To the Point: Power Meters
For many competitive road cyclists, power meters have become an integral part of their training program, allowing them to monitor their wattage output and alter their workouts accordingly. Until recently, the use of a power meter hadn't been as common with mountain bikers. The number of options approved for off-road usage was limited, and many were prohibitively priced, especially for the privateer racer. That's beginning to change, and with the growth of enduro racing, more and more racers are starting to look towards training with power as a viable option. We spoke with Matt Pacocha, Stages Cycling's marketing manager, to find out more about power meters and their usage as a training tool for mountain bike racing.
How does a power meter work?
What are the most common types of power meters available for mountain biking? Is one kind more accurate than another?
How does a power meter work?
We should talk briefly about power in the most basic sense, first. By definition ‘power’ is the rate at which work is done. When speaking about power in the context of riding a bike, power is the force that the rider puts into their pedals multiplied by the speed (or cadence) at which they apply said force. There are two ways for a rider to make more power on a bike: apply a higher force at a steady cadence, or pedal faster while applying a steady force. A true force-based power meter measures ‘power’ by measuring force through the deflection of a component—crank arm, spider, or torque-tube in a hub—multiplied by the RPM of the rider. This explanation is simplified, as there are unit conversions that need to happen, but this is a reasonable way to understand the basis of the feat.
Crank based meters like our Stages Power meter use strain gauges to measure the deflection of the left crank arm caused by a rider’s pedaling input. We measure a rider’s cadence using multiple
Crank based meters like our Stages Power meter use strain gauges to measure the deflection of the left crank arm caused by a rider’s pedaling input. We measure a rider’s cadence using multiple
sensors on our PCB (printed circuit board) including an accelerometer, which eliminates the need for an externally mounted magnet. Keeping a magnet aligned to measure cadence on a mountain bike is more of a challenge than one would believe.
Above all, it’s important for riders to understand that a power meter is merely a tool, and it’s up to riders to learn how to use the tool—or employ a coach—in order for it to better their performance with it.
Above all, it’s important for riders to understand that a power meter is merely a tool, and it’s up to riders to learn how to use the tool—or employ a coach—in order for it to better their performance with it.
What are the most common types of power meters available for mountain biking? Is one kind more accurate than another?Power meters come in the same forms for mountain riding as they do for road use. They can be spider, hub, or in the case of Stages Power, crank arm based. Each design has its own benefits and costs.
A hub increases unsprung weight and requires adjustments to damping settings and spring weights. It’s also a wear item. A spider-mounted meter must deal with a myriad of factors that can affect their deflection measurements, including chainline, chainring bolt torque, chainring size and the affect changes to all of these factors have on the meters ability to gather an accurate deflection measurement. While we are particularly proud of the job our design does in eliminating most of the above factors, we too deal with costs and benefits. You’ll note that though we take a very clean and accurate single sided measurement, we do assume symmetry on the rider’s part and double the value of their left leg.
All of these examples illustrate that each design has positives and negatives, and it really comes down to the design philosophy of the manufacturer and engineers. In the end, our internal testing, and the testing of countless third-party media outlets, basically support that all of these designs can do a decent job of measuring power when used to the manufacturers’ specifications.
A hub increases unsprung weight and requires adjustments to damping settings and spring weights. It’s also a wear item. A spider-mounted meter must deal with a myriad of factors that can affect their deflection measurements, including chainline, chainring bolt torque, chainring size and the affect changes to all of these factors have on the meters ability to gather an accurate deflection measurement. While we are particularly proud of the job our design does in eliminating most of the above factors, we too deal with costs and benefits. You’ll note that though we take a very clean and accurate single sided measurement, we do assume symmetry on the rider’s part and double the value of their left leg.
All of these examples illustrate that each design has positives and negatives, and it really comes down to the design philosophy of the manufacturer and engineers. In the end, our internal testing, and the testing of countless third-party media outlets, basically support that all of these designs can do a decent job of measuring power when used to the manufacturers’ specifications.
The Stages Power meter only adds 20 grams to the non-drive side crank arm, is unaffected by temperature changes, and can transmit data via both ANT+ and Bluetooth.
Are there advantages over using a power meter vs. a heart rate monitor for training?Absolutely. At present, power data is the most contemporary metric a rider, or their coach, can use to assess fitness and adaptation through training. Power offers more insight than any of the other metrics, because it exactly quantifies the amount of work the rider has done. It does this while being unaffected by wind, temperature or the condition of the rider. By integrating power data with other metrics like heart rate, speed, elevation gain and loss, a rider can clearly quantify gains and losses through training and racing. Furthermore, a power meter can be used as a pacing tool, so that a rider puts out the precise effort they need to get to a finish line as quickly as possible.
Why are power meters so expensive?Ha! Right, everything is expensive these days. I tell you, the left crank arms we buy from Cannondale, Shimano, SRAM, and FSA are surprisingly expensive. But when it comes down to it, our power meter is a complex electronic device that measures deflection, cadence, and temperature in a challenging area with amazing precision.
The Stages Power meter spent three years in development before it was ready to be sold, which required a team of engineers to dial in hardware and firmware, this all cost money, of course. We’re proud that we’ve been able to cram all we have into our meter—that being ANT+, Bluetooth, accelerometers, thermistor thermometers, and memory—not to mention that cut the point of entry to the category in half.
We’re also very proud to be making them in right here in Boulder, Colorado, with American workers. We make a majority of the components in the US as well. The strain gauges are made in the US. We shoot our ABS/PC housings with a vendor here on the Front Range. Yes, this stuff is a bit more expensive, but it’s something that we have great control over and we’re proud of. The more riders get to know our company the more they’ll realize that we have a real set of ideals and ethics at our core, it’s not just about beating the price down as low as it can possibly go, but making a good product that works extremely well, and selling it a fair price, and by fair we mean fair to our customer, our company and ultimately the workers making it.
The Stages Power meter spent three years in development before it was ready to be sold, which required a team of engineers to dial in hardware and firmware, this all cost money, of course. We’re proud that we’ve been able to cram all we have into our meter—that being ANT+, Bluetooth, accelerometers, thermistor thermometers, and memory—not to mention that cut the point of entry to the category in half.
We’re also very proud to be making them in right here in Boulder, Colorado, with American workers. We make a majority of the components in the US as well. The strain gauges are made in the US. We shoot our ABS/PC housings with a vendor here on the Front Range. Yes, this stuff is a bit more expensive, but it’s something that we have great control over and we’re proud of. The more riders get to know our company the more they’ll realize that we have a real set of ideals and ethics at our core, it’s not just about beating the price down as low as it can possibly go, but making a good product that works extremely well, and selling it a fair price, and by fair we mean fair to our customer, our company and ultimately the workers making it.
Yeti's Jared Graves uses a power meter extensively as part of his training regimen.
Power meters are used extensively by road cyclists, but what benefits would a power meter bring to a DH or enduro racer?Power meters can help mountain bike racers many of the same ways. Obviously, the usage and translation is near identical in the cross-country and marathon realm, with it being an extraordinary advantage in regards to pacing the latter event.
The perfect case study for power in enduro is Yeti’s Jared Graves. This man is an amazing athlete. Jared also follows one of the strictest training regimens we’ve ever seen a cyclist follow. He drove a lot of development for us over the last year in regards to mountain bike use, and at Interbike he sent more than a few of his professional peers into our booth looking to gain advantage from our product. We can’t imagine a greater ‘thank you’ or true opinion than recommending a product to peers you respect.
The first thing our Stages Power meter did for Jared was to give him a map of what an enduro race looked like in terms of wattage output data. This allowed him to best tailor his training to match his race efforts. When a rider is racing a series annually with the same events year after year, having a year of data at their fingertips is of massive benefit. Jared now can say, “ok, Enduro des Nations is three weeks away, I need to fine tune this particular effort.” You can imagine the confidence this gives a pro. He can show up knowing his body is dialed for that specific event… it must be awesome.
The other advantage Jared mentioned was using our meter to pace the transfer stages, so that he would arrive to the specials on time, but without expending any more energy than needed. Again, a huge help when dealing with an event like Punta Ala with no up lifts.
For the downhillers, like Yeti’s junior downhill world champion, Richie Rude, using a power meter in racing is mostly about better understanding the effort—and where they falter—then dialing in their intervals to better train. Obviously, no one is looking at their numbers during a downhill race, but that data is still super important to understand and analyze post event.
The perfect case study for power in enduro is Yeti’s Jared Graves. This man is an amazing athlete. Jared also follows one of the strictest training regimens we’ve ever seen a cyclist follow. He drove a lot of development for us over the last year in regards to mountain bike use, and at Interbike he sent more than a few of his professional peers into our booth looking to gain advantage from our product. We can’t imagine a greater ‘thank you’ or true opinion than recommending a product to peers you respect.
The first thing our Stages Power meter did for Jared was to give him a map of what an enduro race looked like in terms of wattage output data. This allowed him to best tailor his training to match his race efforts. When a rider is racing a series annually with the same events year after year, having a year of data at their fingertips is of massive benefit. Jared now can say, “ok, Enduro des Nations is three weeks away, I need to fine tune this particular effort.” You can imagine the confidence this gives a pro. He can show up knowing his body is dialed for that specific event… it must be awesome.
The other advantage Jared mentioned was using our meter to pace the transfer stages, so that he would arrive to the specials on time, but without expending any more energy than needed. Again, a huge help when dealing with an event like Punta Ala with no up lifts.
For the downhillers, like Yeti’s junior downhill world champion, Richie Rude, using a power meter in racing is mostly about better understanding the effort—and where they falter—then dialing in their intervals to better train. Obviously, no one is looking at their numbers during a downhill race, but that data is still super important to understand and analyze post event.
www.stagescycling.com
Photos: Wil Matthews Photography
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Its better to fit a FUN meter, it only adds 0.65g to your brain's capacity to have fun on a bike.
Borrowed a power-meter for my road bike and learned a lot about how to ride faster, but more importantly how to ride longer. Centuries became much easier, and more importantly, less painful, I could ride 100 miles Saturday, and go for an MTB ride Sunday, previously centuries put me off the bike for a few days recovering. Likewise, I understand how to preserve myself on a marathon MTB ride, and where most of my riding buddies can't ride 2 days in a row, I can, despite them being in better overall shape than I am and generally being better riders than me. Taking it seriously has allowed me to ride 6-7 days/week, pedal through trails I used to think were impossible, and see some really cool stuff while out on my bike.
More miles = more smiles.
I would think the most accurate would be through a hub where you have it straight laced drive side and crossed on nds (so you could measure the strain going through the body of the hub, which would act like thin walled cylinder strain). Though that method would be the most complex and add unsprung weight (as was noted in the article).
If you race, but train by just riding along "pinned" wait until you stop improving, then if you care, figure out how to train for real and get a power meter. You will be happy about it.
Training gives your engine more horsepower. It's hard to argue that more horsepower doesn't make you faster. Power Meters are the most effective training tool ever.
One can train strength and overall cardiovascular health fairly easily, but as stated in the article power integrates how fast work is done.
Thus, data from a power meter, is useful in putting yourself in a position to be heavily "prepared" if you will, for the physical demands of the application with a great level of detail., (road biking, XC, enduro, etc.); because now you can assess and train specifically, power distribution, overall strength, and cardio specific to the needs of the application.
With a power meter, you could look at what the maximum power output's you had during a given race were, how long they lasted, etc. Now comes training season. Try to develop a training regimen that mimics those same patterns, but you can now make measurable goals, such as wanting to increase your max power output by x amount of watts, as well as the duration that you are able to exert such a force, relative to the patterns and duration's of the data you collected real time on the track.
I wrote this rather quickly, but I think now you can start to see how it could be useful for professional athletes, and or those who have the cash, and want to evaluate their training very seriously and from as many angles as possible.
That aside, I know alot of riders, most of them xc who 'desperately' want a power meter, a very effective way of training/keeping track of your training (Joe Friel's Mountainbiker Training Bible , very good book if you want to read about the physical training side of mountainbiking, states power zones next to the heart rate zones for excercises, so thats a good start and takes a look at training with a power meter). But, indeed, the article is right on track there: expensive, not very suitable for a mountainbike, etc.
This looks promising so do the Garmin pedals( they're for a road bike, but you never know...) and read some rumors about a Japanse producer of consumer goods taking upon it, which could bring down the price significantly.
I for sure want one.
Is it like a normal ant, but way bigger, that carries all of the data to your computer?!?!
.
$899.99 for a simple device mounted to an XTR crank arm.... you having a giggle....
Probably $15 electronics at large enough volume, so you must be manually calibrating each one manually using David Beckham to do the work!
Then there is a crank arm.
Trust me, I know how much electronics cost to develop, patent, market, support etc. It is what I do and have done for over 15 years.
Mac -Aravan has the right idea.... it is about what they think the market will pay.
Look at the likes of freelap, a pole would cost around $1 to mass produce, yet they cost around 100 times that to buy.
Mobile mass market devices make minimal profit per item sold.