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bicycle power meter

How to Buy a Bicycle Power Meter

Power meters have been around for nearly 30 years since SRM developed the first system in the late 80’s, however recently they have seen a dramatic increase in popularity. While the benefits of training and racing with a bicycle power meter have long been known, due to the increase in social media, books on power meter training, and growth in cycling in general – there’s more demand for power meters now than ever. As power meters have increased in popularity, more and more manufacturers are entering the power meter market, which means more power meters to choose from. More choice is always a good thing! But it also leads to the obvious question: “What’s the best way to buy a bicycle power meter?”

But with all the power meters available today, how do you determine which one is right for you? After all, there is no ‘one best’ bicycle power meter. The right power meter for you might not be good for the next person. Selecting a power meter depends on a number of personal factors such as bike type, budget and what features you are interested in. This is why we advise our customers to use a straightforward, systematic approach regarding how to buy a bicycle power meter. Let’s dive in.

Buy a Bicycle Power Meter

 

How to Buy a Bicycle Power Meter

Steps

While the following steps are logical enough, the order is important. For example, all too often someone gets set on a power meter only to find it’s not compatible with their bike. Or maybe the power meter doesn’t have a feature they want. Here are steps we recommend following when it’s time to buy a bicycle power meter:

  1. Determine bike type (road, MTB, track, etc.)
  2. Decide on the power meter type
  3. Determine compatibility
  4. Select a power meter based on features and budget

Below, we will walk through these steps one at a time.

 

1. Determine the Bike Type

This is by far the easiest step to buy a bicycle power meter. Hopefully you know what type of bike you ride! But it’s listed because it’s important. You see, certain power meters are only compatible with certain bike types. Take a pedal-based power meter for example. Garmin, PowerTap and bePRO all make them. However at the moment, they are only suited for road bikes. No pedal-based MTB power meter option currently exists. In general, there are more options for the road then there are for the mountain. Power meters started on the road so the market there is just bigger. However to be true, there are some great options for MTB riders and the market is continuing to grow. We think it could soon catch up with the road market.

 

2. Decide on the Power Meter Type

Power meters are typically classified by type – meaning where on the bike they are located. There are essentially seven areas on the bike to measure power.

  1. Crank (spider)
  2. Pedal
  3. Crank arm
  4. OPFM (Handlebars)
  5. Bottom bracket
  6. Hub
  7. Chainring

Every power meter type has its advantages and disadvantages. Some are compatible with only certain bike types, some are more expensive than others, some are easier to install and move from bike to bike than others, some offer features that others don’t, etc. We suggest you take some time to really understand the differences and nuances here. Or of course, give us a call and we would be happy to help.

 

3. Determine Compatibility

Compatibility refers to whether the power meter will fit with your current frame or components. For example, if you’re looking at a crank-based power meter, is it compatible with your bottom bracket? What about your chainrings? Maybe you’re looking at a hub-based power meter. Is it compatible with your current wheelset, or will you need to get a new one? Or maybe you’re looking at a pedal-based power meter? Is it compatible with your crank arms? What about your current cleats?

If the power meter you are dreaming about isn’t compatible with your bike or components, it’s time to look at another power meter. The last thing you want to do is buy a bicycle power meter only to later find out it’s not compatible with your current bike. And yes…this happens. Unfortunately, with hundreds and hundreds of bikes and set-ups, we can’t give you a cheat-sheet to use on this step. However, our product listings do contain a Compatibility section – so we suggest you look there.

 

4. Features and Budget

There are several features you will want to take into account when it’s time to buy a bicycle power meter. You’ll see that we have grouped them by tier. Tier 1 being the most important, followed by Tier 2 and Tier 3. Note that we feel strongly about the items in Tier 1. However the order of Tier 2 and 3 items are our opinion and it’s how we look at power meters. You might feel one of our Tier 3 items should be a Tier 2 for example, and that’s fine. There is definitely some room to move things around a bit to suit your liking. Alright, let’s check them out.

Tier 1

1. Accuracy

Obviously a tier 1 item, accuracy refers to whether the power meter is indeed measuring what it claims to be measuring. For example, if it’s transmitting 225 watts to your head unit, are you actually producing 225 watts, or are you producing 215 watts instead? While accuracy is a big concern, most power meters claim an accuracy of within +/- 2%. This, of course, is well within the needs of almost any athlete.

