Stages Cycling shook up the power meter market in 2012 with the introduction of their left-side crank arm power meter. Unlike previous power meters at the time, the Stages measured left leg power only. This meant you simply swapped out your current crank arm for a new, power equipped one. It was also the first power meter to use both ANT+ and Bluetooth SMART wireless protocols. While Stages was first to the party with this type of power meter, 4iiii Innovations quickly followed suit, producing its own versions of a left-side crank arm power meter. While the power meters produced by these companies share many similarities…they are not without their differences. So we thought it would be helpful if we conducted a Stages vs 4iiii crank arm power meter comparison – and put these three power meters head-to-head!
Why Crank Arm Power Meters Are Popular
Left-side crank arm power meters have become one of the most popular power meters out. Here’s why:
- Affordable – Since you are just buying the left-side crank arm (instead of an entire crankset, new set of pedals, etc.), they are one of the more affordable power meters you can buy. In fact, 4iiii and Stages has certain models priced at $299. This makes them the most affordable direct force power meters available.
- Easy to install – This design allows for easy installation and swapping of the power meter between bikes. The power meter can be installed or moved between bikes in about 5-10 minutes.
- Light – They are extremely lightweight. These power meters only add about 10-20 grams (based on the model) to your bike.
It is important to note that a consideration with a left-side crank arm power meter is…well…just that. It’s left-side only. This means it takes your left leg power and doubles it to approximate total power. This is how all left-side power meters work. This type of power measurement is just fine for most folks, but some might prefer dual leg power measurement.
So if you’re okay with a left-only power meter and like things like affordability, ease of installation and lightweight (who doesn’t) – and of course have a compatible crankset, than a Stages or 4iiii might be right for you. Below, we briefly summarize these three companies and put the power meters head-to-head across several key considerations you’ll likely want to consider.
Power Meter Crank Arm Manufacturers
Stages Cycling got their start in the indoor fitness market, manufacturing power-equipped indoor cycling bikes. Starting in 2010, they began work on an outdoor version of their power meter and by 2012, they were producing what is now referred to as the Stages Cycling power meter.
The Stages power meter was the first power meter to use both ANT+ and Bluetooth SMART protocols, as well as Active Temperature Compensation, which works to keep the power meter accurate regardless of temperature changes.
The company recently launched their Stages generation 3 power meters which feature a stronger transmitter, among other refinements. Stages offers a range of models for road, track and MTB. Compatible cranksets include Shimano, Campagnolo, FSA, Cannondale, SRAM and Race Face. They also make carbon arms for select cranksets. Prices range from $299 to $849 (excluding dual-sided cranksets).
4iiii Innovations, maker of the PRECISION, is based in Alberta Canada and develops a range of sports performance technologies. The company entered the power meter market in late-2014, unveiling the PRECISION, the world’s lightest power meter.
Like the Stages, the 4iiii power meter is a left-side crank arm power meter that takes your left leg power and doubles it to approximate total power. 4iiii units feature ANT+ and Bluetooth SMART, are accurate to +/- 1.0% and run off of either a CR2032 or rechargeable battery, based on the version.
4iiii is on their 2nd generation of power meter. They offer both the PRECISION (CR2032). Unlike the Stages however, 4iiii power meters are only compatible with Shimano road and MTB cranksets. Prices range from $299 to $549 (excluding dual-sided cranksets).
Both the Stages and 4iiii left-side crank arms install the same way. You simply remove your current, left-side crank arm and replace it with your new, power-equipped version. Installation typically takes about 5-10 minutes for most models. Some models, such as the Stages Carbon power meters, require you to change out your spindle as well, and this adds an extra step to the process. But it is still a relatively basic process. It can be performed at home in your garage as long you have access to some allen keys and a torque wrench. Note that for Shimano models, you will also need a Shimano Crank Arm Cap Tool.
In general, crank arm-based power meters are one of the lightest power meters you can buy. This is because the added weight of the sensor that is bonded to the inside of the crank arm weighs practically nothing. 4iiii takes the win here as its sensor adds a mere 7.5-9 grams (based on the model) to your bike. But we have to admit, this is splitting hairs a bit. The Stages power meter only adds 20 grams – which is still very light. Since the weight is negligible for both of these power meters, you could also call this a tie.
Both the Stages and 4iiii crank arm power meters run off of 2032 coin cell batteries. This is a very common battery amongst power meter manufactures and for good reason. It’s relatively small, affordable, easy to source and provides good run time.
Stages gets the win with approximately 200 hours of run time per battery. This is compared to about 100 hours for the 4iiii. Considering the CR2032 battery is cheap and is easily changed, we don’t consider this a big win…but a win none-the-less.
