This post is being continually updated as problems and fixes arrive. Please scroll to the bottom for updates.

Background: 4iiii (pronounced “Four-eye”) is not a household name for cyclists. They make a number of different cycling and running products, but seem to focus mainly on sensors (heart rate, speed, cadence, and now power). I first found out about them when DC Rainmaker posted about their power meter prototype. His initial findings were positive, and they were shooting for a price point of $400. Because of all this I decided to pony up for a pre-order. At that point the estimated shipping date was Q4 2014.

What they were claiming was a power meter that looked much like Stages, but for roughly half the cost. A unique aspect was that you installed it yourself on your crankarm, using an installation kit they would send you. Additionally, this could be installed on either crankarm, and in fact on both crankarms if you bought two units. Therefore you could start out with single-leg power, and then later upgrade to full left and right power measurement. Finally, the unit would broadcast over Bluetooth LE and over ANT+.

However, just as DC Rainmaker predicted, 4iiii was unable to hit their initial Q4 estimate. Moreover, they ran into some regulatory issues with shipping the glue. Their workaround was to have you mail them your crankarm, and they would then install the unit for you, and then mail it back to you. My understanding is that they’re still working on having the user do the installation, though it’s unclear at exactly what point they will make this switch. The price is still $400, and all the details listed above are still true.

Installation: Installation is trivial. After they mail you back your crankarm with power meter installed, you simply remove your old crankarm and install the new one. It took me less than five minutes. You’ll need some allen keys and a little five dollar Shimano tool.

Next up is pairing the unit. I initially had been using my phone (Moto X, Andoid v4.4) as a bike computer, using either Wahoo Fitness or Strava. Once I got the Precision installed I opened up Wahoo Fitness and found the power meter (using Bluetooth). Unfortunately, Wahoo would not receive any data from the Precision. I had similar experiences with Strava. I then switched to my wife’s iPhone 5s, and this time Wahoo Fitness found the Precision and received data. It seems to me that the issue is with the Android apps. I contacted 4iiii about the issue, and they spent a lot of time with me trying to solve it. 4iiii does have their own Android (and iOS) app which indeed sees Precision and receives power data, but it doesn’t do any recording. In the end nothing helped, and I simply had to abandon using it on Android.

After the issues with using my phone to communicate with Precision, I broke down and ordered a Garmin Edge 500. I’m happy to report that everything works perfectly over ANT+. My guess is that most people who want to purchase a power meter already have some sort of ANT+ head unit. If you do, then you should have no worries about using Precision. Moreover if you’re using an iPhone and plan to use Bluetooth, I would also not worry. However, if you’re an Android user and do not own an ANT+ head unit, I would be a little wary of ordering. I assume that eventually the apps and 4iiii will get on the same page and everything will work. I will continue to test as these apps (and the power meter firmware) get updated. I’ll post future updates here.

Usage: Since it’s a power meter, it transmits both watts (power) and cadence to your head unit. It is up to your head unit or some other sensor to handle speed.

Ideally I would compare Precision to another power meter in many different settings. Unfortunately I don’t have another power meter! Therefore I’ll leave that to DC Rainmaker. In my limited experience with it (~2 weeks) I haven’t run into any problems (see my 8/6/2015 update below for a re-analysis of accuracy). If you’re the technical sort then you can check out this thread on Slowtwitch. The engineer who designed Precision (Keith Wakeham) pops in and talks a bit about the accuracy, and how it compares to other power meters on the market. In short, he believes Precision is highly accurate. I haven’t seen anything to make me believe otherwise.

Customer Service: I’ve (unfortunately) had the opportunity to spend a good deal of time with 4iiii customer service. This stemmed from being unable to get the unit to communicate with my phone (as discussed above). Even though we didn’t really get the issue fixed I still came away happy with their service. I communicated with them through both email and through telephone. Responses were prompt, and I was told that if they couldn’t get the problem fixed then they would send me a new unit. Once we realized that the fault was not with the power meter, this no longer became relevant.

As one final note, when 4iiii shipped the power meter out to me they sent it overnight FedEx from Canada, all for free. This was highly unexpected and extremely nice. I was out on a ride when I got an email saying it had shipped, and the next morning by 10am I had it in my hands. I’m sure this couldn’t have been cheap, and even though a difference of a couple days doesn’t really make that much of a difference, it feels big to eager customers.

