Adding a power meter to your bike is one of the smartest investments you can make in your cycling journey. But before you buy, it’s important to make sure you’re getting the perfect fit. From choosing between a pre-installed crank or a factory install, to checking your frame’s clearance, there are a few quick things to verify. We’ve put together this complete buying guide to walk you through the process, ensuring you can order with confidence and hit the road faster.

What Is a 4iiii Power Meter and How Does It Work?

A 4iiii power meter is a lightweight cycling training tool that attaches directly to your crank arm to precisely measure the power you generate while riding. It works by utilizing our patented 3D Strain Gauge technology to capture the exact lateral bend, pull, and twist of the crank as you pedal. This tri-axial measurement delivers highly accurate, repeatable power data (tested to a ±1% accuracy tolerance) that is instantly transmitted to your preferred head unit, smartwatch, or phone via ANT+ and Bluetooth.

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BUYING OPTIONS

Ride Ready vs. Factory Install - Which Is Right for You?

The first major decision when buying a 4iiii power meter is choosing how you want it delivered. We offer two distinct purchasing paths tailored to your budget, your timeline, and the gear you already own. Here is how to choose the right fit for your bike.

The “Ride Ready” Option: Pre-Installed and Ready to Swap

If you want the quickest path to riding with power, a Ride Ready power meter is your best choice. With this option, we send you a brand-new left crank arm or complete crankset with the 4iiii power meter already installed and ready to ride.

• Who it is for — Riders who want zero downtime and an immediate, plug-and-play solution.
• The compatibility — Ride Ready meters are available in both single-sided (left arm only) and dual-sided configurations. We stock a large lineup of brand-new Shimano cranks, including popular road, gravel and MTB models like 105, Ultegra, Dura-Ace, XT, XTR and GRX.
• The biggest benefit — It is incredibly straightforward. Simply remove your old crank, install your new Ride Ready crank, pair it to your head unit, and you are ready to ride. As a bonus, you get to keep your original crank as a spare!

The “Factory Install” Option: Add Power to Your Existing Crank

Don’t want to buy a brand-new crankset when the one currently on your bike works perfectly fine? The Factory Install option allows you to mail us your existing crank, and our technicians will custom install the power meter directly onto it at our facility.

• Who it is for — Riders looking for the most cost-effective way to train with power, or those riding non-Shimano drivetrains.
• How it works — Once you place your order and verify your frame clearance, you simply ship your compatible crank arm or full crankset to 4iiii. We perform a precision installation, test it to our rigorous ±1% accuracy standard, and ship it right back to you.
• The biggest benefit — Factory Install is highly affordable and environmentally friendly since you are upgrading the parts you already own. It also opens up power meter compatibility to a much wider range of alloy and carbon cranksets beyond the standard Shimano ecosystem.

What Is the 4iiii Factory Install Process And How Long Does It Take?

A 4iiii Factory Install is a custom service where we install a PRECISION 3+ or PRECISION 3+ PRO Power Meter directly onto your existing crank. The manufacturing process, from the time your crank arrives at our facility to the time it ships back out, takes approximately 7 to 10 business days. Here is exactly how the mail-in process works:

Step 1 - Clearance Check
Before purchasing, you must confirm there is enough clearance between your crank arm and your bike frame for the power meter pod to fit. Use our Frame Clearance Check Guide to confirm compatibility. You will be required to send a photo of a successful clearance check before shipping your crank. If you are ever unsure, just contact the 4iiii support team for help before ordering!

Step 2 - Purchase and Shipping
Choose your Factory Installed power meter directly from the Factory Install page on our website. At checkout, you will select your return shipping options and rates. Once your purchase is complete, we will email you a Ship Kit that includes a pre-paid FedEx shipping label and safe packaging instructions.

• Pro Tip: Take close note of the required package size in the Ship Kit! Extra charges may apply if you use an unnecessarily large box.

• International Note: Customers outside of Canada and the US may be required to pay taxes and duties (VAT) applied by their country’s import laws, which 4iiii is unable to estimate in advance.

