This Spanish product aims to reduce the time spent outside the rider's theoretical power zone and comprises of an eccentric hub connected to a pair of arms that move independently of one another.
This system effectively reduces the size of the gear when either left- or right-hand crank arm is at the top of the stroke and can be tuned to vary the point at which this happens. We found that the middle setting was the most effective and that it was easier to 'hold on' to a gear when climbing a steep gradient out of the saddle, delaying the onset of fatigue on long climbs. Further to our previous test of the system we feel that the weight it adds to your bike is justifiable if your cycling takes in lots of climbing and the engineering quality goes a long way to reconcile the cost.
In addition to the compact version tested here, Rotors are available in all double and triple chainring configurations including a single-speed version with a 34t chainring and a dummy inner chainring designed to protect the bearings.