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4iiii Precision Power Meter (LEFT Side Shimano): Details // Data Review

4iiii Precision Power Meter (LEFT Side Shimano): Details // Data Review


A power meter review in under 5 minutes? Let’s give it a shot Today I am diving into the 4iiis precision Power Meter It’s also known as the Precision 2.0 or the Precision 2.0 3D. The specs of what I have here and on the bike are… [Reading the Tech Details listed on screen above] With the accompanying app from 4iiis you can… [See App Details Listed Above on screen] And when performing a zero offset on this power meter it will return a helpful code, not just or something random. If everything is OK it will return 10 for the left side. If you have left and right for the dual sided it will return 10 10. Other codes are listed here [on screen] i’ll put links below but it’s kinda handy to know things are OK after you perform a zero offset. Time Check? We are still looking good!
Over to here quickly to DCRainmaker’s Analysis Tool where we can compare multiple power meters as an overlay and see how they stack up. My outside ride here, 2hrs up against the Assioma Uno. I split my DUO to an UNO so we had left pedal and left crank recording Fair decent ride here. We will dive into the data for this climb here. 306w vs 309w. Now the way this records power is differently to the pedal. Every different power meter will record differently. So you will get slight variances and what we are seeing here in those slight variances is the spikes. So in Purple, the 4iiis is a little spikier and the dips are a little lower You can see here, but not too bad overall. Another little climb, for some steady state stuff here and here. 254w vs 253w very close, but again a little spikier. One short sharp acceleration (not quite a sprint) here at the end and the 4iiis gets the jump on the Assioma. It is the UNO, it does say DUO on screen, that’s just what I’ve got them labelled as. It is the single sided power meter on both and they record just a little differently and that could be due to number of different factors A longer sprint is probably going to be a better test for this It wasn’t too bad once things came into alignment they tracked ok and I was already done by then. A standard Llama lab test, a little short though as there is nothing that is going to effect this with temperature It does have active temperature compensation so it should be good there. Looking at the Llama Lab test. So we have the Assioma UNO, Tacx Neo and the 4iiis Dura Ace left only. Hard to compare directly with the Neo as the Neo is both left and right total power, the other two power meters are left only and doubled. We have 229w vs 224w vs 223w. Depending on how you want to read the tea leaves today, which one you think should read higher or lower depending on where things are at. It’s close, but we can see the spiky one. Again it’s the 4iiis and it is spiking down quite a bit For example i pick one data point here. It reads 177w for that specific point in time there that is raw, un-smoothed. Why it reads 177? I am pretty sure I was not doing 177 on the pedals at that time. Close though. Very close. Into the sprint, this time the Assioma gets the jump. It’s been flipped. It’s just the nature of things with single sided and the recording intervals. And once time goes on 3 seconds they all line up here. It’s close, no cigar. If you want killer accurate sprint power, get yourself a Left-right power meter as close to the pedals as possible. The crank or the spider. You know what I’m talking about. It’s close. Just riding along: 136w vs 136w vs 138w. Cool, Happy Days. Flipping over to the overs and unders. I had one hell of a drop out session there at the back half of the 450w section. Other than that ll looking pretty good, given it’s Left and doubled. It’s going to be a little wonkier. Still a little spikier. Here – Just short. Over here when I do drop. And there is an actual drop. Both power meters on the left do drop. The 4iiis again is a little spikier. And then just some riding along. Some short hard effort there at the end. 155w vs 152w vs 152w. All looking pretty good. Again some red spikes there from the 4iiis. Final time check: We’re good! And it’s time to wrap this one up for today. So in summary, pretty much what i expect from a single sided Shimano left hand power meter. The numbers outside against the UNO – Fantastic! Indoors – not too bad! But i really would like to see that data smoothed a little bit so we don’t see that data number jumping, even when we have on 3 sec smoothing. So there we have it. My take on the single sided, 4iiis Shimano based Precision Power Meter Links below for more details on this. And as always remember to hit that thumbs up to subscribe and support what I am up to Thanks for watching.

30 comments on “4iiii Precision Power Meter (LEFT Side Shimano): Details // Data Review

  1. Spikier four eyed fish. Competing with Stages I'm guessing. Similar product and price so I think you would be better off with Stages

  2. thanks!!! hopefully the piggybank is full in march, ready to hit the roads again with a 4iiiiiiiiiiiii powermeter on the bike

  3. For an absolute amateur such as me, it seems pretty ok. Nice, as I was lucky and got a very good deal on it and has been using it this summer.

  4. For a long term 4iiii single sided user it's reassuring to see this one, from a data accuracy point of view, thanks. As you mention the calibration codes, one thing I will mention is that I have suffered the error 20 in motion fault that a number of others report (if the internet is anything to go by?!), whereby the bike is stock still but won't zero and you may start to see other weird and wonderful behaviour, such as monster high power readings etc.

    This has happened to two separate units for me but once I'd been clear about trying 4iiii's standard troubleshoot unsuccessfully both they and my UK distributor, Hargrove's, were great in authorising and dispatching replacements. There are some work arounds via the power of Google to get this fixed nowadays but I'm hoping 4iiii have finally fixed it at source this time around…

    It emphasises the need to always buy these big purchases from a distributor you trust though. I still doubt the reliability of all power meters in the long term, perhaps unfairly due to the power of the grapevine suggesting issues across a wide range of types and manufacturers.

