plgcp

I recently got a direct drive smart trainer and both my wife and I are interested in using it, but my bike is Shimano 105 10-speed while hers is Shimano 105 11-speed. It’s quite a hassle to swap the cassettes each time we switch the bikes. Before I try it and risk any damage, is it possible to leave either the 10s or 11s cassette on the trainer and use both bikes on it (each having a chain intended for the respective number of speeds). If so, which cassette is best to use? If it matters, it’s not a problem to avoid shifting into the last gear with the 11s derailleur. I assume it’s a question of cog spacing and whether the indexing would be completely off for the bike using the “wrong" cassette. I read some of the Sheldon Brown articles for the answer but I still came away confused.
Thanks

alcjphil

I don't see how it would be possible to use the same cassette for any 2 bikes that have shifters with different numbers of gears. Each time you shift with either bike, the rear derailleur moves the chain sideways a set distance and the distance the derailleur moves is different for 11 speeds than it is for 10 speeds. Using a cassette with a different number of cogs than the number of shift positions you have will move the rear derailleur the wrong distance in order for your chain to mesh smoothly after your shift. The more shifts, the greater the mismatch. Unless you change the shifter, which is more difficult than exchanging your cassette, you can't make this work.

plgcp

Thanks, that's sort of what I figured, but I did read that in some instances the cog spacing is/was the same between speeds (might have been for older 7-9 speeds or something), so was hopeful.

124Spider

My bike has an Ultegra 11-speed rear cassette, while my wife's bike has a SRAM 10-speed. Our smart trainer is a Wahoo Kickr with an 11-speed cassette. It really isn't a problem to use it with the 10-speed bike.

FWIW

veganbikes

Go 11 speed or get a second trainer or just swap cassettes with the Park Tool Chain Pliers and their long handled cassette tool it is super easy and doesn't take a ton of time.

shoota 

My buddy is borrowing my 10 speed wheel to use with his 11s bike on his trainer. It works ok. He has about five or six gears in the middle of the cassette that work just fine but the low and top end don't work well. Most people don't need that kind of range on a trainer anyway. You're not going to hurt anything by trying.

TrojanHorse

I did the cassette swap thing for a while and then just bought a second hand kickr core for my wife (so we can ride together). It's a mild pain but certainly not difficult, about a 5 min. chore. One thought - perhaps get a second cassette carrier and just swap that out rather than the cassette.

You could probably use a 11 speed cassette with your bike in erg mode, but shifting will be crappy and noisy if you're just riding around on it.

redlude97

If you are planning on using it in ERG mode then you can just leave it on a cog that works well for each respective bike. If you are planning on using it on say zwift where you need to shift, it will never work well

Sy Reene

Even with Zwift, you could in theory set trainer difficult to 0% (OFF). I think this makes the trainer work like the entire course is flat though, so you'd likely find pretty boring. At least you'd have 2 gears though.. ie. Front small vs Large chainring.

plgcp

Thanks for all the replies. We have been using both bikes on the 11-speed cassette with the 10-speed bike using ERG mode in Zwift. This has worked great but discourages non-workouts in Zwift.

I am curious about the above suggestion though relating to a "second cassette carrier". Googling has only taught me that cassettes typically have some number of the largest cogs fixed together (called the "carrier"(?) ), but I haven't been able to find anything about any after-market components that seem helpful. If this comment is suggesting there's a way I can sort of fix together all the cogs/spacers to facilitate removing and replacing without having to replace each cog and spacer one at a time I would be very interested in more info.

TrojanHorse

Argh, I should have called it a freehub sorry about that. This is a wahoo campy freehub, they also sell spare shimano versions. You'd still have to take the lock ring off the front of the cassette but then instead of removing the cassette from the freehub, you just unscrew the nut holding the freehub on and remove that, swap for the other one and off you go. It really just prevents having to look for the dinky spline and get your fingers all greasy while you're lining up all 10 or 11 cogs. And spacers.