 

2. Consistency

Consistency in this context refers to the repeatability of measurement. Will your power meter transmit the same power reading for a given effort from one day to the next? When it comes to power measurement, it’s critical that your power meter be consistent on a day-in, day-out basis. Consistency is just as important as accuracy when it comes to using your power meter as a training tool. We address power meter accuracy and consistency in this article.

 

3. Reliability

Nothing is more frustrating than a piece of faulty equipment. You want your cycling power meter to work and be reliable, every day. Reliability is key when looking at power meters so be sure to do some research in this regard. Fortunately, most of today’s units rank high in terms of reliability so if you stick with a name brand, you should be fine.

 

4. Cost/Budget

Another tier 1 item, a power meter can cost as little as $299 PowerPod power meter, and go all the way up to the mid-$2,000s (SRM). Some of the more expensive power meters often come with features like independent left/right power measurement or Bluetooth SMART capability, as well as high levels of accuracy and consistency. However, this isn’t to say that a lower priced power meter can’t do the job. In fact, nothing could be further from the truth. The vast majority of power meters are very capable so don’t assume that more expensive is necessarily better. If you find a power meter that meets your criteria and is in your price range – than that’s likely a winner for you.

 

Tier 2

1. Transferability

Transferability refers to how easy the cycling power meter is to transfer from one bike to the next. If you have multiple bikes but only one power meter, it’s nice to be able to move the power meter from bike to bike. Some power meters are easy to transfer; others not so much.

In general, the easiest power meters to transfer are pedal-based power meters and OFPMs, such as the PowerPod. Hub-based power meters, assuming the hub is already built into a wheelset, are also easy to transfer because all you have to do is move the wheel from bike to bike. Next easiest are usually crank arm-based power meters. Then there are crank (chainring or spider) and bottom bracket-based power meters – which can be moved among bikes – but typically aren’t due to the time it would take to do so, as well as potential frame compatibility issues between your bikes.

Lastly, we note that where ‘Transferability’ ranks on your list will vary based on your needs. If you don’t move power meters very much, it will be low on your list. Vice versa if you transfer power meters frequently.

 

2. Installation

Installation usually goes hand-in-hand with transferability. Power meters that are easy to transfer are usually easy to install. Pedal- or crank arm-based power meters for example are usually the easiest power meters to install. Crank-based power meters on the other hand require more work. However, assuming you’ve purchased a bicycle power meter that is compatible with your bike and bottom bracket, even these are relatively straightforward to install, come with detailed instructions and mostly require common tools. In addition, assuming you’re not moving the bicycle power meter from bike to bike frequently, keep in mind that installation is a one-time thing. So even if the installation process is a bit more involved, we still view installation as a tier 2 item.

 

Tier 3

1. Left/Right Power Measurement

Some power meters offer independent left/right power measurement. With this feature, you can measure how much power each leg is generating independently. Admittedly, this was a tough one to rank and we could also see it as a tier 2 item. Left/right power measurement is a very cool feature, no doubt. However, there is some debate as to whether you can, or should, try to even out any imbalances you might find. There are two types of left/right power – actual and estimated.

Actual L/R

Power meters such as Verve Cycling’s InfoCrank or PowerTap’s P1 Pedals, measure both legs independently. They combine the data to give you total power. Verve does this by locating a power sensor on both crank arms. Whereas PowerTap does this by housing a power sensor in both pedals. With a power sensor on both the left and right side of the drivetrain, you can get true left/right power.

Estimated L/R

On the other hand, power meters such as PowerTap’s C1 Chainring only estimate how much of your total power is coming from each leg. This is because there is only one power meter on the bike (in this case on the chainring), so the power meter needs to make some assumptions. The C1 Chainring takes power from your left and right down strokes only and ignores the upstroke. Since the majority of your power comes from the down stroke, it can estimate the power distribution fairly closely, just not exactly. Let me be clear – many power meters don’t offer actual or estimated left/right power. So don’t view estimated L/R power as a drawback. Any type of L/R analysis is a positive.

