8 Speed Cassette Wahoo Kickr Core

Hey all,

Just getting into the whole trainer / Zwift experience, and just want to make sure I’m not doing something wrong, or if there is a better way to install the cassette

I have fit my 8 speed cassette to the Core, using the provided spacer. I then put my bike on it, and the experience wasn’t great to be fair (It’s a cheap road bike from Halfords). I’ve managed to get it so it’s acceptable to work on the mid gears, but at the lower and higher cogs on the rear derailleur it’s not very smooth at all.

I’m gonna get the bike serviced, as it was never really used outside, and have just found that the gear changing was pretty terrible on the road anyway (doesn’t even get to the larger cog on the front derailleur. But I’m also just wondering if it’s worth getting an additional spacer, as Wahoo’s instructions is basically “use the correct spacers”. Thanks - which ones are they?

The cassette I’m using is the Shimano HG50 11-28. Any advice would be very welcome, and whether I need to purchase an additional spacer in addition to a service.


You could take the trainer with the bike to the bike shop so they can check the spacing and indexing on the trainer as well.

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i brought my bike and kickr trainer in for a cleaning/tuning. basically, the trainer has become my back wheel!

the only bummer on this is that it’s super heavy to carry a kickr.

You need one 1.85mm spacer (proper Shimano one is best, the part number is FH-9000 or Y4T724000), situated behind the cassette. Should work fine, with little tweaking necessary if shifting is already good on the actual wheel.

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If you’ve been having problems with the gears on the bike on the road, changing the rear wheel to a trainer certainly isn’t going fix anything… Figuring out if the existing spacer is or isn’t enough is pretty simple, just see if you can move any of the cogs sideways even a little bit by hand, and if not, you should be fine on that front. One extra thing you could check is that the cogs are spaced evenly, some cassettes have spacers with different widths for different positions and they can get switched around easily if you aren’t paying attention.

But overall this sounds to me just like your gears need a bit of adjusting, and if that isn’t enough, you may have to replace something or explore more complicated repairs (checking if the derailleur hanger is bent and what else).


Hey all,

Thanks for the advice. I changed the spacer, and had a new chain fitted which has made a world of difference…Now just to fix the resistance issues I’ve been having!!


Sorry to revive an old thread, but I have a question in regards to a 8 speed cassette on Kickr Core.

I have a flat bar bike that I bought this year. It’s a Diamondback Metric 2. It uses a MTB 8 speed cassette and I just can’t seem to find an extra cassette to put on my Kickr Core. I do see available a Claris road bike 8 speed cassette. Are they interchangeable? Gearing is a bit different, but for Zwift that might be a good thing. The Metric2 is 12-32T and Claris would be 11-32t.

Worked for us (2 bikes 8/9 speeds)

Thanks. Ordered a SRAM 8 speed cassette because I can get it by next weekend. Hopefully I can get it to work.

Hi Chris, I have the exact same issue. I use Shimano Claris groupset with a 8 speed cassette. I install the cassette with the spacer included in the kickr core box, but after trying the setup twice, it just doesn’t feel right. Please note that there’s nothing wrong with my drivetrain if I take it on the road with a wheel, but when using it with the kickr core, it feels off. You said you changed the spacer, may I know what type of spacer you used and what is the length? Is it 1.85mm?

Welcome to the forums @Ekel_Rogusto

1.85mm is correct for an 8sp cassette on 11sp freehub - as you discovered, the spacer that comes with a Kickr is for 10sp cassette.

I’ll make another apology for reviving the thread. I just ordered the Kickr and have a 1990’s Cannondale R500 I’ll be connecting. It has an 8-speed cassette. Will I need to order the Shimano spacer mentioned in this thread (Y4T724000)? Anything else I should do/order to complete the merger? TIA.

I wanted to provide this information for anyone trying to understand if they need the Y4T724000 spacer. For the current 8 speed Claris compatible Shimano cassettes there are rivets on the back, that will cause the cassette to wobble, if you use a flat spacer. You can either file down the spacer where the rivets line up, or get an OEM spacer. The OEM spacer is notched to align with the spline of hub making it easier to get everything set up. I am not sure if this is true with other 8 speed cassettes like Sunracer’s; I have only had to opportunity to use Shimano 8 speed cassettes on my trainer.


Hi Mark,
I have the same wobble problem, what OEM spacer did you get?

Hi @Giles_Morrison, the SKU is Y4T724000, you might see it listed as the FH-9000 also.

Thanks, think i’ve ordered the right one…

No problem, hope it helps.