Garmin question

[fossyant]

My Garmins do this if under trees - but it can be negated if you've got additional sensors. EG If not using the sensors with my Explore, you'll see the speed fluctuate slightly even with clear skys, but connect the sensors, speed stays rock solid.

 

[si_c]

My Garmins do this if under trees - but it can be negated if you've got additional sensors. EG If not using the sensors with my Explore, you'll see the speed fluctuate slightly even with clear skys, but connect the sensors, speed stays rock solid.

Also worth noting that speed sensors rely on consistent tyre pressure as they count wheel rotations and if your wheel size/tyre pressure changes this can have an impact on the reported speed.

Garmin units calculate the wheel diameter from distance travelled, but I don't actually know if this is an ongoing calibration of it's just done when you first pair the sensor. Probably worth checking at some point.

 

[fossyant]

Also worth noting that speed sensors rely on consistent tyre pressure as they count wheel rotations and if your wheel size/tyre pressure changes this can have an impact on the reported speed.

Garmin units calculate the wheel diameter from distance travelled, but I don't actually know if this is an ongoing calibration of it's just done when you first pair the sensor. Probably worth checking at some point.

Mine tends to do it every few rides, but it's used on 3 bikes, 2 of which have sensors (road bikes). The MTB doesn't have sensors (just another thing to fill with mud !)

 

[Dogtrousers]

To be honest, although I'm aware of this, it's not very important to me.

Most of the time I'm getting a good signal so it doesn't happen often
I don't very often actually look at my current speed anyway.
Over the length of an entire ride a bit of dithering in the path while I'm under trees isn't going to make any difference.

But that's just me.

But I bought a speed sensor anyway ...

 

[Supersuperleeds]

There is a stretch on the great central way in Leicester that does this to whatever device I use. I just presumed it is a dead spot for satellites.

 

[Aravis]

I have always imagined that the speed displayed on your screen when riding is the Garmin's best attempt to determine your current speed whilst in the process of gathering your ride data. I don't think this speed is captured anywhere, the speed displayed when you've uploaded your track being determined from the location and time data in the track. If so, it doesn't matter whether the speed you see when riding is accurate or not.

A more extreme form of signal loss occurred sometime last year when I passed through the Staple Hill Tunnel on the Bristol to Bath path while running 2 Garmins - a 200 and a 520. Both completely lost all signal in the tunnel of course. If I remember correctly, they "repaired" the loss differently. One replaced the missing section (a straight line would be a very good guess in the circumstances) but the other did not, slightly shortening the ride. At least I think that's what happened, and I can't remember which was which.

I will still have both .fit files squirrelled away...

 

[stephec]

If you use the desktop version of Strava you can correct the distance.

Under the list of boxes on the lefthand side, where you can look at HR data and so on, there's a box with three dots in it, click that and you have options to correct distance and elevation.