Step 3 - Manufacturing and Installation
Once your crank arrives, our technicians attach the power meter pod using the exact same tools, techniques, and strict quality checks used on all brand-new 4iiii products. This custom manufacturing and calibration process takes about 7-10 business days. We will provide a tracking link so you can follow your crank’s progress through the factory.

Step 4 - Shipping Back and Reinstallation
As soon as your crank passes our rigorous ±1% accuracy testing, we ship it right back to you using the shipping method you selected at checkout. As soon as it arrives, simply reinstall it on your bike, perform a quick zero offset, and you are ready to train with power.

Where Can I Buy 4iiii Power Meters?

You can purchase 4iiii power meters directly from our website with worldwide shipping, or locally through our extensive global network of authorized dealers and bike shops.

Buy Directly Online: We ship worldwide directly from 4iiii.com! Whether you are picking up a brand-new Ride Ready crankset or placing an order for a Factory Install, buying direct is fast, secure, and gives you access to our complete inventory of single and dual-sided power meters.

Find a Local Authorized Dealer: Prefer to support your local bike shop or want in-person advice regarding crank compatibility? We partner with top-tier cycling retailers and distributors around the globe.

• In North America: Use the 4iiii Dealer Locator on our website to instantly map the authorized storefront closest to you.
• Outside North America: Scroll down on the Dealer Locator page to view our dedicated international partners and distributors.

Note: If there isn’t a local partner in your specific region, don’t worry—you can always order directly through 4iiii.com to take advantage of our global shipping options.

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SINGLE VS. DUAL POWER

Should I Choose a Single-Sided or Dual-Sided Power Meter?

A single-sided power meter is perfect for most cyclists looking for an affordable, lightweight way to track their efforts, while a dual-sided power meter is ideal for advanced riders who want independent left/right balance and comprehensive pedal stroke metrics.

This is the most common question new buyers ask. Both will make you a faster, smarter rider, but the right choice comes down to the level of data you crave:

• Single-Sided (PRECISION 3+): Measures the power generated by your left leg and doubles it to estimate your total power. It is highly accurate, incredibly lightweight, more affordable, and is the industry standard for millions of cyclists worldwide.
• Dual-Sided (PRECISION 3+ PRO): Features pods on both the left and right crank arms to measure each leg independently. It provides true total power, left/right balance data, and advanced cycling dynamics like pedal smoothness and torque effectiveness to help you perfect your pedal stroke.

Want a deeper dive? Check out our complete breakdown by reading our blog:
Single-Sided vs. Dual-Sided Power: Which Should You Choose?

Can I Upgrade from a Single-Sided PRECISION 3+ to a Dual PRECISION 3+ PRO Later?

Yes, you can easily upgrade your existing left-sided PRECISION 3+ to a dual-sided PRECISION 3+ PRO by sending us your right-side crank arm for a Factory Installation.

If you start with a single-sided meter and decide you want more data later, we have you covered. PRECISION 3+ PRO Factory Install upgrades are currently available in Canada/World, USA, UK, Benelux, and Germany.

Important Note for older PRECISION 3 owners: If you currently ride an older PRECISION 3 (the model without Apple Find My™), you will need to mail in both your left and right crank arms. We must factory-upgrade your left-side pod to the new 3+ firmware to ensure it pairs seamlessly with your new right-side pod. If you already own a PRECISION 3+, you only need to send the right side!

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COMPATIBILITY

Is My Bike Compatible with a 4iiii Power Meter?

Confirming compatibility is a two-step process and both steps matter.

Step 1 - Check crank compatibility
The first step is confirming your bike has a compatible crank. Use the 4iiii Crank Compatibility Finder at 4iiii.com/crank-finder/ to check your specific model.

Step 2 - Check frame clearance
The second step is confirming there is enough clearance between your crank arm and your frame for the power meter pod. 4iiii power meters require roughly 8mm of clearance between the inside of your left crank arm and the frame. Download the Frame Clearance Check Guide and follow the instructions before ordering.

