With more and more power monitors appearing on the market each year, the options for cyclists continue to expand. One of the newer players in the market is Power2Max from Germany. We test it and find a system that is superb in its accuracy coupled with ease of maintenance and use.
Back in the late 2000s, two German engineers working on wireless solutions for big car manufacturers such as Audi, BMW, and VW got into cycling, and found themselves unhappy with existing power meter quality and price points then available. Being engineers, they naturally decided that they could make a better system, and brought the first systems out in late 2010. This led to the Power2Max “Classic” system, which has now been largely supplanted by the “Type S” system that I was sent.
The Type S 5 bolt Power2Max mated to a FSA K-Force Light 172.5 mm crank, with choice of coloured decals to complement your bike. Wide variety of crank types and bottom bracket availability, or the unit can be purchased separately if you have compatible cranks.
Power2Max first hit the big times of the WorldTour with Team Movistar in 2014, coinciding with their move to Canyon bikes after 25+ years with Pinarello. I’m currently working with Dr. Mikel Zabala, Movistar’s Sport Performance Director, on a new book on cycling science. So with Mikel and I both being scientists and power junkies, I’ve been talking with him throughout 2014 on his experiences with Power2Max. As you’ll read, Mikel’s been extremely happy with the changes, and this is reflected in Power2Max now also sponsoring Etixx-Quick Step, Bardiani-CSF, and BORA-Argon 18.
Ordering and Installation
Ordering a system is simple. For North American customers, the power2max website has an online shop, and the main information needed is the crank type and length along with the bottom bracket standard. When I visited Michael Wegner at the North American distribution office and warehouse in Vancouver in early December, he had my request ready to roll, along with a massive pile of boxed units ready for shipment following Black Friday.
In my case, I asked for FSA K-Force Light cranks (172.5 mm) set up with BB86 bottom bracket for my Aquila cyclocross bike, as I had long wanted to get full-time power on the CX bike. Installation and setup really couldn’t be easier. Coming as a complete system built into the crank spider, there was no additional installation or setup beyond installing the cranks onto your bike. Tighten up the crank, bolt on my chainrings, hit “pair” on my computer, and that was all.
Each Power2Max unit is built with four strain gauges and an accelerometer built into the crank spider. One subtle marketing battle in the power meter industry is “strain gauge creep,” with the idea that more strain gauges equates to more accuracy and some systems touting up to 16 strain gauges. While sensible in one view, the alternate view is that more gauges are simply overkill and used to compensate for improper design. This is analogous to slapping on a lot of carbon fibre to achieve a set design, rather than achieving the same result with less material. More strain gauges also mean more potential points of failure mechanically and at the points of connection.
Being German and being engineers, the focus is on testing, testing, and some more testing. Besides feedback from pro teams like Movistar, production testing includes mechanical stress testing, functionality at different temperatures, waterproofness, and wireless testing.
Very clean system with no wires or any attachments dangling outside to get damaged. The two rubber caps on the bottom are removed to access screws for replacing the battery. With most bikes, this will require removing the cranks.
Data for scientists and engineers is the classic “garbage in, garbage out.” Power2Max has accurate measurements to ±2%, and this is tested across a very wide range of power outputs and environmental conditions during design and production. This includes testing to a custom rig certified by the German Institute for Calibration to be true to ±0.1% and with a resolution of 1° throughout the pedal stroke, such that testing at 90 rpm provides 540 data points each second. The Power2Max unit, set up to a chain and cassette, is then tested against the reference system throughout a wide range of power outputs, including at times up to 2,800 W. Such a dynamic testing rig seems to be unique to Power2Max in the power meter industry.
The black pod under the cranks house the transmitters and the batteries. Placing this under the cranks rather than on top also minimizes damage risk, as the cranks will likely turn if hit there rather than being jammed due to chain tension if placed atop the cranks.
One design characteristic of Power2Max is their reliability over time of the unit and its calibration. This involves designing the power meter so that its characteristics remain consistent over time. The “how” is at the heart of power meter design, which is why power2max doesn’t reveal exactly which design details make the difference. But the end result is that there is no need to send the system back to the manufacturer for re-calibration over time.
Depending on the computer head unit used, there is the ability to gain left/right power data. This is achieved by measuring the net force on each half of the pedal stroke, with the accelerometer in the unit providing markers to crank position. Note that this split power is a combined net power rather than true individual leg power. That is, right side power is the net result of both the right leg’s power from it going from 12 o’clock to the 6 o’clock position, minus any dead weight or negative power being provided by the left leg.
I do not have a head unit capable of this feature, but throughout 2014 I have extensively used another power meter featuring left/right pedaling power and force dynamics, and you can search our Pez archives for all the ways I have used this feature.
Forget It and Use It
Dr. Mikel Zabala, Sports Performance Director for Movistar, has been the one responsible for implementing Power2Max onto the team over their first season in partnership in 2014. Accuracy is obviously the primary parameters. Beyond that, some of the things that are absolutely critical to a professional team are ease of use and reliability. This is important to ensure both consistent data (having data from every training session and race) and of course trustworthy data.
