Deep Dive: Contender’s Guide to All Things Power Meters

Picture this: you’re shopping for a new bike. You’ve visited a few shops, narrowed it down to two sleek-looking machines, and now you're standing there, trying to spot the difference. They look nearly identical, but one is hundreds more. So you ask, “Why the price jump?” The shop employee points and says, “That one comes with a power meter.”

You nod, but in your head, you're wondering: what is a power meter? Maybe you've heard the term before, or maybe it’s brand new to you, but either way, you’re not sure what it does–or why it would matter to your riding.

If this scenario is you, partially or in full, you’re in luck, as we’ve got answers. To help you make sense of the wide world of power meters, including what they are, how they can take your training to the next level (smarter, not just harder), and which one might be right for you…Contender presents our deep dive on all things power meters. To get there, we’ll crack this nut via the three parts below. 

Already have a good handle on power meters, or why they’re useful? Gold star! Feel free to jump to part 2 or 3. 

• Part 1: What is a Power Meter & How Do They Work 

• Part 2: Why Use a Power Meter

• Part 3: Buyer’s Guide: Qualities To Look For, How to Pick the Right Power Meter 

Part 1: What is a Power Meter & How Do They Work 

Okay, you’ve got my attention; what is a power meter?

To put it simply, a power meter is a way to measure effort, made possible by a small, bike-mounted device (we’ll get into the specifics shortly, hang tight). Cycling is a data-heavy sport, and power–measured in watts, or the amount of effort or energy one is putting into the pedals–is another piece of the puzzle, though arguably the most potent data point of all. Think of power as a truth of serum of sorts, laying bare what one is really producing on the bike. 

Got it. But how does a power meter actually work?

At the core of every power meter is a strain gauge, a tiny sensor that measures the force applied to the bike’s drivetrain. A thin strip of material is attached to the crank, spider, or pedal. When force is applied, the material deforms, changing its electrical resistance. 

The power meter reads these small changes in resistance and converts them into torque values. Since power is a function of force over distance, power meters also include a cadence sensor. Cadence, which is the rotational count of your cranks, is used as the distance traveled. Power (in watts) is calculated using some variation of this basic formula: Power = Force × Cadence. This setup ensures that power meters provide a consistent and reliable measure of energy output.

Are there different types of power meters? 

Yes. There are five broad types of power meters, including: 

• Spindle-Based Power Meters: Measures force through the crank's spindle, via left arm engagement, and is found on SRAM and CINCH cranks. The pros are a more discrete, clean placement on the bike, along with more modest cost; cons are limited compatibility (must match crank), and no dual-sided power reading. 

• Left Arm-Based Power Meters: Measures power from the left crank arm only, most common on Shimano aftermarket cranks. The pro is typically a lower price point and lighter weight; the con is a lack of data on both legs, including whether one leg is over- or under-estimating power output, which a dual-sided power meter can help to correct. 

• Spider-Based, Direct Mount Power Meters: Measures power at the chainring interface, commonly used in SRAM meters, or SRM. The pros are a clean aesthetic, more modest price point, protection from impact, and left/right measurement; the cons are crankset-specific requirements and an inability to transfer across bikes, as is the case with pedals. 

• Dual-Sided Power Meters: Provides independent left/right leg data, a nicer version of the solo left arm, also common on Shimano. The pro is more robust and accurate data, enabling a cyclist to correct left/right imbalance in power output; the con is a higher price point. 

• Pedal-Based (Single or Double-Sided): Power sensors built into the pedals, with single-sided or dual-sided options, most notably on Garmin power meters. The pros are easier installation, left/right leg measurement, and compatibility with most bikes; the cons are greater vulnerability to pedal strikes, and higher costs–especially to achieve left/right measurement. 

Part 2: Why Use a Power Meter

Why should I use a power meter? As Eddy Merckx famously said, why not just…ride? 

If you’re serious about improving your cycling performance, a power meter is arguably the single best tool you can invest in. Unlike heart rate (HR), which can be influenced by sleep, caffeine, stress, and fatigue, power meters provide a direct measurement of effort in watts. Going a click deeper, here’s why they are so valuable to one’s cycling performance and progression: 

• Accurate and Immediate Effort Measurement: in comparison to heart rate, which has a natural delay, power meters provide instant feedback on your effort. This is especially important during short, high-intensity intervals, such as 30/30s or sprints, where heart rate simply can’t keep up with the rapid changes in exertion. In workouts like these, your heart rate will eventually rise and stay elevated (commonly known as cardiac drift), but it won’t reflect the true effort of each interval, making a power meter the only reliable way to track and measure performance accurately.

