12 speed cassettes on direct drive trainers

re: “today’s direct-drive trainers will not work with bikes with less than 8 speeds on the cassette”

7 Speed Bike on Wheel-off Trainers:
A seven speed bike will probably work on a modern direct drive trainer. There’s a YouTube video showing the concept and the adjustment that is needed for a seven speed cassette versus what’s needed for an eight, nine or ten speed cassette. Those 8, 9 and 10 speed cassettes will go straight onto the 11 speed direct drive trainer with a simple adapter. For 7 speed use, you need to add a second spacer, 4 or 4.5 MM, and file a couple of small indents in the aluminum spacer. Our local bike shop provided a 4mm spacer for a couple of dollars and we used a 7 speed triple from the 90s on a 2014 Wahoo KICKR for months.Here’s a video that helped me:

Sorta correct. A modern 7 speed cassette might physically attach on the trainer’s freehub body, but it’s not going to shift well on SteveK’s vintage 6 speed drivetrain. It’s apples vs oranges.

Your suggestion would be apples to apples for someone who has a 7 speed drivetrain on a bike manufactured in the past 10 years, though.

some beginner questions:
11-speed cassette and 10-speed chain
I am running a 11-speed cassette on a wahoo trainer and ride a 10-speed bike with a 10-speed chain. The riding feeling is not very smooth - can I go ahead or do I need to change to a 10-speed cassette on the trainer?
shifting during training
Do I shift during training or what is the most recommended gear set-up during training? Should I use the biggest chain ring and a medium teeth at the back? What does expirienced riders recommend?
braking or stopping the trainer
I am struggling with braking - if I am not pedaling the wahoo is still rolling not like a fixie but the trainer is still turning - is this wanted or do I do something wrong?
ZWIFT and wahoo
after training - do I disconnect from ZWIFT and do a full log-out or do I only close the APP? Similar with the wahoo - only step off or fully unplug the trainer?

Sorry for my questions but sure YOUR answers will help me to become a good ZWIFTER.

Hi @Christian_Dietl

  1. if your bike is 10 speed than you should use a 10 speed cassette on the trainer. 11 speed had different spacing.

  2. I found small front ring is better and mid rear. But you can change gears if you need more power like going from 100w to 600w quickly.

  3. no problem just let it roll.

  4. Full -log out is always better, also turn your trainer off.

Hope this helps.

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Hi @Christian_Dietl

A 10 speed chain will not mesh well with an 11 speed cassette. It’s best to use the same cassette (number of speeds as well as the gear range) that’s on your bike for this exact reason.

Assuming you’re using a wheel-off Wahoo trainer: the large flywheel will continue to roll - that’s what gives you the smooth rolling feature. It’s best not to apply the rear brake - especially if your bike has hydraulic disc brakes. Applying the brakes without the brake rotor in place will close the gap between brake pads. Next time you try to put the wheel back in - the rotor may not fit.

That is correct. I was however responding to your statement that “today’s direct-drive trainers will not work with bikes with less than 8 speeds on the cassette,” to add the information that today’s direct-drive trainers will work with bikes with 7 speeds on the cassette.

Hi Shuji. I use my 12 speed mountainbike on a Taxc flux s smarttrainer. This is connected to a 12 speed 11-50" cassette where the first 8 rings match the range 11-28 teeth. Within those 8 first rings the trainer performe quite ok(I still reach quite a unrealistic high speed compared to real life). The last four rings 32-50 teeth have no function at all. No matter how steep the terrain is there are not enough resistance to make any use of them, both in free ride and erg mode. The cadence is way off also. Is this the way it is supposed to work, or could it be that something is wrong? Also does it matter wich gear I calibrate my trainer at?

Hi @Tommy_Roenningen
Some of that is expected relative to a road bike. Just as when you ride your mountain bike outside on flat pavement - your lowest gears will be too low to be practical, and when you’re going fast on the flats you’ll spin out your highest gear of 32x11.

First - I’d recommend calibrating your trainer using the Tacx app. Power readings can vary if you calibrate when it’s cold vs when it’s hot. Also - perhaps the cadence RPM’s will be improved?

Secondly - the level of resistance you feel is predicated on several variables - your age, height, weight, but most critically - your Functional Threshold Power number. If the FTP number is set too high - you’ll barely be able to move the pedals. If your FTP is too low - the trainer will not provide enough resistance. You can manually adjust this in the game app, in the Menu settings.

If you set the FTP high enough that your low climbing gears are usable - chances are your top gear will be too difficult. Your speed numbers will probably be unrealistic as well. As long as you’re not doing a race where bizarre numbers would skew the results, it’s probably not doing harm to anyone else.

Lastly - have you tried the off road routes where the increased rolling resistance makes better use of your mountain bike?. We are adding more off-road game features like steering that you might find fun. Be sure to select the Zwift mountain bike in your garage to use the steering feature.

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I came across aftermarket 12 speed cassette which is compatible with existing Shimano 11 speed spline. Maybe that might help preserve the existing Shimano 11 speed freehub for trainers using 12 speed drivetrains.

Interesting. I’ve never heard of this brand or product. Can’t speak to how well it may or may not shift with 12 speed SRAM or Campagnolo road drivetrains.

Cramming 12 cogs on the freehub body may leave very little clearance between the derailleur cage and the spokes of your wheel (if you’re mounting this on a bike). If mounting it to a trainer you may have similar clearance problems, depending on the trainer design. Proceed with caution.

I am 2 months into using their 11speed (11-28T) SLR cassette 205gm vs Ultegra 235gm. The cog engagement is near Ultegra but not as fast though it eventually worked.

I am looking at a Sensah Empire Pro 12 speed groupset that looked promising. Until I do, can’t say anything more about 12 speed trainer set ups.

Thanks for the reply Shuji.

Brand new to Zwift and have a question about cassettes and this thread seems on point. Tomorrow I am getting a new KICKR with attached 11-speed cassette. I had thought about dedicating an old road bike I have that I don’t ride anymore but it has a 7-speed rear cassette with 3-speed front cassette. From what I’ve read (the bike is an old Canondale from 2003) this isn’t going to work without a lot of mods and maybe not then. Yes I know I can get a different trainer that allows me to leave the wheel on but I wanted a direct drive. I can use my current Specialized Roubaix Comp with it’s 11-speed cassette just prefer a dedicated bike to use with the trainer. The old Canondale is not going to work is it?
-Bob

@Robert_Patton
The short answer is it depends on how old this 3x7 drivetrain is. If it was made in the past 10 years, it’ll probably work fine. If it’s 1980’s vintage, then probably no.

It’s from 2003. At worst, it just won’t change gears correctly, right? Can I hurt anything by giving it a try? I won’t damage the trainer/cassette I hope! I might just carefully try to set it up and see what happens. Not sure how easily it would be to get someone at Wahoo to talk to about this.

If 2003, you should be ok. Stack both a 1.8mm and a 1.0mm spacer behind the 7 speed cassette to take up the extra width on the freehub body.

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Little update. A sram nx 12 speed 11-50 cassette will fit straight onto trainer without using xdr freehub.

@Robert_Patton
As Shuji wrote, it’ll work. See the March 23 post above in this thread: 7 Speed Bike on Wheel-off Trainers:

A post was split to a new topic: Trainer Difficulty vs Gear Ratios

I ordered an XDR hub for my Tacx Flux so I could run my 12 Spd SRAM AXS group on it…6 months later I’m still waiting, they finally have them in stock and apparently it should arrive in June!? Garmin have taken over Tacx and the customer service leaves a lot to be desired here in Australia.