false current speed calculation in the forest

[idk]

Hi,

I've been a Locus user since 2011, mainly to look on the offline maps in the middle of the forest and to occasionally track my ride.

Anyway, I just got a heart rate sensor and a proper bike mount to keep my cellphone on and in sight during the whole ride.

I noticed, that the current speed reading while riding in the forest, with a lot of trees is up to 50% off from the actual speed (measured with my bike odometer). When I ride on an open area, the speed calculated by Locus is by a margin of 0.5 km/h the same as my bike odometer reads.

So it kind of makes, I guess the GPS signal in the forest is not too good, but the tracking itself (= the waypoints) are good and fairly accurate, the total distance of the trip matched by a deviation of about 200 meters on a 30km trip with the bike odometer. I also don't have the false speed problem with another app called "Sportactive" or runtastic.


How can it be, that Locus records the track/waypoints fairly correctly, but the speed calculation has a error of about 50%?