Newbie: Indoor Trainer Question

Complete Newbie here (which will probably be evident by the following question):

I just bought a Saris H3 Direct Drive smart trainer. It says I need an 8, 9, 10, or 11 cassette. My intention is to only use the indoor trainer with the bike I’m purchasing for it. Let’s say I have an 11 cassette on my trainer, can I use a 7 speed bike with it? Would making any modifications make it possible (i.e. 11 speed chain)? I guess my simple mind was thinking if I took off the back tire, I could just attach the frame to whatever cassette I choose, I just wouldn’t be able to use all 11 gears if I had a 7 speed bike? Thanks for any help you can give me!

Overly broad, but mixing the gearing of a bike with different cassette gearing is not recommended. Chain width and cassette spacing changes depending on the exact versions you compare, and can lead to less than good performance.

This all gets more complex and confusing when you compare very specific examples (10 vs 11) can work if you are using ERG mode only, which really only needs one gear running between the bike chain and trainer cassette. That doesn’t work well at all if you are trying to use “simulation” mode in something like Zwift, and you want to shift gears like is expected.

So, in short, mixing is not recommended, but can be done in specific instances if you know exactly what is being mixed.

Edit to add, if you are aiming to use a 7-speed bike, you are likely best to get an 8-speed cassette. I don’t remember the chain widths for sure, but think those should be largely compatible. You would hopefully have full function, with just one less gear to access.


But… If you still need to buy the bike and the cassette for the trainer… Just buy a matching cassette for the trainer. So for an 11 speed bike, just buy the same cassette for your trainer.

If there is an 11 speed cassette on the trainer, good reason for an 11 speed bike :wink:

Yeah, I was just trying to be cheap and I’m noticing a lot of cheap bikes are 21 speeds. :slight_smile:

In that case, an extra 7 speed cassette will set you back max 20 dollar. That way you can use different modes of the trainer instead of 1 lucky gear

Unfortunately this trainer says it doesn’t work with a 7 speed cassette.

Ah, sorry, missed that…