Closing Remarks: So, the obvious question is, should you buy a 4iiii Precision power meter? First off, I would suggest waiting until DC Rainmaker posts a more in-depth review (Edit: He has released his review! In it he examines accuracy in far more detail than I do, and finds that overall things are looking pretty good. He concludes by saying that “4iiii Precision is a solid left-only option.” Head on over for the full review.)

If you’re happy with left-only power and you don’t need the power meter within the next couple weeks, I would highly recommend Precision. Besides the bluetooth issues I’m not seeing any problems. It’s very small, and at least according to the main engineer it’s significantly more accurate than Stages, while also undercutting Stages by at least $300 (at least a 40% discount).

One touted feature of Precision is that you’ll be able to convert to dual-sided power measurement by simply purchasing another Precision and installing it on the other crankarm. Their point is that you can try out single-leg measurement, and if you eventually decide you need more accuracy then you can upgrade. However I’m not so convinced by this logic. For $800 (the price of two Precision units) you’re right up against other dual-leg power meters (Pioneer, Vector, PowerTap). If testing ends up showing that Precision is significantly more accurate than those existing power meter then of course the Precision is a great deal. But in my eyes the biggest draw of Precision is that you can start training with power for just $400. There’s simply nothing else like that on the market right now. I’ve wanted a power meter for at least a year now, but dropping almost $1000 on one seemed crazy to me. For that money I could buy myself another (used) bike. But $400 drew me in, and thus far I’m glad that it did.


12/8/2015: DC Rainmaker has released his review, and he recommends the Precision and finds no serious accuracy problems. Here is the link to his review. On my end everything has been great! When firmware updates are released I’ll continue to talk about the impact they have. I haven’t had any problems in the last few months, and battery life has indeed increased with the recent firmware updates.

11/25/2015: 4iiii released a firmware update this week. As with the previous updates they’re claiming another increase in battery life (claimed 25% improvement). I’m back to riding regularly, so I’ll keep reporting back. However in my opinion one of the best new features is that the 4iiii app (Android and iOS) now shows the remaining battery percentage! Previously there was no way to know how much battery you had left, so that’s now been remedied. Besides that, everything has been running as it should for me. I still find calibration on an Edge 500 to be a bit slow (and it sometimes fails), but I’m not sure where the fault lies with that. More and more I’m just happy with how it’s performing. No major problems coming up, battery life is now respectable, and they’re pushing out firmware updates. I’m going to ride with this for another month or so, and then come back and update my review a bit with my revised thoughts. Until then, ride on!

10/16/2015: Update to the last update! I counted up my hours, and I have 56.5 hours of riding recorded on the last battery. Note that that does not include commute time. I don’t record my commutes, but I would estimate (very) roughly about 20 hours of commuting. So it looks like this last battery lasted roughly 75 hours; a big improvement! I’m back to training now, so my usage will be more regular, and if that number is correct then I should be updating again in about 2-3 months. I’ll be back!

10/9/2015: Two small updates. First is that my battery finally died. If you’ve been reading the previous updates then you know that before the firmware update the battery was only getting about 20-25 hours of riding before it would die. I haven’t had time yet to add up my hours, but I will do so very soon. My time includes commuting, which I don’t record, so I can’t get an exact value. However I definitely got more than 25 hours, but I would guess less than 50.

Second, DC Rainmaker has put up a new post where he (very briefly) rides a dual-sided 4iiii prototype. His impressions are positive, and he doesn’t see any obvious flaws. When he pressed them about when this dual-sided power meter would be available, they could only say “early 2016.” However, based on how inaccurate their initial ship dates were, I wouldn’t put much faith in this estimate.

Besides that I’ve had no problems lately, though admittedly I’ve been riding much less this past month. Base training is kicking off for me on Monday, so I’ll be putting in more miles then. So keep checking back for updates!

9/11/2015: I spoke with customer service at 4iiii to find out where they’re at with new orders. They said that if you order a Precision today, you should expect to have it in your hands in about 2-3 weeks. As I briefly addressed in my previous update, it seems like they’re basically caught up with their backlog of orders. This is definitely good news for new customers. They also said that for the foreseeable future they will ask customers to ship their cranks in, and 4iiii will do the installation. In my opinion this is better than customer install. You’re essentially getting a Stages power meter, but at a much cheaper price.

