Problem with my new Rally 100. My average power output normally ranges between 200-250w (based on two bikes one of which previously had 'spider' based Power2Max power meter (and after changing group set i have now installed Rally 100) and also another Lab71 new bike which again came with builtin Power2Max crank based, suggesting the same power output. HOWEVER the Rally 100 installed recently consistently shows power output ranging between 110-160w for the same speed. Is it faulty?? I do calibrate it every time before a ride and the same crank lengths (172.5)! Please help