Note: If you skip the clearance check and your power meter contacts your frame after installation, you will need to return it and order a Factory Install instead - where 4iiii can customize the pod placement to fit your specific bike.

What Makes a Crank Compatible with a 4iiii Power Meter?

Not every crank makes the compatibility list, and there are specific engineering reasons why. Here’s what 4iiii looks at:

• Crank material — For 4iiii power meters to achieve ±1% accuracy, the crank material must respond consistently throughout the life of the crank. Certain carbon cranks can change structure over time, making them incompatible.
• Crank shape — The power meter requires a smooth, flat surface with enough length and width to accommodate the pod.
• Product popularity — The compatible crank list is also based on market demand. 4iiii requires sufficient interest and demand before investing in validation testing for a new crank.

4iiii is continuously working to expand the compatibility list and update it on the website as new options are confirmed. If your crank is not currently on the list, it’s worth checking back.

Which Cranks Are Compatible with 4iiii Power Meters?

4iiii power meters are compatible with a massive range of road, gravel, and mountain bike cranksets. Our Ride Ready models seamlessly replace most Shimano Hollowtech II cranks, while our Factory Install service supports a wide variety of brands beyond the Shimano ecosystem.

Here is how compatibility breaks down based on the purchase option you choose:

Factory Install Compatibility
The Factory Install service is our most versatile option and is the perfect choice for riders who do not use a standard Shimano crankset. Because we install the power meter pod directly onto your existing equipment, it is compatible with a wide variety of alloy and carbon cranks. To find out if your specific exact make and model is eligible, simply search for it using our interactive 4iiii Crank Finder.

Ride Ready Compatibility
Our Ride Ready power meters come pre-installed on brand-new Shimano cranks, making them a plug-and-play upgrade for most existing Shimano drivetrains.

• Shimano Road Compatibility — Ride Ready road meters are available for Shimano 105, Ultegra, and Dura-Ace. Because many older and current Shimano cranksets share the same Hollowtech II technology, you can easily swap between component tiers (e.g., upgrading a 105 drivetrain with a Dura-Ace power meter)-just make sure you order your exact crank length.
• Shimano Gravel (GRX) Compatibility — We fully support Shimano’s dedicated gravel groupset with Ride Ready GRX options. However, because GRX cranks have a wider “Q-factor” (stance width) to accommodate larger gravel tires, you should never mix a road crank arm with a gravel crank arm. If your bike has a GRX drive-side crank, your power meter must also be GRX to keep your pedal stance perfectly symmetrical.
• Shimano MTB Compatibility — Mountain bike setups are slightly stricter. Road and mountain cranks cannot be interchanged. Additionally, if you ride Shimano XTR, your Ride Ready power meter must be matched to an equivalent XTR model.
• Non-Shimano Drivetrains — If you don’t currently use a Shimano crankset but want the immediate convenience of a Ride Ready option, you can still make the switch! You will simply need to change your bottom bracket to a Shimano-compatible one-a quick upgrade your local bike shop can easily help with.

Always Check Frame Clearance: Whether you choose a new Ride Ready crank or mail in your own for a Factory Install, both options require adequate space between your crank arm and your bike frame for the power meter pod to safely clear the chainstay. Before placing any order, you must always use our Frame Clearance Check Guide to verify your specific bike is ready for power.

My Crank Isn’t on the 4iiii Compatibility List - Are There Any Alternatives?

Yes! If your specific older or lower-tier Shimano crankset isn’t officially supported, you can often still ride with power by swapping in a cross-compatible left-side crank arm. Many Shimano cranksets share the same Hollowtech II design, so you can easily mix and match different component tiers.

