4iiii Acquires STAC Performance

You beat me to posting this :slight_smile:

I think this is a great partnership IMO. Both companies are excellent and make reliable and accurate devices, so together can most likely make some great products. I am excited to see what the next year holds for 4iiiis


LOL, I caught the email from @tariqhali and had to share right away :stuck_out_tongue:

I agree that this seems like a great composition of knowledge and products. It will be interesting to see the progression of the STAC products with what I assume is greater resources from the 4iiii brand.

I suspect there will be some refinement of the current trainers. And who knows, maybe they will be working on a wheel off version with similar tech. I envision a direct-drive unit with a dedicated aluminum flywheel (to replace the basic wheel), but has their strain gauge power measurement and the smart control all in one.

I am excited for both companies.


I agree. They need to acquire to defend their market, with everything that is happening right now…

4iiiis and STAC are now more Canadian than Molson’s :canada:


From DCRainmaker’s blog post:

“The company didn’t clarify in the announcement terms if STAC would add any extra vowels to their name post-acquisition.”

Maybe next week we will read that STAC has changed their name to STAAAAC



The STAC sure looks like a school project. Engineers, function over form at its finest. It may be my next trainer though given how quiet it is.

I think we will see the current trainers “cleaned up” with better design and elimination of the tinker toy look.

I also expect to see a wheel-off direct-drive trainer at some point. Their resistance unit with a large aluminum flywheel (to replace the bike’s regular wheel) would be a great way to leverage their silent resistance, and improve the feel with an appropriate flywheel inertia.

Here is some deeper info from Ray.

The holy grail of trainers now is a true direct-drive at a reasonable cost. Only Tacx Neo is direct-drive, no transmission to spin up a small flywheel (and we all know how troublesome these transmissions have been, on Wahoo Kickr and Tacx Flux). Could that be done with the STAC concept? It’s a neat load unit, but it does not do inertia like a Neo, so it still would need a flywheel…

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I am sure they have something in development. What exactly? I am not sure. I don’t think they will go direct drive because I think they like the lightness of their unit, which allows for easy travel and setup at races for warmups. They may try to tweak their unit so that you don’t have to use wheel weights to get that road like feel and you can just take on and off your bike with ease. That would be perfect. I hope that they will also address the downhill spin outs on Zwift at the same time.

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Something, I hope.

A lot of new bikes these days are carbon rim and through axle. Two things which mean I can’t mount my new bike on the Halcyon I have here. They have to move to a direct drive model to simplify things. Even then this means they’re only coming up to speed with an already established market.

I made no secret of pointing out the the industrial design, finicky setup, the clunky weights, the alloy rim requirement, plus the on-bike experience being… well… different. Which wasn’t received well by Stac nor owners… but… I’m not a glossy magazine here to sell anything, just give my 2c. And that was my 2c.

They’ve obviously got something up their sleeve to combat these blockers. I’m keeping a close eye on this for something good.


I think your reviews are worth a bit more than 2c @GPLama


…And using the Covid19 pandemic as cover 4iiii have withdrawn all support for Stac Zero products beyond the 12 month warranty!

I get only really well with the Halcyon which suits my purpose nicely, not least because it’s compatible with my wife’s 6 speed tourer, and both of my retro 7 speed road bikes, and I even rather like its ‘industrial’ design. In the two years that I have owned it there have been three failures. Just outside the warranty period it bricked itself during a firmware update and Stac Zero/4iiii were fantastic with their support and managed to restart the update to give me the 2006 firmware which is excellent and gave me up to 10% resistance on hills. Full marks 10/10 A+++ etc.

Then three weeks ago one of the linear actuators that move the magnets seized in a fairly open position and made the unit unusable with perhaps 200W at 130 cadence. I contacted Stac Zero Support only to get an e-mail to say that support was withdrawn and that the support address wasn’t monitored. Then contacted 4iiii who just said that the promised Fliiiight upgrade package for the Stac Zero still isn’t available. Anyway those nice people at Stac had put the Actuonix OEM part number on the actuator and being in the UK I sourced one from RS Components for delivery next day (approx. £100). These can be sourced over the pond for less, but if the UK post office gets their hands on it and charges an admin fee for import duty all bets are off on how much that would cost! One of the mounting eyes was thicker than the original, and I couldn’t use the original circlipped pin, but the supplied bolt and Niloc nut worked well, and the Halcyon was up and running again. Three weeks later I’m on the trainer thinking how well it was working, when I feel the resistance randomly varying again, and bingo the other actuator fails - this time close to the wheel so still able to offer meaningful resistance (240W at 90 cadence).

I find it odd that these actuators should fail within three weeks of each other (after two years and 3,500 miles) so have contacted support at Actuonix to see what they think. Should I hear from Actuonix I will record their response here. It seems those of us with Halcyons have been abandoned by 4iiii, and hopefully recording my experience here will prove helpful to others.



It turns out that the motors in the Actuonix linear actuators have a service life of 125 hours. Mine failed at over 200 hours. (3500m at 17mph)

Actuonix were not aware of this application. They were very helpful and offered me a very generous one off deal on up to nine actuators. As a result there are five of them winging their way to me from Western Canada making up three sets with two sets spare or another six years at current usage. My son has told me that linear actuators are a bit like that!


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125hrs, That’s all??? Hmm not so stoked on my Halcyon anymore. What a stupid mistake on STAC’s part to specify such a short-life part.

Mine probably managed just over 200 hours, but yeah it’s a fair point!

I wonder what the Fliiiight uses to move the magnets…

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125hrs?!? How did that ever pass an MTBF assessment? Brutal.

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You assume there was an MTBF assessment.

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I’ve been on mine for 2 years, and a quick check says I’ve been on the trainer for 75 hours since May… so even granting that I’ve been more consistent on the trainer this year over 2018/2019, I am a mite worried. I still have the original STAC Zero resistance unit if/when I have a problem, but I sure have gotten spoiled by the app controlling resistance for me… :laughing:

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Yeah, a seemingly silly assumption seeing as they put it out the door that way. :confused: