With the growth of the power meter market, it's pretty easy to add one to a road bike. There are lots of choices to suit your preferred make, model, style, and budget. But on a cyclocross or gravel bike, the choices are more limited, largely because some of the power meter options on the market don't accept the chainring(s) you might like to use for cyclocross or gravel.
Let's take a look at some of the options for adding power to a cyclocross or gravel bike, and why you might consider each type. I'll also share some of my favorite make/models of power meters for cyclocross and gravel bikes.
The 3 primary types of power meters for cyclocross and gravel bikes, plus 2 unusual types
Spider-based power meters
Spider power meters are sophisticated (used by most pros) tech known for accuracy and reliability. Popular brands of spider-based power meters include Quarq, SRM, and Power2Max. You can get different spiders based on your planned drivetrain: 1x, 2x, etc.
The downside of a spider-based power meter is that they can't be retrofitted to cranks that lack a spider in the first place - think Shimano Hollowtech II crankarms, like GRX, Dura-Ace, Ultegra, 105 and so on. Other crankarm brands like some SRAM models, Easton, Cane Creek, etc. DO use a spider design by default, which makes upgrading easy on those brands - remove the factory spider and install the power meter spider in it's place, then just move the chainrings over.
For this reason, if you're upgrading a Shimano equipped bike to a spider-based power meter, it's going to mean a new crankset as well. Rotor's ALDHU crankset and other similar models are a common platform to build on - you get a new crank, a new power meter spider, and then install your old chainrings. That can get expensive quickly, since you need the spider power meter as well as a new crank! Rotor now has "24" type cranksets - designed to be drop-in replacements for Shimano. Choosing one of those options at least saves you from having to buy a new bottom bracket as well.
Spider power meters tend to be more expensive, so they aren't the best choice if you're on a budget. Instead, check out crankarm-based power meters, next...
Crankarm-based power meters
If you can't install a spider-based power meter due to the design of your crankset, consider a crankarm-based power meter. Crankarm-based power meters add "pods" to familiar, existing makes/models - think Shimano GRX, Dura-Ace; SRAM GXP, or Campagnolo. Those pods can be on a single side, offering one-sided power measurement, or dual sided, giving you the ability to measure both legs independently.
The primary benefit of a power meter based on the crankarm is the ability to continue using your preferred chainrings. That means you retain compatibilty with your existing drivetrain. Popular brands of crankarm-based power meters in this style include Stages and 4iiii.
When shopping for a power meter system based on the crankarms, you generally have two choices. First, you can buy a complete crankset with the power meter already installed, and second, for some brands, you can send them your used crankarm(s) to have the power meter installed - they then return the arm to you, ready to ride. That can be a little more economical, although you will have some downtime while products are shipped back and forth.
Installing this type of power meter is pretty easy - especially the single-side type that measure power on your non-driveside crankarm. You don't even need to remove the drive-side crankarm or touch the bottom bracket - just remove the left side crankarm and install the new arm instead.
Be aware that unlike spider-based power, occasionally crankarm-based power meters can have clearance problems on some bikes, when a "pod" on the back of the crank interferes with the chainstay. Before buying a crankarm-based power meter, carefully review the manufacturer's guidance - they'll show you exactly what and where to measure to make sure your bike has enough clearance.
Power meter pedals
Power meters based in the pedal(s) have three important strengths - first, a very easy installation process, second, the ability to quickly swap them between bikes, and third, broad compatibility with almost any bicycle - no worries about chainline, chainring BCD, or other factors.
You don't need to mess with the bottom bracket on your bike, or remove the cranks or chainrings to install power meter pedals. In fact, you don't need to know anything at all about your drivetrain brand, number of speeds, chainline, or chainring BCD, because power meter pedals work with anything! That makes them ideal for riders who are less confident in their wrenching abilities.
What are the downsides of power meter pedals? There are some important factors to consider, and the availability of your preferred pedal and shoe platform is a major one. The two players in this space, Garmin and SRM, both offer Shimano SPD-style pedals and cleats that look very similar to a Shimano XTR or XT pedal. If you prefer to use Time ATAC or Crank Brothers Eggbeater pedals for cyclocross or gravel riding, there simply aren't any power meter pedals available for those platforms, so you'd need to switch to Shimano SPD (or consider a spider or crankarm solution.)
Like cranksets, meter pedals come in single sided and dual sided options. With a dual sided option, power is measured independently on both pedals. You will of course pay for this privilege.
I expect power meter pedals to become increasingly common and more widely adopted on cyclocross and gravel bikes as the technology improves and more economical options hit the market. In February, 2024, Favero Assioma released their Pro MX power pedals, based on the SPD design with single and dual side monitoring options priced at $450 and $759, respectively. That's right in line with what it would cost you to add a power meter crankset, and of course, pedals come with the key advantage of being easily moved from bike to bike.
Most importantly, the Favero Pro MX is less expensive than Garmin's Rally option, and significantly less so than the stratospheric cost of the SRM X-Power ($1,499, yikes) which should make them available to riders who have been priced out entirely of power meters in the past.
Rear hub power meters
Power meters inside the rear hub is a largely obsolete design. If you own one already that works, by all means continue using it, but don't buy a used one at this time.
Hub-based power meters do have a key benefit - if you have multiple compatible bikes that happen use the same rear wheel size and number of gears on the cassette, it's easy to move your power meter hub wheel from bike to bike - just like removing the wheel to change a flat tire.
"Air Resistance" power meters
There are a few power meters that don't attach to your drivetrain at all. Instead, they attach to the handlebar and try to compute your power based on air resistance, speed, and an elevation measurement.
While the idea of not needing to touch your drivetrain is appealing, I think this type of technology has limited value for cyclocross and gravel riding, where short, intense accelerations and many turns and direction changes per lap would make measuring power based on air resistance very challenging, if not impossible.
What if I...
Q: What I have a bike with Shimano GRX and want to keep my existing chainrings?
a: The easiest and most economical way to get a power meter on a bike equipped with Shimano GRX is to purchase a Stages or 4iiii left-side GRX crankarm and leave the drive-side crankarm, chainrings, and bottom bracket alone.
Q: What I have a bike with Shimano GRX and want a spider-based power meter?
A: If you're willing to get rid of your Shimano GRX crankset, check out the Power2Max gravel / Rotor ALDHU kit. They've got a special spider designed to accept the unusual chainring BCD used on Shimano GRX rings. It also duplicates the unique chainline found on GRX bikes, so your front derailleur, if you use one, will continue to work.
Q: I heard Quarq is the best value spider-based power meter, but SRAM owns Quarq and I ride a Shimano-equipped cyclocross or gravel bike. Can I use a Quarq spider-based power meter?
A: Maybe. It depends on your desired gear ratios, and whether you have a 11 speed or 12 speed drivetrain. If you are running GRX, you are out of luck, there is no Quarq product that will accept the GRX chainrings. If you're running Dura-Ace / Ultegra / 105 11 speed, check out the Quarq DFour DUB spider-based power meter, which mounts on a SRAM crankset, but is designed to accept Dura-Ace R9100 series chainrings. If you're running Dura-Ace / Ultegra / 105 12 speed, Quarq doesn't have a fit (yet.)
Q: I ride all sorts of bikes and can't afford to add power meters to all of them - what should I do?
A: I recommend a set of Garmin Rally XC pedals. They'll work on your cyclocross, gravel, mountain bike or even a road bike if desired. You can share a single pair of shoes across all disciplines and move the pedals from bike to bike on key event days where measuring power is critical. There is a dual option with independent power measurement from both pedals, and also a more economical single-side option.
Q: What if I have SRAM 12 speed AXS road/cross/gravel components on my bike?
A: You're in great shape! SRAM has multiple choices for you, including economical single-sided crank-based power meters, as well as more sophisticated spider options. A Rival left-side crank-based power meter crankarm, for example, carries a list price of just $263! That's a fraction of what you'd spend on competing products. SRAM has a nice "wizard" that will recommend the right power meter based on the components on your bike that's worth checking out.