Here is how you can use Shimano’s cross-compatibility to your advantage to ride with power, even if your current crank isn’t on the approved list:

• The Hollowtech II Advantage — Many entry-level or older Shimano groupsets use the exact same Hollowtech II spindle interface as modern 105, Ultegra, and Dura-Ace cranks. This means you can often purchase a modern Ride Ready left-side power meter and seamlessly attach it to your older drive-side crank.
• Match Your Crank Length — The golden rule when mixing and matching crank arms is to ensure the lengths are identical. If your current drive-side crank is 172.5mm, your new cross-compatible left crank arm must also be exactly 172.5mm.
• Road vs. Gravel (GRX) — While splines may match, be cautious about mixing road cranks (like 105) with gravel cranks (like GRX). They have different Q-factors (stance widths), so it is best to stick to road-to-road or gravel-to-gravel swaps.

Here are the closest compatible Ride Ready alternatives for common unsupported Shimano models:

Road:

Incompatible Crank	Closest Compatible Option
Dura-Ace 7900 Series and newer	Dura-Ace 9100 or R9200
Ultegra 6600 Series and newer	Ultegra R8000 or R8100
105 5600 Series and newer	105 R7000 or R7100
Tiagra R4700/R4600 and newer	105 R7000 or R7100
Sora R3500 / R3000 and newer	105 R7000 or R7100
Shimano RS510/RS500 and newer	105 R7000 or R7100

Mountain:

Incompatible Crank	Closest Compatible Option
SLX M7100/M7000	XT M8100
Deore M6100/M5100	XT M8100
Shimano MT900/MT700/MT500	XT M8100

Gravel:

Incompatible Crank	Closest Compatible Option
GRX RX600/RX400	GRX RX810/820

Once you’ve identified the right crank, use the 4iiii Crank Finder to check current stock, perform a clearance check, and confirm the correct length.

How Do I Find My Crank Model and Length?

You can easily find your exact crank model and length stamped on the inside face of the crank arm, right next to where the pedal attaches.

Look closely near the pedal threads on the inside of your existing crank. You will see a stamped model number (such as FC-R8100 for Shimano Ultegra) and a number indicating the exact length in millimetres-most commonly 170mm, 172.5mm, or 175mm. Because your new power meter must match your current right-side crank length perfectly to maintain your biomechanics, it is critical to confirm this number before ordering a Ride Ready unit.

Can 4iiii Install on Any Crank Length?

Yes, while most standard road and mountain bike cranks fall between 160mm and 180mm, our technicians can manually calibrate a Factory Install power meter to fit almost any reasonable crank length.

If you ride an exceptionally short or long crank arm that falls outside the standard 160-180mm range, we can still help you train with power. Simply contact the 4iiii support team before placing your Factory Install order so we can confirm the custom calibration details for your specific setup.

Does My Bike Have Enough Clearance for a 4iiii Power Meter?

To safely install a 4iiii power meter, your bike needs a gap of roughly 8mm (about the thickness of an 8mm hex wrench) between the inside of your left crank arm and your frame’s chainstay.

Checking your frame clearance is the single most important step before buying-and it’s easy to do at home. Simply download our Frame Clearance Check Guide and follow the step-by-step instructions to measure the gap on your specific bike.

• The 5.5mm Advantage — One of the standout design features of the PRECISION 3+ and PRECISION 3+ PRO is their ultra-slim 5.5mm pod profile. This exceptionally low profile makes them compatible with more bikes than ever before, easily clearing the wider, dropped chainstays found on modern aero and gravel frames that traditionally ruled out crank-based power meters.
• Always Verify — Because frame geometries and bottom bracket widths vary drastically between bike brands and sizes, clearance is never guaranteed based on the bike’s make alone. You must always confirm your specific frame’s clearance manually before placing an order.

Are 4iiii Power Meters ANT+ and Bluetooth Compatible?

Yes, all 4iiii power meters broadcast data simultaneously over both ANT+ and Bluetooth Smart protocols, ensuring universal compatibility with almost any modern cycling device.

Whether you are riding outdoors or training inside, your 4iiii power meter will seamlessly connect to a massive catalog of head units (like Garmin, Wahoo, and Hammerhead), GPS smartwatches (like Apple Watch and Garmin Forerunner), smartphones, and indoor cycling apps like Zwift and TrainerRoad.

