4iiii Precision (Gen2) Power Meter Review – Zwift Gear Test

The Precision 4iiii began life in 2014, aiming to upset the powermeter market with one of the lowest priced, lightest weight power meters out there. Coming in at around £200 cheaper than a Stages power meter, that is quite a saving. The question is, do you pay for the £200 saving in other ways?

4iiii Precision Power Meter Review – Zwift Gear Test

4iiii Precision

4iiii Precision casing

Let’s deal with the pricing of the 4iiii Precision straight away. The original intention for the Precision was to be a crank mounted, user installable, powermeter. This approach has currently been put on the back burner, and instead 4iiii offer two services; you buy the power meter and crank from them direct, or send in your original crank to 4iiii who mount the powermeter for you in the factory and send your swanky upgraded kit back after approx 2 weeks

Using your own kit is one direct saving to the customer straight away, if you send your crank in, you don’t end up with a random spare part hanging around your garage, then is reflected in the price.

An install to your crank, assuming you’ve a compatible crank, costs £321.99 (ex vat). You can opt to “go pro” if you like, by spending £602.99 (ex vat) to go for a dual-sided powermeter sending in your crank and crankset, BUT that is currently only available if you’ve got a Shimano Dura-Ace 9000 series – currently.

4iiii precision

4iiii Precision options

You can however still opt to buy the “whole enchilada” straight from 4iiii themselves, which does have the option of not leaving you without a crank during the factory-fitting process.

Your options if you want to buy a pre-installed 4iiii precision are limited to only to Shimano cranks, priced from £349 for the 105 crank, through to £499 for a new Dura-Ace crank

4iiii precision

Device Design

4iiii Precision

For this review, I’ll be focusing on the single sided, crank mounted 4iiii precision, here matching my Ultegra Di2 system. From exterior face of the crank there is not even the inclusion of a logo/transfer to show that you are using a 4iiii powermeter.

4iiii Precision
In many ways there is almost very little to say about the 4iiii Precision, from design perspective when you actually do turn the unit around.

4iiii Precision
It’s a very small sensor box. Looking for all the world like a standard speed or cadence sensor, but is bonded directly onto the crank

4iiii Precision
Some people will prefer the more discrete, having less fan fair, and thus less to advertise if someone is looking to steal your bike when it is chained up outside.
Inside we’ve the usual coin cell beneath a small plastic door, with the “made in Canada” displayed front and centre on the inside

4iiii Precision
4iiii take a nod to the end user by also including a spare coin cell in the box, which I personally feel is a great little touch

4iiii Precision


Weight: 9 grams

Data accuracy: +/- 1% error margin

Communications : ANT+, Bluetooth Smart head

Battery life: 100+ hours on 2032 coin cell battery (let’s not forget that 4iiii throws in a spare, which is a really nice touch!)

Battery status indicator: Alert at 15% battery power in app (no external indicators)


The manual for the 4iiii Precision can be found HERE

Using the Device

4iiii Precision

Being crank mounted, there is a modicum of work required to install onto your bike. But for most people who are keen enough on cycling to want a powermeter, the install shouldn’t be troublesome!

Step 1 – find and secure bike – identify crank to be changed

4iiii Precision
Step 2 – remove Shimano plastic cover from existing crank

4iiii Precision
Step 3 – loosen bolts and remove pedals and old crank

4iiii Precision
Step 4 – apply new 4iiii Precision crank to shaft

4iiii Precision
It’s probably worth while noting that 4iiii have taken a lot of care over the pod placement, to ensure bike frame clearance, against the widest number of manufacturers.

4iiii Precision
Plus also easy user access for battery changes etc. Once all done with the mechanics, you need to install the 4iiii app which will then allow you to update the latest powermeter firmware

4iiii Precision
With 4iiii Precision brain updated, you’re ready to take the unit for a spin and compare it with any other powermeters you have lying around

4iiii Precision

How does it Zwift? – Zwift Gear Test

Well first things first, it’s worth while highlighting that that 4iiii Precision, has a 1% accuracy on the leg it is measuring the power from. In aleft sided setup like this, many people are concerned about leg imbalances, and the issue of “just doubling the power”, which would magnify any imbalance between your two legs. HOWEVER with the 4iiii Precision firmware you can account for any balance, to give a true reading

4iiii Precision
Etixx QS team are happy with the firmware based adjustments to account for any left/right discrepancies, so use the 4iiii Precision as their main training device without concerns of issues about under/over reporting power, when calibrated correctly for the rider. As a comparison, I opted to use another single sided meter, the PowerTap C1  4iiii Precision
Remembering that power meters are ideally tested in three, I loaded up the Wahoo KICKR SNAP, and took things out for a sprint on Zwift.

4iiii Precision
So let’s take a look at the graphs which came out from a few sprints during the Team EXperimental group ride:

4iiii Precision

All three powermeters track very nicely together. The PowerTap C1, tracked fractionally higher during the tail down from the sprints, compared to the 4iiii Precision. Other than that, the 4iiii Precision appears to justify it’s name.


4iiii Precision

One of the biggest issues with racing on Zwift is getting accurate power representation. Zwift Power exists to allow users who don’t have power meters on their bikes, or classic turbos to get spinning right from the install – BUT – it’s not a perfect system, and can have issues.

A power meter is a terrific upgrade for serious racing or training on Zwift – if you can afford it. Over the last few years the price of power meters has tumbled, bringing them into a price bracket where more people can consider them. The 4iiii is definitely a budget friendly option (comparatively speaking) but doesn’t show any signs of being a budget quality power meter. In fact, to my mind, the factory install option, where you don’t end up with excess kit lying around the house – for a cheaper price and a 2 week turn around seems like a good way of trimming the costs

So if you are thinking about a new powermeter for this winter’s Zwifting. Definitely check out this Canadian offering!

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  • Nice review. Just a quick question: Can you use the KICKR Snap (or any smart turbo) plus a separate powermeter both synced to Zwift? So you get the gradient specific resistance changes on the smart turbo still, but power data sent to Zwift from your powermeter instead?

    • John

      @Tempo: Yes, at the initial Zwift “Paired Devices” screen there are separate options for power source and controllable trainer (or you can use the same for both).