Ability to Easily Change Batteries
Battery changes on these crank arms couldn’t be easier and it’s done the same way for both. You pop open a small black battery door on the sensor, remove the old battery and insert the new one. No special tools required. It’s a one-minute job.
Quick tip – you will find a small O-ring on located around the battery compartment. It serves to keep moisture out. So when changing batteries, make sure the O-ring is in place and is in good condition. In the event you lose or damage the battery door, no worries. We sell Stages replacement battery doors and 4iiii replacement battery doors.
All of these crank arm-based power meters transmit power and cadence data via both the ANT+ and Bluetooth SMART wireless protocols. This makes the power meters compatible with either your favorite head unit, smart phone or tablet. Quick note – some people have complained about dropouts with the Stages power meters when using ANT+.
It’s true the Stages Generation 2 power meters suffered from this in some specific situations. However this is no longer a concern. The Stages Generation 3 power meters features radio antennas that are 6x more powerful than the previous version. We’re yet to hear of a signal issue with the current generation Stages power meters.
We are going to call this one a tie as well. 4iiii claims an accuracy of +/- 1.0% and Stages +/- 1.5%. However, the 1.0% difference we are talking about here is minimal. In addition, it’s really hard to validate this differential. Third party tests have shown these power meters to track other, popular power meter models closely. Is it possible that the 4iiii is slightly more accurate…perhaps, but in the grand scheme of things, we don’t think this should be a deciding factor.
Active Temperature Compensation
As the temperature changes during your ride, the material that houses the tiny strain gauges within the power meter can expand and contract. As this material shifts, it can ever-so-slightly bend or torque the strain gauges. This can negatively impact the accuracy of the power meter. Enter active temperature compensation. This technology allows the power meter to adjust for changes in temperature during your ride, which helps keep the power meter accurate in all weather conditions. Both the Stages and 4iiii power meters features this technology – so all good here. Another tie.
Both crank arm power meters measure cadence, so this is a tie. In addition, they both do so using an accelerometer, which is an electronic device that is housed inside the power meter that measures the acceleration of the crank arm.
Both power meters require the user to perform a calibration (technically called a zero-offset) procedure before every ride. The process of zero-offsetting can be done via the power meter’s app or your head unit. It takes all of 15 seconds and ensures accurate power for your ride.
The 4iiii comes with a 3-year warranty, so it gets the win here. This compares to 1 year for Stages.
Stages Cycling takes a big win here and this is one of the biggest differences between these brands. The company makes crank arms that are compatible with Shimano, Campagnolo, FSA, Cannondale, SRAM, Race Face, Easton and Specialized cranksets. They offer carbon arms as well as versions for road, MTB and track. 4iiii on the other hand, only offers road and MTB crank arms for Shimano.
Smart Phone App Functionality
Both of these power meters feature Bluetooth SMART compatibility and also have dedicated cycling apps. The apps are free and are available for both iOS and Android. While there are definitely some differences in the apps – the 4iiii app is the only one that lets you record ride data – there are also similarities. For example, they all allow you to update firmware and conduct your pre-ride zero-offset. We’re calling this a tie as the there’s too much subjectivity to determine a clear winner.
Ok, so we saved the big one for last. We’re going to focus on Shimano versions here because that is one model sold by both companies. As you can see in the table below, across all models, pricing is basically the exact same – yep another tie! The only difference we see is on the new M9100 MTB left arm where 4iiii is priced at $474.99 and Stages is higher at $529.99. Other than that, both companies have price matched each other.
This table also highlights some differences regarding availability of certain models. When it comes to road, you can see that Stages offers right only crank arms, whereas 4iiii does not. However, 4iiii offers a R7000 Dual-sided crankset (a great value for a dual-sided road power meter), but Stages doesn’t. On the MTB side of things, you’ll see that only Stages offers right side units and dual-sided cranksets. 4iiii sticks to just left side MTB crank arms.
|4iiii Innovations||Stages Cycling|
|Road - Left Side|
|Road - Right Side|
|Road - Dual Sided|
|CX/Gravel - Left Side|
|CX/Gravel - Right Side|
|MTB - Left Side|
|MTB - Right Side|
|MTB - Dual Side|
As you can see, and as we mentioned at the outset, these power meters share many similarities (installation, battery, ability to change batteries, communication protocol, cadence detection, calibration, etc.). But there are some differences as well. Most notably crankset compatibility (Stages is compatible across a wider range of cranksets) and warranty (4iiii has a longer, 3-year warranty).
We’ve personally owned and trained on all of these power meters and they’ve been great. It really comes down to what’s important to you – and quite frankly, what equipment you’re currently running. If you have a Shimano crankset and want to save some money, the 4iiii is probably a great choice. If you have a SRAM or FSA crankset for example, you’re looking at Stages. We are pretty confident that regardless of your choice, you’ll enjoy it and will be a stronger cyclist for training with power!