Power meters are measuring devices that record the rider's performance on the bike. The pedalling power allows you to structure your training and set the right pace for your abilities on the road. Different measuring systems compete with each other. The most important question is: Is the data reliable?
Powermeter as a cycling training partner
Greg LeMond once called his power meter "my best training partner". The American was a true pioneer, one of the first professional cyclists to use the mobile power meters from Uli Schoberer (SRM) - that was in 1992. 32 years and three generations of professionals later, the best professional cyclist in the world today is much less euphoric about the topic of power measurement. Tadej Pogacar told the Youtuber Peter Attia in an interviewthat he didn't really trust the performance data and therefore also paid attention to heart rate measurement and climbing performance in metres per hour. At this point, a considerable number of the spectators must have frowned and wondered what Pogacar was trying to say. Because the actual experience is this: Over the years, power metres have become better and better and at the same time more affordable.
Powermeters become reliable
Over generations of devices, all the problems that initially made mobile power measurement so difficult have been worked on and solved - the influence of the ambient temperature has been eliminated, the effect of different chainrings on the calibration has been removed, the measurement of uneven pedalling has been made possible (oval chainrings), and the technology now works with astonishing precision even under off-road conditions. Even power measurement pedals now provide very reliable data, although the technology had to be extremely miniaturised. Does Tadej Pogacar really not trust his power meter? Or is he just expressing the fact that he has so much exuberant energy that he couldn't care less about the power data? We can only speculate, but many experts who heard this interview probably immediately guessed what it was about and why the interviewer refrained from probing further: so as not to force Pogacar to get his sponsor into trouble. Pogacar's team is sponsored by industry leader Shimano.
Not everyone trusts power meters
Shimano's power meters have a rather poor reputation, in contrast to the often very good mechanics of the Japanese company. This is partly due to the fact that several testers have publicised the problems of the Shimano power meter. Ray Maker aka DC Rainmaker and Shane Miller aka GP Lama have exposed the problems on their YouTube channels and included measurement data from their users in order to increase the database. Judging by the published data, Shimano has a design problem with its power meter, which often, but not always, displayed strange things in the tests. This erratic behaviour fuels the uncertainty that Pogacar addressed.
How exactly is exactly?
We were therefore very keen to investigate the Dura-Ace power meter and took a close look at a standard power meter fitted to a Canyon Aeroad after a test enquiry to Shimano went unanswered. Who knows, maybe Shimano has secretly made improvements? In contrast to mechanics, electronics offer the possibility of working on devices at any time, even retrospectively, via firmware updates. That's what Shimano has done. Have the Japanese been able to eliminate the weak points of their power meter?
According to our findings, not quite. The power display changes depending on whether the chain is being ridden on the small or large chainring. On the small chainring, the system clearly shows too much power. Shimano's solution: Tell the power meter where the chain currently is and correct the values accordingly. To do this, the power meter is connected to the drivetrain via an app. This is reminiscent of the cheating software used in the car industry. But on average, the displayed values are actually better after this correction, although this is at the expense of the correct left-right distribution, which is reversed by the manipulation. This procedure is therefore not really convincing.
Fluctuations and deviations
Another new power meter that disappoints with deviations that exceed the specified measurement accuracy is the SRAM Red AXS. In the past, SRAM Quarq power meters were always a safe bet. However, the SRAM Red in the test consistently shows too much power - regardless of the cassette used. A deviation of four to five per cent is uncharacteristically high: 315 watts instead of 300 watts is a substantial difference; the device is specified with +/- 1.5 per cent. All the Favero pedals, the SRM crankset and a Power2max crank run in perfect synchronisation. And the SRAM Rival cranks, which measure on one side, also display reasonable values, provided the legs actually perform the same, as the values on the left side are simply doubled, which is potentially prone to error. For whom which power meter is the best choice under which circumstances and what you can do with it if you can trust the data, are revealed in the following articles:
