Stages or 4iiii?

Thinking about putting a left side crank PM on the MTB. Have never run one on the MTB before. Its for Shimano XT M8100. Any significant differences between the two? Also considered the Sigeyi but would have to replace all my chainrings and they take about 3 weeks to get.

Maybe stages have sorted it out but 4iiii is just so much more reliable in my experience. 4iiii’s are a little more compact and usually cheaper anyway.


I went 4iiii (for a dual sided) based off anecdotes from shops saying that Stages was unreliable (so much so that they stopped installing them). I’ve had no issues with it.

I run one of each on different bikes, no issues with either…so far :slightly_smiling_face:

Same here other than having to replace a battery cover door and O-ring on the Stages.

No issues with my Stages XT crank arm over the past year. I’ve yet to see a cal reading outside normal.

I’ve had a Stages Gen 3 for 3 years now and I had a few short dropout issues early on. But since I turned the ‘Gyroscope’ option on in the app I haven’t had any real issues. Never used a 4iiii though

4iiii never missed a beat for me. Highly recommend.


Whichever is available first, and cheaper?

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Only have experience with 4iii, but never had any problem over the last 3 years. (Except forgetting to change the battery)

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Replaced my Stages left side with 4iiii left side last year. Very happy with that decision.

I’ve had really good luck with Stages power meters for Shimano Ultegra crank arms. I got those on both my road bikes. Accurate, reliable, and easy to use and maintain.

Seems like a wash…both are in stock and about the same price. Thinking I like the 800 hr battery life on the 4iiii.

The 4iiii app allows you set an offset so you can match readings with other power meters eg your smart trainer. This is really handy for consistent numbers and makes the 4iiii the better buy imo.


I’ve also used both a Stages and two 4iiii left-side PMs (on road bikes), all ‘just worked’ and the numbers have always agreed.

The practical differences are tiny, I found, the 4iiiis weirdly takes longer to zero-offset but that’s a matter of seconds. As battery ran out on the Stages I’d start to see short power spikes in files (rescuable data), but when I’ve let 4iiiis battery run low the power reading just drifted up and up, not really rescuable data. The battery cover on the Stages is slightly easier to get on and off.

Stages customer service (UK) were very helpful when I contacted them for a new battery cover. I haven’t had to contact 4iiiis. If I was choosing again I’d be happy with either, and just go on price. The fact that they seem to have settled at the same price point probably tells us something!

What is this option?

My Stages gen2 has been pretty good but I had to learn a few tricks.

The best one was using fresh name brand batteries in retail packs. I had been buying the cheap 10 packs of 2nd tier batteries on Amazon and went through a patch of spotty performance. I even had a cheap pack of Energizers that were not great. Maybe they were fake? They were in oem packaging.

Since buying fresh retail Duracells or Energizers I’ve had no problems.

I have noticed that my o-ring is bone dry. I don’t ride in the rain so moisture hasn’t been an issue but I think a tiny bit of silicone grease would be a good idea.

I ended up ordering a 4iiii Precision 3 today…sounds like you can’t go wrong with either one.

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There’s a checkbox in the stages iPhone app for it. I think it says it uses marginally more battery but since I turned it on my already infrequent dropouts became much more rare.

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Interesting, I’ll check that out. I mostly see dropouts indoors which I have tracked to 2.4ghz WiFi interference. I switched all my devices to 5ghz and hardly ever see dropouts anymore.

Well that was easy…ordered yesterday and paid an extra $25 for one day shipping…installed and calibrated in 15 minutes. No clearance issues at all, the thing is tiny.