Originally Posted by
curveship
It has two, one absolute (barometric) and one relative (stagnation pressure), but only the relative one is used in calculating power. The barometric sensor is used to record altitude just like a Polar or Ergomo. It *does* use the barometric data to calculate air density, which in turn is used to convert the stagnation pressure into a windspeed. But power calculations go straight from the stagnation pressure reading.
well either barametric pressure is a variable in it's calculation or it isn't. If it used barometric pressure to convert stagnation pressure to wind speed then it's just as important. I was more thinking about the ibikes need to use change in altitude as a variable and it using pressure for that anyway though.