Question about STAC Halcyon and Sim mode

My trainer is a Halcyon and I love it, mainly because of silence.

I got it and decided that i liked TR better than Zwift because i dont care about zwift social things and i rather have a good structured plan. So for that reason I have never use Sim mode, only ERG.

Tomorrow I will attempt to do the 20 minute FTP test.
If I understand it correctly, that specific test (and the 8 min test) are done on SIM mode and Im not sure if i need to adjust something on the trainer for that, or TR will do that for me.

Then I know there are the Halcyon tweaks on the STAC “app” but not sure what would be the “ideal” number for better road feel.

Anyway, i would appreciate any help.

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The info and vids here are helpful.

The trainer will switch to Resistance mode (not Simulation). You can adjust the overall effort 2 ways.

  1. Shifting to harder or easier gears.
  2. Adjusting the Resistance percentage up or down. For many trainers 20-40% is a good starting point. You will be able to experiment in the early block of the test and alter the setting if needed. The app will keep that setting when it switches for the main test block.
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Thanks for the links.
I though Sim and Resistant were the same. I guess is not.

Ill probably have to do a dry run today or tomorrow and make sure i know what im doing.

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Sim is a replication of a route, like Zwift or another video replay based app (from GPS data), that aims to replicate road grade dynamically.

Resistance is just setting a single resistance force based on a percentage of the max trainer resistance.

And yes, a dry run (maybe with a deliberately lowered Workout Intensity setting to make it “easy”) can be useful to see how it really works.

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No wonder why you are a leader on the forums!
Great information and always willing to help the uninformed!


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You’re welcome. Happy to help whenever I can. :smiley:

I have Halcyon as well. There is no need to change anything for the FTP test. Just start with relatively hard gear, but not the hardest so that you don’t need to shift too much when it changes to the resistance mode. That’s probably what you are probably doing anyway.


So it changes automatically to resistance mode?

I tried yesterday, but I was using the laptop and not cellphone as I normally do.

There was a drop down to select mode… I set to resistance, not sure if I need to leave that alone…

Yes, leave it alone for the test. It will switch automatically.

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I use the Halcyon too and love it since I have kids. Haven’t figured out resistance mode though so I just ride Erg. Tried doing the TR Free Ride once and just couldn’t get it to work. Guessing there’s something super basic I’m missing.

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That’s a great idea! Fiddle around with the gearing so you know ahead of time what gearing combination gets you into the power range you can achieve. You know…make sure you can hold a comfortable cadence in that 400W zone you crank out.

When I first tried this I found out the resistance slider bar didn’t do anything. It was a TR bug specific to my trainer. Easy to work around but not the sort of thing you want to find out in the beginning of a 20 minute test. You don’t want to be worrying about that stuff during your test. Just crush it and then puke. That’s all you should have on your mind.


Man. its a shame what 4iiii did to the trainer. It looks better now, but at what price.
I hope the next version is better than the fliiiight. So much potential!

anyway, this is the first time i try resistance mode. So ill let you know how did it go
The few minutes I tested yesterday felt fine…
So will see later today.

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One of the things to keep in mind with the STAC/4iiii is that it needs a fast wheel speed to maintain its inertia and avoid the resistance death spiral. As the wheel speed drops, the resistance really clamps down. Something to play with in resistance mode, but an absolute killer in erg mode. I find that I run mine in 53-11 to 53-13 almost always.

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Even on resistance mode?

On my test yesterday I was using the next to smallest on the back and 53 up front (the same I would normally use) and noticed that the power was way higher that i would wanted at that point going at about 90 rpms. Resistance was set to 33%.
I changed gears to my go to gear for longer rides (right on the middle of the back) and power felt to what should gave been.

Any thoughs?

Honestly, on TR I always used it in erg mode, and Sim mode in Zwift. I do know that near the end of a ramp in erg, the cliff comes pretty sharply.

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Oh…that i know…its like a wall!
Ive been doing the ramp test, but decided to do a 20 minute this time around and see which one feels better for me,.

Do you guys use the “road feel” weights that come with the halcyon? I always have, curious if you notice a difference.

I always do too…not know the difference.

I used them, but they don’t stay in place very well on my wheel. I got tired constantly adjusting them and haven’t them for a long time. They certainly make a difference and I prefer the feel with them, but it’s ok without them when using relatively hard gear.


I really like how you can adjust Halcyon with the app. You can adjust calibration to make it match your powermeter and play with delay and ramp rate. They also still have a good customer service and I have always found an answer for any issues I’ve had.