Power measurement has for a long time been the preserve of professional cyclists. People watching the Grand Tours on TV will regularly see Chris Froome staring at his stem, and are reliably informed that he is paying close attention to his power output. Commentators talk regularly about the power that professional racers generate in the last few seconds of a race, and it’s clearly something that matters at the top end of the sport. However, power meters are now the talk of the town amongst recreational cyclists, and look set to become the “must-have” gadget. The single reason for this is price: power meters are actually becoming affordable.
For many years, power meters cost more than your typical road bike, so very few amateur cyclists could justify this expense of collecting power data. The LIMITS power meter is a new release for 2016 that effectively solves the price problem. Let’s see how it stacks up in terms of installation, build quality and accuracy.
Like all power meters, LIMITS power meter is a small device. Its unique feature is that it sits between the left pedal and crank arm, and comes with a few widgets to make installation possible. Once installed, this system pushes the pedals out by around 15mm each, which is potentially of concern to people who are sensitive to their pedalling geometry and style.
Despite the extra pedal spacing, the massive advantage is that you can easily swap this device between bikes (and bikes needing different types of pedal).
The installation instructions state repeatedly that you must not try to tighten the power meter onto the crank arm by turning the power meter itself, as it is only a lump of plastic that is attached to the tough metal spindle. This warning is fair enough, but I do wonder just how much abuse the power meter can take – from a clumsy foot clip-in, for example, or a knock against a kerb or tree root. Can it handle off-road and urban riding, or is it better suited to more genteel disciplines like time trialling?
An important part of the installation is calibration, and we achieve this through the ANT+ compatible bike computer (otherwise known as the head unit). The accuracy of this configuration is affected by the crank length, so it’s necessary to let the power meter know (via the head unit) what the crank length is. I had mixed results from different units, however: the Garmin Edge 500 detected the LIMITS meter but failed to calibrate it; the Garmin Forerunner 310XT calibrated it but had no ability to set the crank length; the Garmin Edge 1000 calibrated it and had the option of setting the crank length. The newer the bike computer, the better!@LIMITSCycling Power Meter are designed to be affordable, so all cyclists can power their performance… Click To Tweet
During early testing I found two issues:
The 3s average power reading jumped around considerably; the 10s avg reading was much smoother (ie, usable)
Readings were consistently more than with my Stages power meter – around 15 – 20% higher
The LIMITS company was quick to respond to negative feedback around short-term stability, and released a firmware update that (for me, at least) made the 3s average reading usable. The power levels also started to track much more accurately with my Stages meter. It is still early days in the analysis, and I won’t go into details here, but the LIMITS power meter is starting to deliver. The company is also being responsive to customer feedback, but it is a bit disappointing that they originally delivered a product with firmware that didn’t seem to handle the bumps and rumbles of real roads very well.
After only 13 hours or so of riding (over 9 days) my head unit indicated that the batteries were running low. This was quite disconcerting, and not remotely similar to LIMITS’ own assurance that “excellent battery life means you’ll need to replace your power meter batteries only once a year”.
Summary of Limits Power Meter
Since the company’s own firmware update, the most recent test rides have been promising in terms of live head unit readings and Stages meter comparison. On the face of it, this could be a decent way to cheaply measure power and switch it easily between bikes. However, these are very early days for the LIMITS power meter, and only time will tell how well this little plastic package lasts down at the end of the crank. If you are keen to get into monitoring your power output and are willing to accept the risks associated with running a “cutting edge” product, then the LIMITS meter is worth a go.