Fitbit Sense Heart Rate failing for short intense cycling - appears to be 'correcting' itself to 50%

[Filosophical]

When I start a run, the Sense picks up my heart rate quickly.(eg. to 165 bpm)

But when I cycle, the watch appears to self adjust - correcting itself to around half the actual heart rate. I can measure it around 160 to 180bpm and the watch shows 89. Why is the watch doing this and how can I get whatever 'correcting' algorithm it is running to switch off? It makes the watch useless for short intense cycle rides, as it takes 20 to 30 min to adjust to the correct heart rate.

Typically I have to slow down for the watch to catch up. If I cycle straight into an intense hill climb at maximum intensity, maximum heart rate, the watch shows barely above resting rate. Ironically when I get to the top, and relax to recover, then the hear rate goes up to 140 or so.

Does anyone else have this problem and can Fitbit do anything about it? Is it 'intelligently' adjusting the results because there's no running movement? It makes the watch pointless for recording short intense exercise. 

[Guy_]

Hi @Filosophical - the issue with the Sense erratic heart rate is well documented in the forums. Sometimes it vastly over reads and others it under reads, depending on the person and the exercise.

The good news is it is more accurate when not moving, so reports sleep [if not too restless] and resting heart rate reasonably accurately.

[t.parker]

Sense is very inaccurate during cycling. There is nothing you can do about it.