On a simple practical level, imagine you’re Zabala and having to schedule phone calls with 27 athletes around the world to troubleshoot their power meter, all the while not being able to help monitor their training because of lost data. That would be enough to drive anyone to indulging in too much sangria.
From that perspective, Zabala has been thrilled with Power2Max. In 2014 he reported zero problems with the system with 27 riders and >100 units, both in racing and in training over 700,000 km. Remember that pro mechanics do non-recommended things like power-washing bikes daily, along with swapping cranks and chainrings regularly. Consider too the weather conditions that pros train and race in, not to mention the crash damage they sustain (remember Quintana’s collision with the guardrail in the 2014 Vuelta?), and that is pretty strong testimony.
The only maintenance that Zabala has reported has been replacing batteries, and that has occurred generally just on an annual basis for Movistar. When the time comes, the process can be quite easily done at home with removal of the crank, and requires a commonly available CR2450N battery available from most general stores.
If you are into tinkering with your equipment, then the Power2Max will not be much fun for you. That is because there is NOTHING to mess with when using Power2Max. Unlike other power monitors, there is nothing to attach to the frame that requires alignment or calibration with the monitor. This is because, rather than using a simple cadence sensor magnet, cadence is built into the Power2Max via an accelerometer. Zabala says that this is a small but important detail for the mechanics, as it means one less thing that they have to worry about when power-washing the bikes, or to check each day to get the bikes ready to roll.
Of course, ANT+ transmission means no wires anywhere with the system, transmitting directly to any other ANT+ head unit of your choice. Pairing with head units is as simple and reliable as we have grown to expect from this data transmission system. Currently mostly confined to riding indoors, the signal has been completely free from any interference from the various computers, projectors, fans and electronic trainers in my workout room, and the signal easily transmits more than a metre away to where the ANT+ stick is sitting with the computer.
Another feature that fitting with Power2Max’s “Simple2Use” philosophy, and what makes it annoying to tinkerers, is the automatic zero-offset. When active, every three seconds that you are not pedaling, the Power2Max automatically performs a zero-offset. This includes when you are still clipped into the pedals and coasting, not only when you are unclipped or have the crank in a particular position, and is an advantage of a crank spider-based power meter rather than ones at the crank arms or pedals.
One key variable affecting offset and accuracy is the temperature, as this will affect the strain gauges and the characteristics of the metal it is embedded within. Each Power2Max unit goes through a climate chamber for testing and calibration during production, and will compensate within the range of -20°C to +70°C. I’ve taken it riding outside in -6°C so far this winter, and have been known to brave it at times in -10 to -15°C, but their compensation range certainly includes any weather I feel like riding in.
Yet another simplicity feature of Power2Max is their compatibility across a wide range of chainrings. Power2Max can be compatible with any chainring that fits their 110- and 130-BCD bolt circle dimensions, along with specific ones for Campagnolo cranks. That includes both aerodynamic chainrings, the WickWerks 46/36 chainrings that I have on my cyclocross bike, and non-round chainrings from Rotor and O-symetric.
Swapping chainrings has no effect or need for full recalibration of the system, another huge benefit of the system. Indeed, Power2Max are OEM partners with Rotor, Praxis Works, and BOR, and can offer chainrings as an optional add-on with their systems. Overall, this cross-compatibility makes for ease of swapping across different chainring sizes or types.
Another nice benefit from Power2Max is the compatibility and choice between a wide variety of cranks. This includes both alloy and also carbon cranks due to measurement being at the crank spider rather than at the crankarms. Some of the crank manufacturers supported included FSA, Rotor, Campagnolo. Within these, you can choose from a wide range of bottom bracket standards and also crank lengths. With these choices, as was my case with my cyclocross bike, what you get is the crank built into Power2Max power meter crank spider. So all I needed was my existing bottom bracket and chainrings and I was set.
There is also the option, if you already have a compatible crank with a removable spider, to simply purchase the Power2Max crank spider. These options include Rotor, Specialized S-Works and FACT, Cannondale Hollowgram, and SRAM S900, Force22 and Rival22. Obviously, this offers an extra cost savings.
And to make power even more cross-compatible, Power2Max has systems available for track (both full crank/spider and spider-only) and MTB (full Rotor cranks). That makes for a very comprehensive range of products that can really advance the use of power in these disciplines.
What I really like is the true plug and play nature of the Power2Max. From design and construction, through to chainring compatibility and auto-zeroing, there really is nothing to worry about or do with the system once it’s on your bike.
I will have to hold off on durability and toughness evaluations for another few months until I get through some of the early season gravel races (aka mudbaths), but I don’t anticipate any problems with weathering whatever southern Ontario can throw at the Power2Max. That’s because there really is nothing exposed anywhere that can possibly get damaged, except for an extremely remote possibility for the transmitter part under the crank getting hit. Otherwise, the system appears extremely well-sealed to the elements, and my limited time outside to date has shown no signs of any data drops or spikes.
• Check out the Power2Max North American website.
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