Help - cassette type and size

Hello, just bought an Elite Zumo, downloaded Zwift etc - nearly ready to start except one thing - the cassette.

I was totally oblivious to the choices of cassette sizes and teeth until now, I’d love your feedback / assistance.

Q1. 9,10 or 11 speed?
Q2. 32, 34 or 36T?
Q3. Does it matter if I buy an entry level £20 or so, what would be the benefit of spending more money for the same brand? As I’m new to Zwift, I just want to get running rather than spend lots
Q4. What about my Rear derailleur on the bike? The cassette on my back wheel is 9-speed. If I added a 10 or 11 speed onto the smart trainer, wouldn’t I need to adjust the derailleur every time I wanted to use my bike as a normal bike?

Excuse my lack of knowledge - total newb.
I was close to buying the Shimano CS-HG81 10 Speed Cassette 11-36T but worried about buying the wrong thing.

Q1: 9 speed since your bike is 9 speed.
Q2: try to get the same as your current bike but this is not a big deal.
Q3: The entry level ones may not shift as smooth as the higher end ones. But at some point the shifting stay constant end the weight decrease.

Do you have a road or MTB?

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Hi Ewan,

I had in September the same competition and I decide me to the same System than on my road bike was installed. You now that you can‘t mix 9,10 or 11 systems because the chain must be different for example 9 chain on an 11 casste don’t work and the chain always slip through and find no hold. . Another thing is, that in Zwift you have many climbs to solve, so it‘s usual to choose a mountain setup. I had luck and my road bike has an 11 system 50-34 on front and 11-32 with 11 gears on rear and for me it works great. So I can set Zwift on trainer difficulty to 50% and don‘t need the 0% setting. Maybe my reports helps you find the Right solution for you.

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Hello Gerrie,
For my sins, I’m a single track MTB’er so it’s a hard tail mountain bike I have with a 9-spd SRAM cassette on the rear.

On Zwift I’ll be road cycling so I do want to set it up as smooth as possible, however, the SRAM shifters I have are grip shift, they’re quite clunky when cycling normally.

Now I know to stick with 9-spd and I’ll stick with SRAM, I take it the only choices are entry level vs expensive?

Given the MTB setup, I get the feeling it would be a waste spending any more than £30-ish on a cassette?


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I agree don’t spend to much on a cassette for the trainer. My rule is get the one second lowest price.

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So it looks like this is what I need, just one more question…
How do I know If the 9spd SRAM I currently own on my bike wheel is 11-32?
Will all 9-speed cassettes (Shimano/SRAM) be 11-32?

11-32 is the number of teeth on the small and big “gears” of the cassette.

One way to know is to just count the teeth. or it will be stamped. on the gears.


But it wont be a big deal if you get a 11-32 vs a 11-36, your shifting will still work you will only have bigger jumps between gears. I would suggest 11-32 because you have a MTB on the trainer so you wont need the big gears at the back.

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Thank you, I’m far more confident I’m buying the correct item now (and I can get it delivered tomorrow for only £20 on Prime).




Although this post is about a month old now… I just wanted to thank you for it…

I’m in the same situation you was and ended up just confused by the choices!

How have you gotten on with a MTB on the Zumo and Zwift in general?

If you put the Zwift resistance up to 100% you will need a 36T on the cassette to get up big climbs and still be able to spin, or just put it to 50% and put any cassette you like on the back, you could move the resistance up and down until you get the feel you want when you are in the easiest gear for going up hill. You still have to put out the watts to move up hill so it is better to do it at a comfortable cadence and not ruin you knees. I think Zwift resistance is more like giving you a massive cassette on the back if you drop it to 50%.