I am having a problem with my Polar Power Sensor. I get different readings between the small and big chainring when I run a consitency test. I installed it according to the video, and the gap between the chain and the sensor is less that 10mm on the small cog/small blade combination - can't really make it any smaller.
Riding at 30km/h on the big ring (53) on my rollers, and then riding at 30km/h on the small ring (39) I get very different readings - 200W on the small ring, 110W on the big ring - heartrate is consistent, both at 65%.
The most important measure is the distance between chain and sensor when on largest cassette cog and big ring is less than 30mm. From my experience to get consistent readings across all the gears the chain should rub the sensor when on the smallest cassette cog and small ring.
With compact cranks I got the best results when it almost rubbed on the second smallest cassette cog/small ring combination too.
The most important measure is the distance between chain and sensor when on largest cassette cog and big ring is less than 30mm. From my experience to get consistent readings across all the gears the chain should rub the sensor when on the smallest cassette cog and small ring.
With compact cranks I got the best results when it almost rubbed on the second smallest cassette cog/small ring combination too.
Thanks mises, I will check this out. I'm a little bit puzzled how the sensor would give accurate readings if the chain is rubbing - surely this affects the vibration of the chain and hence the tension? Not that small ring/small cog is a combination that is used very often!