• Better Analysis of Fitness vs. Fatigue: when combined with heart rate data, power can help assess overall fitness trends and how fatigue affects your performance.

• More Reliable Training and Racing Tool: power meters allow you to measure and track effort consistently over time. Going back to the fitness vs. fatigue equation, you can also use this during or after races to better learn your body, how it reacts, and to better time attacks. 

• Not Influenced by External Factors: heart rate can fluctuate based on sleep, hydration, stress, and caffeine intake, along with other factors, but power remains a stable measure of effort.

• Greater Visibility Into Overall Training Load: power meters also help determine overall training load more accurately than heart rate alone, by highlighting your Training Stress Score (TSS). Simplified, your TSS looks at how much power you’re producing on the bike and for how long, relative to one’s Functional Threshold Power (FTP). Developed by Training Peaks (full explanation here), it is broadly considered one of the most powerful performance metrics, and a key guidepost to avoiding overtraining. From a tech perspective, most cycling computers and watches are able to display one’s TSS, but it requires that the device be paired with a power meter. 

Part 3: Buyer’s Guide: Qualities To Look For, How to Pick the Right Power Meter 

I’m intrigued. Let’s say I want to get a power meter; what qualities should I look for? 

Great question. Big picture, the key considerations are pretty straightforward:

• Compatibility: will a given power meter work with your bike? If not, it’s a hard pass. To help you answer this question, be sure to check out our decision tree below. 

• Price: how much do you want to spend? Generally speaking, lower price to middle of the road power meters go for $300-$500, and tend to be spindle- or spider-based, or single-sided. Higher end power meters, which tend to be crank or pedal based, tend to range from $500-$1,400. 

• Data Rigor: do you require left/right power measurement? If yes, you’ll want to focus on dual-sided, pedal-based, or spider-based power meters. If not, a single-sided power meter will do just fine, along with being lower on price. 

• Transferability: do you require a power meter that can transfer from bike to bike? If so, you’ll want to stick with a pedal-based option, such as Garmin. If not, you’ll have a lot more options–and price points–at your disposal. 

Alright, let’s do this. How do I determine power meter compatibility for my bike? What brands does Contender carry? What are my options? 

Great questions. And since they’re all related, we’ll tackle them together, via the decision tree framework below. 

• If you have a road or gravel bike…the first step is to identify whether your cranks are SRAM or Shimano. 

  • If your road or gravel cranks are SRAM 8-Bolt…

    • You have two main options: the more affordable one-sided option, which involves replacing only the left arm, which is also your only option if running the Apex Force groupset. For a higher end, dual-sided option, SRAM makes spider-mounted meters on its Force and RED cranks, either as a 107 BCD Quarq spider with the rings of your choice, or a one-piece ring and meter combined, which reduces the weight. 

• • If your road or gravel cranks are Shimano…

    • You have two options, both fantastic, both made by 4iiii, including their left-arm cranks (more affordable), and dual-sided cranks, which offer more data, and enhanced accuracy. 

• If you have a mountain bike…same as above, you’ll want to start with the cranks, which again, are typically going to be SRAM or Shimano. 

  • If your mountain bike cranks are SRAM 8-bolt…

    • Your two options are just like the road: either a left-arm replacement, available for X0 and XX cranks; or a spider replacement, with several options, all offering dual-sided data. 

• • If your mountain bike cranks are the slightly older SRAM 3-bolt…

    • The only real option is a Power2Max spider-based meter, with a 104 BCD ring. 

• • If your mountain bike cranks are Shimano…

    • There are two main options. Most people will end up with a left-side 3rd-party crank from 4iiii, which is by far the easiest, most affordable way to go on a mountain bike. For a higher-end, dual-sided option, SRM makes a spider that fits directly onto XTR or XT cranks. 

• If you have an edge case or outlier type scenario…such as wanting to run a Quark power meter on Shimano cranks, or a SRM power meter on Shimano mountain bike cranks, it gets complicated, but rest assured, there is a path forward, and we have answers. The best route is to give us a call or come into the shop, and we can guide you to the right solution. 

Conclusion

Power meters are one of the most effective tools for improving cycling performance. By providing precise, immediate feedback on effort, they help cyclists train smarter, race harder, and monitor fatigue more effectively than other standalone metrics, such as heart rate, mileage, or elevation gain. Whether you're a beginner or a seasoned racer, investing in the right power meter–and pairing those watts with other performance metrics–can truly take your riding to the next level.  

Learn More

Whether you’re just power meter curious or ready to take the plunge, finding out what works with your bike, we’re here to help. Feel free to drop by the shop, send us a message, or give us a call at (801) 364-0344.