Forum home Commuter cycling forum Commuting chat

Garmin Stats

j_mcdj_mcd Posts: 470
edited September 2018 in Commuting chat
Does anyone know how Garmin calculates 'stuff'?

Just looking at my Strava details for the Ride100 and it seems that this years ride was only 2352 foot of elevation as compared to 4700ish for the last three years.

Does it do it from map altitudes or GPS and if it's the latter, can heavy cloud and heavy rain throw it out by that kind of magnitude.

Or is my 810 screwed and it's time to buy new tech?
Giant Defy Advanced 0 - Best
Planet X London Road - Wet
Montague Fit - Foldy thing that rarely gets used these days

Posts

  • smokey_baconsmokey_bacon Posts: 1,637
    Potentially Strava not the Garmin. Ive had a few commutes recently where minutes have appeared on the strava file that are not on the gps head unit or app. I would be surprised if the same applied to elevation.
  • dinyulldinyull Posts: 2,962
    j_mcd wrote:
    Does anyone know how Garmin calculates 'stuff'?

    Just looking at my Strava details for the Ride100 and it seems that this years ride was only 2352 foot of elevation as compared to 4700ish for the last three years.

    Does it do it from map altitudes or GPS and if it's the latter, can heavy cloud and heavy rain throw it out by that kind of magnitude.

    Or is my 810 screwed and it's time to buy new tech?

    Is it not the rain messing with your Garmin?

    Whenever it rains, heavily, my elevation info goes haywire - always under-reading.
  • elbowlohelbowloh Posts: 2,118
    Really don't know.

    My most recent group ride, i seemed to have ridden at 4 km/h slower than everyone else in the group even though we left and got back together (auto-pause was on). elevations are also wildly different (400m+).
    Felt F1 2014
    Felt Z6 2012
    Red Arthur Caygill steel frame ??
    Tall....
  • wongataawongataa Posts: 861
    j_mcd wrote:
    Does anyone know how Garmin calculates 'stuff'?

    Just looking at my Strava details for the Ride100 and it seems that this years ride was only 2352 foot of elevation as compared to 4700ish for the last three years.

    Does it do it from map altitudes or GPS and if it's the latter, can heavy cloud and heavy rain throw it out by that kind of magnitude.

    Or is my 810 screwed and it's time to buy new tech?
    Your 810 uses an altimeter for the altitude, just like every other similar device out there. If it is rainy it will under report altitude as the hole in the casing that leads to the sensor tends to get blocked with water. If you look at elevation profiles from my 800 you can see if when started raining as the graph becomes pretty flat at that point.
  • Ricky hRicky h Posts: 119
    If you click on your ride in strava (via web browser) and look at the elevation, underneath it is a blue line saying "correct elevation". Click on that and strava will recalculate your elevation using regular maps.
  • Ricky h wrote:
    If you click on your ride in strava (via web browser) and look at the elevation, underneath it is a blue line saying "correct elevation". Click on that and strava will recalculate your elevation using regular maps.

    As above, I do that with every ride recorded on my Lezyne Super GPS, although recent firmware updates have vastly improved the discrepancy between them.

    It seems to affect many GPS units that have barometers, regardless of brand, including Garmins.
    ================
    2020 Voodoo Marasa
    2017 Cube Attain GTC Pro Disc 2016
    2016 Voodoo Wazoo
  • vpnikolovvpnikolov Posts: 568
    wongataa wrote:
    Your 810 uses an altimeter for the altitude, just like every other similar device out there. If it is rainy it will under report altitude as the hole in the casing that leads to the sensor tends to get blocked with water. If you look at elevation profiles from my 800 you can see if when started raining as the graph becomes pretty flat at that point.

    And then there is Wahoo:

    https://support.wahoofitness.com/hc/en- ... Ride-Data-

    Superior to any other method out there! My Ride100 elevation was spot on without correcting it on Strava.
  • wolfsbane2kwolfsbane2k Posts: 2,957
    Ricky h wrote:
    If you click on your ride in strava (via web browser) and look at the elevation, underneath it is a blue line saying "correct elevation". Click on that and strava will recalculate your elevation using regular maps.

    There is a similar button on the garmin site - "Elevation Correction; Disabled) on the right hand side of an activity.
    Intent on Cycling Commuting on a budget, but keep on breaking/crashing/finding nice stuff to buy.
    Bike 1 (Broken) - Bike 2(Borked) - Bike 3(broken spokes) - Bike 4( Needs Work) - Bike 5 (in bits) - Bike 6* ...
  • If you divert away from the climbs, or the Garmin has a hissy fit and crashes before the hills, the elevation will be lessened.
  • j_mcdj_mcd Posts: 470
    Ricky h wrote:
    If you click on your ride in strava (via web browser) and look at the elevation, underneath it is a blue line saying "correct elevation". Click on that and strava will recalculate your elevation using regular maps.

    I didn't know about that at all, thanks! There's another one as well for distance which might be handy in some cases.
    Giant Defy Advanced 0 - Best
    Planet X London Road - Wet
    Montague Fit - Foldy thing that rarely gets used these days
  • mudcoveredmudcovered Posts: 725
    j_mcd wrote:
    I didn't know about that at all, thanks! There's another one as well for distance which might be handy in some cases.

    Edge810 uses barometric pressure for altitude gain/loss. Normally its more accurate than GPS derived data but it does tend to get seriously messed up by heavy rain as others have said.

    Mike
  • prawnyprawny Posts: 5,402
    Third (4th?) The rain comments I think the water gets in the sensor hole for the barometer and it just blocks any changes. Was it wet though this year? Seems unlikely?
    Saracen Tenet 3 - 2015 - Dead - Replaced with a Hack Frame
    Voodoo Bizango - 2014 - Dead - Hit by a car
    Vitus Sentier VRS - 2017
  • cougiecougie Posts: 22,512
    prawny wrote:
    Third (4th?) The rain comments I think the water gets in the sensor hole for the barometer and it just blocks any changes. Was it wet though this year? Seems unlikely?

    It was nasty nasty weather. Wet and windy. One of the few bad days of the summer.
  • prawnyprawny Posts: 5,402
    Wounder, I hate paying to ride my bike at the best of times, they could have at least arranged some decent weather ;-)
    Saracen Tenet 3 - 2015 - Dead - Replaced with a Hack Frame
    Voodoo Bizango - 2014 - Dead - Hit by a car
    Vitus Sentier VRS - 2017
Sign In or Register to comment.