ERG only - Workouts yey, ramp test nay

I got my first smart trainer (Kickr Core) yesterday and put my only bike on it, a 12-speed mountain bike on my 11-speed trainer. As I expected this became a problem with tests that require “sim mode”.

Sufferfest is the best product I have tested so far and I would really like to continue using it but as it is now I can only do the workouts because of the ERG-only mode. FTP-testing would be nice to have.

Is there some workaround here that I’m not seeing? Even supoptimal are welcome.

I guess I could use another product for testing purposes, any recommendations?

I guess the problem comes from the shifting not being compatible right? I’m not sure if I’m being over simplistic here, but, wouldn’t a 12s freehub + casette solve the problem?


Yes, I think this will work but right now I’m looking for a software solution.

What is SIM mode? do you mean level mode for doing Full Frontal.

What cassette have you fitted to the Kickr Core?

perhaps you’re better off asking the minions directly in this case… Otherwise I think that trying to hack it, will result in kind of tainted test results.

Yes the problem is it’s a mechanical issue not software.

The closest “hack” would be to use ERG mode but effectively use the intensity settings kind of like gears. This wil only really work if you have a keyboard within reach so you can easily hit the up/down arrows. Also, it will be difficult to make sudden big changes as it’ll move in 1% steps of your power settings.

Definitely a hack and not a great solution. But it’s the only way I can think of to get some kind of virtual level mode. The real answer is as others have mentioned which is to get a 12 speed hub and cassette in the turbo

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It’s a 11-speed Shimano 12-25 CS-R7000. I got a 12-speed Eagle NX on the bike.

I’ve talked with three local bike firms regarding what cassette to buy and they all came to different conclusions. One said 12-speed wasn’t possible. One said i needed a XD/XDR freehub to get a Eagle NX-working. One said I could use the standard hub and fit a NX-cassette on it. No one can guarentee that their solution will work and refuses money back if it doesn’t.

So at the moment I’m looking for a quick fix before blindly droppin 100-200 dollars more into the trainer.

Nothing is wrong with the sufferfest software! It’s actually the most stable one I’ve tested so far :slight_smile:

This might actually work for the second part of the half monty. I could give it a try.

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From a quick Google it’s an XD freehub you’d need. XDR is the road version. But an XDR hub with one of the road cassettes may also work as I “think” the actual spacing of the sprockets is the same (but don’t quote me!)

I’d recommend contacting wahoo support as they should be able to confirm which part you need. Plus obviously you’d need a cassette :slight_smile:

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Actually looks like it’s the same hub they do for both standards just with a spacer to switch between XD and XDR

(My work laptop just crashed hence I have time to play on Google lol)

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Try folks at bike24 if you’re in europe or Chainreactioncycles

Hey. Just spotted this. @ThomasAR

So I do this stuff all the time. Swapping the MTB with its 12sp gearing on to (a Kickr or a Neo in my case) trainer. I don’t imagine the Core is any different.

When I’m not feeling like getting my hands dirty I just swap the bike on, if it’s my hardtail I have to take the brake caliper off (2mins). Tweak the gears if they need tweaked and off I go. 12 into 11 works fine for me … I’m not using the whole cassette anyway. And actually if I’m using ERG then I just use the best chain line and leave the gears alone. For non ERG I use Levels0-9 and make sure I have half a dozen if the gears working. It the difference is so small between 11 and 12 it just works fine.

When I can be bothered swapping the cassette I have one normal mount 12sp cassette that I keep for trainer use. It fits on the normal freehub - no need to change to XD. It cost me £70’a couple of years ago - was their lowest tech ‘NX’ level.
Benefit is it doesn’t wear out the nice SRAM cassettes that are expensive while Riding the trainer too.
They’ve been available for a couple of years now.
Then you have all gears and level mode to play with.

This is all do’able at little cost relatively speaking. Though looking at prices now cassette prices have gone up along with everything else. Maybe find a Sunrace one.

Pm me if you want any direct advice on installs or anything.


No freehub swap needed. The cheapest 12sp Sram 12sp cassette that they designed for ‘shimano’ freehubs.

Having said that when I bought mine they were £70. Looks like they’re about £100 now !!!
Still saves freebie swapping (unless of course (OP) you want to permanently stick to XD cassettes for ever on the trainer).

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SRAM Eagle NX cassettes have an 11T small cog and were designed to fit a standard 9/10/11Speed Shimano freehub, if you have a chain whip and cassette lockring tool you will be able to swap the cassette from your bike to the trainer. BUT you will need to check it doesn’t foul with the trainer because the largest sprockets on SRAM 12speed sit inboard of the freehub (this is how SRAM managed to squeeze in another sprocket into the same space). If it does foul your only solution is an 11spd drivetrain for your MTB or a spare bike to use on the trainer.

I would avoid using the same chain on two different cassettes unless you are closely monitoring chain wear, chains and cassettes wear in together and using either with a less or more worn one, rapidly accelerates wear.

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Have to say I’ve never had an issue with that. I only have one bike so it switches between my road wheel and KICKR with zero shifting issues.

Sad to say in recent years it’s my KICKR cassette that has had more wear than my road wheel :frowning:

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yup thats why it works so well

re the chain thing - thats a perm problem unless its a perm bike on the trainer — i use the sames bikes out as i do in, so i just suck up that issue if it occurs but fair point aye — its a possiblr additional cost of running the same bike twice (but i akntnswapping chains and cassettes unless i really want to - eg a 12/11 tbing where im changing the primary bike immriding)

its all choice

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