    Other than the issue above I have been delighted with the 4iiii. It's so simple to fit or switch to different (Shimano in my case) bikes and it's always provided consistent numbers that have helped achieve big gains.

  5. Hey Shane, since the last windows 10 update that was pushed my bluetooth connection went from 100% rock solid to a 3-5 second drop out every 30 minutes or so. I remember Zwift sending an email about it, but haven't heard anything since. Is there any word on changes?

  6. They have great customer support, for sure. I have had to send my left side 4iiii for warranty. After few months, my 4iiii started show half of power without any reasons. No crash, no water inside, done software update, zero offset, new battery etc https://analyze.dcrainmaker.com/?fbclid=IwAR0OP8Za6W9dMOusYxQNTM5S8kUdB4g2Zo2ZOTS4ijr2JeyZGPomATjzvSI#/public/c682a7af-cc3d-49fa-5a9e-219b5ae7ced3

  7. One question: I have this 4iiii power meter and the Magene Gravet 2 smart trainer. Which one should I use as a power data source? 4iiii should be a bit more accurate but it's only one side power reading. Thanks.

  8. Missed the protocol the power figures were being recorded over – ANT+ power rises/drops on a standard channel period, shifted by +/- 1 second are going to be difficult to separate in any meaningful way. If a PM is ahead or behind in those cases ? Meh, probably more indicative of sampling than sensor placement.

  9. Had this for a while and really liked it. I had an issue with the battery cap breaking the tab on the actual PM part, but 4iii repaired it free of charge. Had to get rid of it recently, as I changed my steed to a Gravel bike with a Praxis Alba crankset 🙁

    Trying to work out the best way to get power on that bike now.

  10. What's the difference between this and the Specialized Power Cranks (Left only upgrade kit) which is also based on 4iiii Precision?

  11. Bought one of these early summer, and the readings are so super spiky, it actually makes it quite difficult to use, even with 3 second smoothing. I certainly never use it indoors. Kinda wish I'd gone for Stages now…

  12. After making the mistake of purchasing and then suffering with the Powerbeats product, I found a deal on the 4iiii left side crank (Ultegra) and I couldn't be happier. Like Wahoo, they seem to make a product that simply works! For most riders of my ability (real and imagined) the minor differences between perfection (or your standard) is of little value but reliability and consistency rules the day. As always, thank you for producing both entertaining and informative videos.

  13. Great review, thanks Shane. Have you had a look at the dual-sided version? I assume it suffers from the classic Shimano crank right-side disease. Or have 4iiii applied some witchcraft to it?

  14. Shane, This is a very timely video. I owned an identical left leg 4iiii power meter which was amazingly accurate and tracked my NEO perfectly… Until it just stopped measuring torque. Cadence? no problem at all, but just Zero watts always. It could not be fixed and was out of 12 month warranty 🙁

    Problem is, my friends 4iiii also just stopped measuring torque too. Cadence was fine again. Both of our 4iiii's failed between 18-24 months of use. Do a search on the web and you will see our story repeated many, many, many times. I am convinced there is something inherently wrong with the 4iiii strain gauge or bonding cement. While initially ok, consistently fails within 2 years.

    I don't want to throw shade on what is an extremely accurate PM product but I warn potential buyers to research the long term ownership information that is out there.

  15. Got a 4iiii on my indoor bike. Power data is very close to my Assioma Duo pedals. As mentioned by others the 4iiii company gives great service. Recommended by me if you want a low cost accurate power meter.

  16. Another great and helpful review Shane! Could I trouble you for a unrelated question. On zwift why can't I see average wattage for segments like I can out in the real world? I am using a bike without a power meter and a wahoo kickr.

  17. Over here in the EU the 105 and Ultegra models are often found for 300 euros or under at various webshops, making this a great option imo. (I have the 105 version for a year now, no issues whatsoever)

  18. Been using this one for a while, more than happy with it. It's not ridiculously over generous with the power readings, and certainly doesn't steal as much power as Strava!

  19. I've been stumped, but for me I cant figure out why left handed power meters dont report accurately for me. I've tried 4 stages and assioma left handed power pedals and against my tacx neo and quarqs left handed always reads low, 40w at 300w range.

  20. Hi Shane… I have this 4iiii PM on my Ultegra Carbon bike… and the Garmin 530.. and I used it all summer but, I am embarrassed to say I have no clue how to properly benefit from a power meter… Can you maybe do a session on Power Meters for beginners? Including what parameters to set up on the Garmin… for example, I used the instant power reading at first, then I switched to the 3s reading… I have no idea what I'm doing… what all this means. Can you also point me to some good reading material if possible? I'm just 60 year old amateur rider… not a strong rider…. I do ride 80-120km hilly rides 2-3 times a week in the summer, but my average speed ends up around 19-22 km/h…. Had some extra money to blow so I bought myself a power meter… LOL.

  21. Hey Shane. I’m in the market for a smart trainer… Leaning towards the Wahoo Snap… does it matter if it has a power meter or not if I already have the 4iiii on my bike?

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