be the obvious choice, but I find my mtb a lot more comfortable. Though getting a 9spd cassette would be far easier and cheaper.

Is there a way to use a mtb on a direct drive trainer? Or am I better off just using my old road bike?

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couldn’t you get a swift cog?

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Does that just work on any trainer? I didn’t realize that

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I don’t know the exact details but more and more trainers are being released with a version that has a swift cog. Instead of no cog or some shimano cog…

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Hera are the current Zwift Cog compatible trainers:

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Yeah, for racing you’ll find yourself at a significant disadvantage. Zwift racing simulates racing in the “real” world, so you’ll have a 32t CR vs. riders in road bikes with 52t CR. You wouldn’t be able to compete IRL with that gearing and the same would apply for Zwift.

Fine for TR because you’ll be in Erg mode.

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How odd that the old budget kickr core is compatibel but not the newer and/or more expensive/premium kickrs like the v5 or v4…

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Good to know, it wasn’t super clear to me that the chainring mattered. Thought you could just increase resistance or something.

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Shame cause I was looking at the Saris H3, and it’s not compatible.

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If you use the Virtual Shifting in Zwift (with the Click controller that comes with the Cog) the app makes an adjustment to work with a range of gearing, including MTB sizes.

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So if I get a zwift cog trainer then I could use the mtb in races more effectively ?

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Yes, that’s what I’ve understood by the Zwift info and various reviews.

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If anyone is curious, I found this on the zwift forum from a zwift employee.

"Shuji at Zwift HQ. The short answer for you is you can use your mountain bike because of the way virtual shifting works in Zwift.

While you pedal during the ~10 seconds or so after you spawn, the trainer will read your cadence and its own flywheel velocity to calculate what physical gearing is on your bike, then set your virtual “12th gear” in game. That is right in the middle of a virtual 24 gear range.

This is to say that if you have road bike with a 53 / 39 double crank or a modern 1x mountain bike with a 30 tooth front ring, that virtual 12th gear will produce a similar feeling of resistance.

The real gear detection happens only once per ride, when your avatar spawns."

Sounds like I’d be best off with a cog setup, but still I found a good deal on a saris h3 and it’s not compatible with the cog. The cog trainers seem to cost a few hundred more in Canada.

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I haven’t looked thaf much into recent snart teainees but the h3 seems lije a premium teainees witn a cost of around a kickr v6 but as someone who thought he had to upgrade from a kickr core to a kuckr ( v5) i can say that that upgrade wasn’t worth the mkney.

A kickr fore/jetblack is probably enough at a fraction of the cost

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I’m running this combination since 2021. H3 with XD adapter and 12 speed cassette.

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So you are using your mtb with the H3? How does it fare with the small front chainring in zwift? And what cassette? cause it says max 42t cassette

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I just use a Shimano 12-speed road cassette on my KICKR with my 12-speed MTB.

It works perfectly fine for me. :man_shrugging:

I don’t know for sure what you’d have to do to ensure you’ve got “enough” gearing on Zwift, but I imagine it’s possible…

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So there’s no issue with shifting with the smaller cassette? I would have thought the derailleur wouldn’t be compatible with a road cassette. What derailleur and cassette specifically are you using?

I get why they created the zwift cog cause this is all pretty confusing

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They aren’t technically compatible according to Shimano, but I’ve had no issues using an XT shifter, SLX derailleur, and 11-30 and 11-34 12-speed Shimano road cassettes.

I don’t foresee any issues with this setup on a stationary trainer. :man_shrugging:

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Nice I might try that first then. If I don’t like it then I can try my road bike instead. Probably strange for most people, but I’d much rather have my mtb on the trainer.

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