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INSTALLATION

How Do I Install My Shimano Crank After Receiving a 4iiii Power Meter?

Installation steps vary between crank models. Always follow the manufacturer’s instructions, or consult your local bike mechanic for assistance. Shimano-specific installation instructions are available for all supported models - find the relevant document for your crank below:

Crankset Use	Crankset Model	Installation Instructions
Road	105 FC-5800 / Ultegra RC-6800 / Dura-Ace FC-9000	Shimano DM-FC0003
Road	105 FC-R7000 / Ultegra FC-R8000 / Dura-Ace FC-R9100	Shimano DM-RAFC001
Road	105 R7100/Ultegra FC-R8100 / Dura-Ace FC-R9200	Shimano DM-RAFC010
Gravel	GRX FC-RX600/810	Shimano DM-GAFC001
MTB	XT FC-M8000/M8020	Shimano DM-FC0002
MTB	XTR FC-M9000/M9020	Shimano DM-MAFC001
MTB	XT FC-M8100/8120/XTR FC-M9100/9120	Shimano DM-MAFC002
MTB	XTR FC-M9200/9220	Shimano DM-MAFC010

Important: After installing the crankset, spin it by hand and confirm there is clearance between your frame and the power meter pods on both the drive and non-drive side. If either pod contacts your frame, do not ride your bike - contact support@4iiii.com immediately.

Can I Install a 4iiii Power Meter Myself?

No, 4iiii power meters cannot be installed at home because the process requires specialized manufacturing tools, precise calibration, and trained technicians to ensure our rigorous ±1% accuracy standard.

The power meter pod must be permanently bonded to the crank arm in a highly controlled environment. Self-installation is not an option. To get a 4iiii power meter, you must either purchase a pre-installed Ride Ready crank or send your existing crank to our facility (or an authorized international partner) for a Factory Install.

Can 4iiii Factory Install on a Crank That Has Stickers, Crank Skins or Has Been Painted?

No, because the Factory Install process involves high heat and requires removing a small section of surface paint to permanently bond the pod to the metal or carbon, all protective skins or stickers must be removed before shipping.

Leaving stickers or crank boots on your crank arm can interfere with our manufacturing and calibration process, and they will likely be damaged by the heat treatments we use.

Can I Move My 4iiii Power Meter to a Different Crank?

No, the 4iiii power meter installation is a precise, permanent bonding process. Attempting to pry off or remove the power meter pod from the crank arm will destroy the internal electronics and instantly void your warranty.

If you are upgrading to a new bike with a different bottom bracket standard, you cannot transfer just the pod. You will either need to transfer your entire crankset (if it fits the new frame) or purchase a new Ride Ready or Factory Install power meter for your new setup.

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WARRANTY

What Is the Warranty on 4iiii Power Meters?

4iiii power meters are backed by an industry-leading 3-year warranty. 4iiii Innovations Inc. warrants all power meters to be free from defects in material and workmanship under normal use for three years from the original purchase date.

The warranty does not cover defects resulting from improper use, accidents, excess moisture, insects, improper packaging for shipment, lightning, power surges, or unauthorized modification. At their sole discretion, 4iiii will repair or replace the defective product at no charge for parts or labor. The customer is responsible for shipping costs to 4iiii, with return shipping covered by 4iiii after repair or replacement.

Warning: The warranty becomes null and void if the product is repaired by anyone other than an authorized 4iiii representative.

Full warranty details are available here.

*The three-year warranty applies to power meters purchased from January 1, 2018 onward.

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Ready to Ride with Power?

Investing in a power meter is one of the most exciting steps you can take to elevate your cycling performance, and navigating the options shouldn’t feel intimidating. Now that you understand the differences between Ride Ready and Factory Install, know how to find your crank length, and are ready to check your frame clearance, you have everything you need to order with absolute confidence.

If you ever get stuck or have a highly specific compatibility question, our 4iiii support team is always just a message away.

Have more questions? Visit the 4iiii Help Centre

Ready to ride? Shop 4iiii Power Meters