Using a 7 speed bike on a 11 speed cassette built on Kickr Core

Hi there,
i´ve installed a 11speed cassette on my Kickr Core to be used with my 11speed bike.
As im using outside quite often, i decided to get a dedicated cheap bike for the trainer.
The new bike has 7speeds (2x) with a Shimano Trouney derailleur.
My question is, can i keep the 11 speed cassette on the trainer and simply adjust the derailleur to access only 7 speeds on the trainer, or this wont work? i wont be using the original bike cassette noir switching between trainer.

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I did this with an old road bike on my first kickr and it worked. But w chain disparities and a love for level mode, i eventually just picked up a spare 9spd cassette used for like $15 and installed that on the Kickr.

If its a “dedicated” trainer bike, do you have the 7spd cassette you could mount?

thanks a lot for helping out.
it will be a dedicated bike. i could transfer the 7s cassette to the Kickr Core if necessary, i was just thinking of leaving the 11s on the trainer and adjust eh derailleur accordingly. I read that for a 7s i would need to add spacer on the Kickr Core.
thanks again

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Yup, would work, but the big problem would be trying to run an 11spd chain on 7spd rings (or vice versa) with that big a disparity you’ll get a lot of slippage on one end or the other unless you jist find the sweet spot and run one gear in Erg mode.

Honestly not even aure you could get a 7spd chain to seat on an 11spd cassette.

ahh, you are right, i forgot about the chain :P.
well, but my idea was to use only the 7 clogs on the 11s speed cassette. it should be the same right? i wont be accessing the 8-11 clogs…

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Right. But again, the issue would be chain link dimensions for an 11spd chain being too narrow for your 7spd rings, causing the chain to slip the rings, or too large dimensions of a 7spd chain not being able to seat the narrow 11spd cassette profile - again causing slipping.

When i did my initial 9spd to 11spd cassette setup, i compromised and ran a 10spd chain, which mostly worked on both ends. Not sure a 7spd could handle that either. Best option (IMO) is seating the 7spd cassette w spacer (and yeah - you need the spacer ring) on the kickr.

Go YA! i will do some trials…icant destroy the thing…i guess.
if possible i will try to see if can change the cassette in the shop for an 8 speed one. so then i just have to adjust the derailleur


5-8 speed chains have an inner width of 2.38mm, 9-12speed are 2.18mm inner width. Your 7 speed chain will jam on a 11 speed cassette, I just tried with some bits from my spares box.

7speed sprockets are 1.85mm thick so theoretically you could use an 11speed chain, but you’d need to buy one.

The sprocket spacing on 7spd is 5mm, 11spd is 3.9mm, so even if you use the 11spd cassette with an 11spd chain the indexing won’t work. You’ll have to adjust the trim to stop the chain jumping around in every gear, so effectively creating a singlespeed as changing gear will be a complete pain.

the cheapest most sensible option is just to use a 4.5mm spacer to fit the 7spd cassette from your new bike to your Kickr Core


after installing a 7 gear cassette with some spacer, the system was “working” overall. BUT,
on high gears, i have that grinding feeling (vibration on the pedals). after several attends, looking to all possibilities (screw limit adjustments, cable tension, indexing, etc) i think i found the issue. the chain pins are rubbing slightly the “inner wall” of the cog. this makes a not perfect alignment of the chain in the cog teeth. So, i decided to remove a 0,5mm spacer to bring the cassette inwards to the hub. The problem is that now i have a little gap and the cassette its not tight to the Hub. Maaan. Adjusting the rear derailleur doesnt work. the chain alignment, coming from the biggest chainring is not 100% aligned (when pedaling backwards i can see clearly). Or im doing a mistake analysing it on the back pedaling? is the rear derraileur that should drive the chain alignment to the cassette or the cassete orientation in the hub . I guess im overthinkg and wrongly :(. So, perhaps a more clear question (sorry for this), if the cassette is tight to the hub, chain and cassete are compatible, is the rear derailleur only that should adjust the position of the chain on the cogs? thanks for any insight

If you are using the 7spd bike with a 7sp chain and cassette on the Kickr. The limit screws and indexing are all you should need to adjust. I suspect you are describing the grinding you get when you are cross chained. I.e. big ring with either of the 2 biggest sprockets. Or inner ring with either if the 2 smallest sprockets? The cassette spacer must be placed on the spike side of the cassette as you have discovered otherwise the lock ring does not hold it securely to the freehub.

It’s not he cross chain as it happens with the largest chain ring and in the smallest sprocket. I know that there is some chordal action that’s is normal when on higher gears but what I’m having it’s about 20% more. I can feel the pedals vibrating. When on lighter gears it seems fine. Also when I’m on light gear but the trainer set a climb, than the problem is back. So, it seems that is not the gears adjustment (it looks perfect from the back) but the feeling when in high tension/torque.
It could be that the chain is not tight enough? I couldn’t find info on how to setup a chain length from scratch…
Thanks a lot for helping out