 

2. Cadence Detection

Magnets

With this option, a magnet is attached to the bike frame and cadence is detected using a reed switch. For example, on a crank-based power meter, the reed switch will be located in the bicycle power meter itself. As the crank turns, the reed switch will pass by the magnet and the magnetic field generated by the magnet will set-off the reed switch. This is considered the most accurate way to measure cadence. However, a magnet has to be attached to your bike frame. It’s usually attached using adhesive tape or glue, and some prefer not to have to bother with this application.

Accelerometer

The majority of power meters use an accelerometer to measure cadence. An accelerometer is a device housed inside the bicycle power meter and measures proper acceleration. With an accelerometer, everything is internal to the power meter and there is no magnet to mount. However, some argue that a tiny bit of precision is sacrificed with the use of an accelerometer.

Crank Position System (CPS) Technology

Verve Cycling has figured out a way to measure cadence internal to the cranks, using the strain gauges to read the tangential load. Their algorithm uses Crank Position System (CPS) technology, which is able to accurately detect cadence pulses regardless of power or pedaling style. With CPS, you have the accuracy of a magnet without having to have one mounted to your bike.

 

3. Transmission Protocols

Your bicycle power meter will communicate with your bike computer or smartphone through one of two wireless protocols – ANT+ or Bluetooth SMART. Note that some power meters are compatible with both.

ANT+

ANT+ Logo

ANT+ is a 2.4 GHz wireless network which is used to send standard information wirelessly from one device to another. ANT+ allows your bicycle power meter to communicate with your head unit. Almost all power meters and head units are compatible with this technology.

Bluetooth SMART

Bluetooth SMART Logo

Bluetooth SMART technology is also a wireless protocol, however it allows you to connect your bicycle power meter with smart phones and tablets. There are currently only a few manufacturers using Bluetooth SMART. If you are set on using your smartphone as your cycling computer, you will want to find a power meter that has Bluetooth SMART functionality. Otherwise, the transmission protocol isn’t a big factor as all head units can interface with an ANT+ bicycle power meter. We also note that you should expect to see more and more power meters add Bluetooth SMART in the future.

 

4. Batteries

There are three aspects you need to factor in when looking at the battery for your bicycle power meter: battery type, battery life and the ease of which it can be changed.

Battery Type

The majority of power meters use easy to find batteries such as the CR2032 coin-cell battery, AA or AAA batteries. Just make a note of the battery type and make sure it’s one you can find in your area. If it’s not, it just means you should probably keep a stock on hand as to eliminate the risk of being without a battery when you need one. Note that some power meters, such as the PowerPod or bePRO, run on rechargeable batteries. In this case, you don’t have anything to worry about.

CR2032 Batteries

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Battery Life

Battery life is one of the most common complaints with many power meters. The last time we did the analysis, the average run time for all power meters on the market was right around 330 hours, but the range is wide. Some power meters will only go for 20-30 hours (however these are often rechargeable batteries). Others will last for several hundred or in the case of SRM, up to 3,000 hours.

Difficulty to Change

The act of changing batteries on the majority of power meters is pretty straightforward, so there is not much to discuss here. Note however that some power meters do make the process a bit easier than others. It’s also worth noting that in case of SRM, the power meter must be sent back to the factory for a new battery. (SRM uses propriety batteries in its power meters.)

 

5. Weight

All power meters add weight, some more than others. Power meters such as a left-side only crank arm-based power meter might only add 20 grams to your bike, while others might add closer to 300 grams or more. When factoring in the weight, remember to focus on added weight by taking into account the component you’re replacing. For example, if the crank-based power meter you’re considering weighs 700 grams, and your current crank weighs 500 grams, the net addition is 200 grams. While it’s important to pay attention to how much weight is added and where, it’s not worth fussing over. The benefits of training with power will more than offset any weight gain. If you’re a weight weenie (and we don’t say this is a bad way), weight might move up on your list, otherwise we think it’s safe to keep it here.

Summary – How to Buy a Bicycle Power Meter

So there you have it, our framework for how to buy a bicycle power meter. It might sound like a lot, but if you work through each step, one at a time, I think you’ll find it’s actually pretty simple. Not to mention you’re sure to learn a lot in the process. As always, were here to help so if you have any questions send us an email or give us a call.

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