I’ve been watching all the new power meters coming out, and for the most part I feel like my statement about there being nothing else out there like Precision is still true. Prices for other power meters (that are currently shipping) are still at least $600. The only other power meter that seems really appealing is the Power2Max. Their entry-level power meter is only $610, which includes a full chainset (FSA Gossamer). The downside is that if you want a nicer crank then the prices go up significantly. So if you currently have something like Ultegra or DuraAce and want the equivalent from Power2Max, then you need to tack on several hundred more dollars. 4iiii on the other hand doesn’t care what crank you have (so long as it’s not carbon!)

Finally, I haven’t posted any updates lately about battery life. This is because I took about a month off training after my racing season wrapped up. I’ll be starting up my base training next week, so I’ll post some updates soon about how that’s looking.

8/6/2015: In my review I purposely avoided the topic of accuracy because I didn’t have any other power meters to compare the Precision to. That is still the case, but after riding with it for almost five months now, I feel qualified to make some preliminary statements about accuracy. In all my time of riding, only once have I gotten power numbers that seemed wrong (it lasted about a minute in the middle of a ride, and then reset itself back to normal). My power numbers have progressed as you would expect them to progress with training, and always seem very believable. Is it possible that the numbers are always off by 10 watts, or that there are weird spikes that I miss? Absolutely. But for someone who wants to train by power, and is only interested in measuring against their past performance, I’m not seeing any problems with the Precision. I trust the power data, and never once have I looked at some interval and thought, “I bet those numbers are wrong.” My personal guess is that the accuracy is excellent.

Finally, a word about purchasing Precision. For a long time 4iiii was way behind on fulfilling orders. On their “Friday Files” page they post weekly updates, including showing their orders sent vs received vs fulfilled. I’ve posted the July 31st graph below. As you can see, they’re mostly caught up. A few months back if you ordered a Precision you could have expected to wait months to receive it. That no longer seems to be true. Currently Clever Training is projecting that new orders will be fulfilled in September, which seems reasonable.

7/17/2015: Firmware update released! I’ll be flashing it and begin testing it out starting tomorrow. They don’t list a changelog, but they do mention that the firmware should “significantly reduce battery drain” and also “also improves the zero offset measurements, giving you more precise readings during your ride.” Battery drain will take a few weeks to test, since on the old firmware I was getting between 20 and 25 hours, which is roughly three to four weeks of riding for me. Previously I was swapping the battery around the 20 hour mark to avoid it dying in the middle of a ride, but with this new firmware upgrade I’ll keep it going until it dies. Check back for updates in the coming weeks!

6/30/2015: I went back and tried Strava and Wahoo Fitness again, since both apps have received updates. Unfortunately there were no changes, so neither communicates with the Precision.

6/17/2015: It’s been almost a month since my last update, and I’m glad to announce that these few weeks have been problem-free! I proactively changed my battery at around 20 hours of use to avoid it potentially dieing on me during an important ride. Still no firmware update from 4iiii, so I’ll update again once that appears.

5/28/2015: Things have been a little wonky with the battery swap, but seem to be working fine now. As I mentioned on the 5/20, the battery swap initially seemed to get Precision working again. However on a race day it decided to stop talking to my Garmin; great timing! When I got home I took out the battery, reinserted it, and again restored factory calibration values. Since then I’ve ridden twice and everything has gone just fine.

I realize that reading these updates may make it seem like the power meter is constantly giving me problems. That’s not really true. I’ve now had Precision for about 1.5 months. In that time there have only been 3 or 4 rides where I had a problem, and for the most part those were fixed pretty easily. Obviously zero problems would be preferable, but I’m willing to wait out some growing pains.

5/20/2015: After putting about 25 hours on Precision (all problem-free) I was on a ride and stopped to recalibrate on my Garmin. It refused to recalibrate, and so I simply finished the ride without power. Someone online had mentioned that other people had battery issues at around the 20 to 30 hour mark. So I replaced the battery, and my Garmin then saw and calibrated it. Unfortunately on the next ride the Garmin still wasn’t receiving data. Long story short, after replacing the battery I needed to go into the 4iiii app (Android or iOS) and reset and save the factory calibration values. After that everything seems to be working fine. I haven’t gone on a full ride yet to test it, but riding around my parking lot it delivered consistent and realistic power values.

Finally, I emailed 4iiii about the battery issue. They said that it is a known issue, and they’re working on fixing it in the next firmware update. They estimated a few weeks for the update. They also said that the reducing battery drain also was reducing power accuracy. So obviously they’re trying to fix the battery drain issue without also compromising power accuracy. I’ll update again when that firmware update comes out. Until then, you can find the correct batteries on Amazon for very cheap. I bought some extra and are changing them as needed.