Compatibility between two bikes and one Kickr

Apologies if this has already been asked here (I did a quick forum search and came up empty):

What do I need to know about direct-drive trainers (say a Kickr Core) and compatibility with multiple bikes? I am looking for new bikes for me and my partner, and I’m still learning about groupsets and gearing.

I have a good idea of what kind of bikes we want to get: entry-level gravel like the Liv Devote for my partner, and a bigger investment gravel like the Trek Checkpoint, Specialized Diverge, or Giant Revolt Adv for myself.

Indoor cycling has been so good for my sanity, especially in these times and in the Midwest winters, and I know I’ll want to upgrade from the Kickr Snap to the Kickr or Kickr Core. I want to be sure that it’s not a pain for my partner and I to swap bikes on the trainer. Maybe it’s silly to decide on what bike to get based on how it will fit on a trainer, but I really value simplicity and I don’t want to have to buy a whole bunch of accessories and make adjustments every time we want to swap bikes.

For example, would I want to look for bikes with the same number of gears in the back, like 10-speed or 11-speed? Or is it important for the component “level” to be the same (e.g. both bikes having Shimano GRX, but one has RX-400 2x10 and the other RX-600 1x11)?

Ideally you want a common cassette, so the same speed (10x, 11x etc) and a compatible manufacturer (which is pretty much everything now), beyond that it doesn’t really matter.

You can find some cassette/speed combinations that can work together but ideally you wouldn’t.
You would really need to be careful maintaining both chains though, because you don’t want to get to a point where one bike’s chain is wearing the cassette in a way that then wears the other bike’s chain and you’re accelerating the wear on everything.

That said, the above assumes you’re slipping bikes fairly regularly, otherwise if it’s only occasional then you just want matched cassette types Shimano/SRAM or Campag and you can swap the cassettes as you install the bike.

2 Likes

Some entry-level bikes come with 9x (I’ve seen Shimano Sora 2x9). I read somewhere that a 9x would not work with a direct-drive trainer. Is that correct?

No, not even close.

The Kickr comes with an 11x cassette installed (Core with no cassette).
I’m currently running an 8x setup because it was the bike with the closest geometry to my main outdoors bike that I could afford to just permanently leave on the trainer. I’ve used a 9x too.
8x required additional spacers to get running cleanly, but those are an easy online purchase from eBay / Amazon / wherever, other than that it has all been fine.

1 Like

I use my Aeroad 11x on my Kickr Core. When my son fancies a go (he’s 9) I swap the cassette on the Kickr and hook up his 7x MTB. It takes a few mins max to change the cassette and works perfectly. It’s seamless.

1 Like

Thanks for that example!

Take a look at the Wahoo support pages for their trainers for bicycle compatibility info. For example this page about the KICKR: https://support.wahoofitness.com/hc/en-us/articles/4407140853650-Bicycle-Compatibility. I would assume they have similar information for the Core. You will definitely want each bike to have the same size cassette. My KICKR came with an 11, but my 15 year old bike has a 10, so I had to change the cassette. Not something you want to do frequently.

On a KICKR (not sure about KICKR Core), you can definitely run anywhere from 8 to 12 speed “standard” shimano compatible cassettes and, if you swap the freehub body to the SRAM XDR, all the new SRAM cassettes too. I have a shimano 8-sp on my KICKR.

It will be easiest to have the the bikes run the same brand and number of gears on the cassette. The cassettes do not have to be the same gear sizes (eg I use an 11-28 cassette on my KICKR but the bike has an 11-31). Then it is fairly easy to swap bikes—just take one off the KICKR and put the other on). A hint from my swapping: it’s much easier if you put the bike in its biggest gear first (ie smallest cog on the cassette).

If the bikes don’t have the same number of speeds (eg 10 v 11), you’ll have to change the cassette on the KICKR every time you change bikes. While doable, that is a much more involved process than just swapping bikes and requires appropriate, although not particularly expensive, tools. This is only practical if you like doing this sort of thing or do it infrequently.

If you have incompatible cassettes that require different freehub bodies (the part that you mount the cassette on), you’d have to swap those too. I’ve never done that. It requires more tools and really isn’t practical.

Can confirm Core supports 8-speed.

All we need now is a Campag N3W adapter for 13-speed :slight_smile:

Ideally you would want bikes with the same gearing as changing the cassettes would take a while. Also bikes with the same axles although changing the axle adapters is far easier than changing the cassette

1 Like

Drop out spacing is another one to consider, my kicker core can switch from 130 to 135 with 60 seconds of effort but it’s a small detail to think about.

Also a question to consider is how different are you in size? Could getting one bike you can both use and setting that up on a trainer permanently work better? Than all the faff of cassettes, axle types, dropouts and switching around.

Appreciate all the tips and advice on this thread. Here’s what we went with: gravel bikes that fit us that were available at our LBS!

We’re proud owners of a 2021 Giant Revolt 2 and a Devote 2 (non-Advanced, aluminum versions). Given our budget and the fact that these were available at the same shop (and how so many bikes are not available these days), we went for them.

As far as trainer compatibility goes, we both now have bikes with the same Sora 2x9 setups. I think this means either Kickr or Kickr Core with a 9x casette will work! For now, we’ve got our old road bike on the Kickr Snap. Next winter we’ll consider an upgrade to one of the direct-drive trainers. Early holiday present to myself, perhaps. :slight_smile:

2 Likes

Congrats on the new bikes. When you get your trainer, just buy a 9 speed cassette and put it on, with the spacer included with the KICKR, instead of the 11 speed it comes with. You local shop can do it if you don’t have the tools. You’ll need a lockring tool, a chain whip, and a largish adjustable wrench to remove/install the cassettes.

1 Like