Rotor Power cranks

This is a bit of a second coming for Rotor Power. After the initial launch in autumn 2012, it all went a bit quiet and sourcing a pair of the Power cranks proved to be a bit challenging. Production delays and a few technical glitches later, Rotor cranks have finally landed.

The recent influx of power meters has significantly increased customer choice both in terms of brands and the way power is measured, with each system having different merits. The reason why Rotor opted for crank arm measurement is obvious – it already had the vessel with which to do it.

Rotor’s existing 3D cranks are conveniently constructed with three hollow chambers in each crank arm and it’s these chambers that house four tiny strain gauges, eight in total. These strain gauges measure tiny deflections in the crank under the load, calculating the difference between pedalling and resting load. Of course, a huge benefit of using both cranks is the ability to gather right/left balance data.

While ultimately it’s the number of watts you’ll want to see, the Rotor system also measures and breaks data down to a more detailed level giving you torque efficiency and pedal smoothness outputs – effectively giving you the ability to name and shame one of your legs that may be shirking work at any point in a pedal revolution.

Aluminium alchemy: a bfore and after shot

A bit like other power measuring devices we’ve seen of late, exactly what you display your numbers on is down to you. It uses the industry standard ANT+ so there’s a vast selection to choose from, although it uses Garmin as a platform for software updates, hardly surprisingly as owner of the aforementioned ANT+ .

Rotor claims it’s 98 to 99 per cent accurate (of actual) and unlike some measuring devices, Rotor says, it’s unaffected by temperature change, in part due to the location of the strain gauges not suffering from as much expansion or contraction as other 
power measuring systems.

Each crank houses four strain gauges

The other upside of a crank power measurement is that it’s compatible not only with Rotor’s own ovalised chainrings, and the majority of other manufacturers’, but also with a significant amount of the myriad bottom bracket sizes out there.

At £1,450 it’s a considered purchase, and one only presently worth buying if you have a PC. Apple fans will have to wait a while until it becomes Mac-compatible.


Rotor cranks: team up with your choice of BB and chainrings

This article was first published in the October 3 issue of Cycling Weekly. Read Cycling Weekly magazine on the day of release where ever you are in the world International digital edition, UK digital edition. And if you like us, rate us!