Tacx Flux 2 with two bikes

Hi all,

My wife and I are considering to buy a direct drive trainer, the Tacx Flux 2 notably.

Problem is, we have different speed-gears. I have an SRAM 10speed PG1070 and my wife has a Shimano 11speed CS5800.

What is the cheapest way to make sure both of us can use the Flux to its full capabilities (so not just ERG). And what is the best price-quality/future proof way? My driveline already has about 4000kms.



the cheapest way is to switch cassettes on the trainer, but that’s far from convenient…
I would try to force ERG mode on 1 of the bikes (with a different cassette). The bike with the matching cassette can be used in all gears.

You can use TR just fine in ERG only.

Upgrading from 10 to 11 speed will cost you quite some… (chain, cassette, derailleur, shifter). But that’s the most complete solution

I was thinking this recently with a 9 and 11 speed and decided not to bother, but aren’t 10 and 11 very close in size? You could potentially use the 11 speed thinner chain on the 10sp cassette as long as you both keep in one gear / erg mode? I may be wrong if someone can correct me

11 speed chain does indeed work fine on a 10 speed cassette (except the shift indexing is off, so indeed ERG only in the the gear that doesn’t require fiddling with your indexing). I think the other way around might also work, a 10 chain on 11 cassette could potentially rub against the bigger cog… but with a straight chainline it might just work.

(the inner width of 10 and 11 speed chains is the same, only the plates are thinner)

Yeah the cheapest would be to have 2 cassettes and to swap them out for the correct bike but that is far from convenient.

The second cheapest way would be to upgrade your 10 speed bike to 11 speed. An entirely new Shimano 105 groupset can be had for under $500 with brakes (that was just the first google link). So not super cheap but cheaper than a second trainer

Time to check with the wife how often she will want to do sth else than just ERG then :wink:

Thanks all.

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I should say that that price is for R7000. You could probably find a R5800 groupset for cheaper than that.