Bizarre Garmin Elevation Foible

meanredspider

So when I commute home on my MTB the elevation gain on my Garmin 800 is recorded at a pretty consistent 340m

EXACTLY the same commute on my Volagi with EXACTLY the same Garmin 800 and the elevation gain is a pretty consistent at 305m (3 journeys)

What's going on? The only thing I can think is it has something to do with how they are mounted. On the MTB, it's on the handlebar to one side. On the Volagi it's mounted on the stem and sits just behind the AyUps lights (which I also use on the MTB). I wonder if the proximity of the Garmin to the AyUps is causing the difference despite the barometric correction?

itboffin

meanredspider wrote:

So when I commute home on my MTB the elevation gain on my Garmin 800 is recorded at a pretty consistent 340m

EXACTLY the same commute on my Volagi with EXACTLY the same Garmin 800 and the elevation gain is a pretty consistent at 305m (3 journeys)

What's going on? The only thing I can think is it has something to do with how they are mounted. On the MTB, it's on the handlebar to one side. On the Volagi it's mounted on the stem and sits just behind the AyUps lights (which I also use on the MTB). I wonder if the proximity of the Garmin to the AyUps is causing the difference despite the barometric correction?

Clearly there's something wrong with the Volagi, you should stick to riding the MTB, send me the Volagi and i'll have a look at it for you :roll:

All heart I am

pangolin

Probably it's mounted a bit higher on the MTB, and over the ride that all adds up.

PHYSICS.

rolf_f

Not enough data points yet. And you could do with recording atmospheric pressure too.

Ultimately, these things are noisy - taking a few trips home on the same route in the last week or two the recorded elevation total ranges from 500 to 750 odd feet. I think the higher figure is more accurate and more consistent but it does show how far out things can be. I've never taken the barometer seriously anyway!

arthur_scrimshaw

pangolin wrote:

Probably it's mounted a bit higher on the MTB, and over the ride that all adds up.

PHYSICS.

itboffin

Actually come to think of it my garmin must be playing up as well because it keeps saying 15mph when i'm going 25mph

and it adds time to the end of my rides, you know 1-2 extra hours - borked for sure

meanredspider

What's odd is just how consistent the difference is (rides from the last two weeks)

Volagi - 306, 299, 303

Cube - 356, 330, 340, 341, 335, 324

There's a small difference in the temperature the rides were at and, I suppose, the Cube rides were more likely to be under a steady "High" pressure system with the clear skies and cold mornings. There's also a difference in speed. I have to scrap my theory about the AyUps as the 299 ride was last Friday with no AyUps fitted.

In the end it doesn't really matter but I like to understand these things

arthur_scrimshaw

meanredspider wrote:

What's odd is just how consistent the difference is (rides from the last two weeks)

Volagi - 306, 299, 303

Cube - 356, 330, 340, 341, 335, 324

There's a small difference in the temperature the rides were at and, I suppose, the Cube rides were more likely to be under a steady "High" pressure system with the clear skies and cold mornings. There's also a difference in speed. I have to scrap my theory about the AyUps as the 299 ride was last Friday with no AyUps fitted.

In the end it doesn't really matter but I like to understand these things

The Volagi - that's a American bike? Could be a CIA tracking device causing interference, you doing stuff you shouldn't?

arthur_scrimshaw

On a more serious note, I thought the Garmin got it's elevation data from triangulation data from the satellites, I've sometimes lost gradient information displays when going through heavily wooded areas on the mtb, it returns when I emerge from the trees.
None of this would explain the phenomena you're describing though?

pangolin

I suppose it has to be the temp or the average pressure that is throwing it.

You could use the Cube on the next day when you would normally take the Volagi and see what you get?

It has a barometric sensor right? Maybe being shielded from the wind behind something on the Volagi affects that? I have no idea where on the unit this sensor is or how it works...

meanredspider

pangolin wrote:

I suppose it has to be the temp or the average pressure that is throwing it.

You could use the Cube on the next day when you would normally take the Volagi and see what you get?

It has a barometric sensor right? Maybe being shielded from the wind behind something on the Volagi affects that? I have no idea where on the unit this sensor is or how it works...

It could be. The barometric sensor I think is a small tapping in the base of the device. I'm not over-excited about taking the Cube just because it's hard work over 35 miles (800+ miles this year on knobblies and my thighs are like balloons! ;-) But I could.

Let's see what the ride home tonight gives.

meanredspider

Another 306m on the Volagi....

itboffin

meanredspider wrote:

Another 306m on the Volagi....

as i said send it to me and the bike just to be sure i'll test is all FOC and have them back to you, say ......2 perhaps 3 years at the most, perhaps.

rick_chasey

All that moving up and down on the suspension adds up ;-)

First.Aspect

Its the speed you are going.

If its an atmospheric barometer, it takes a few seconds to adjust. At a higher speed, there are probably a few dips and rises recorded on the other bike that aren't picked up.

Next question.

meanredspider

Rick Chasey wrote:

All that moving up and down on the suspension adds up ;-)

Looked out suspension

First Aspect wrote:

Its the speed you are going.

If its an atmospheric barometer, it takes a few seconds to adjust. At a higher speed, there are probably a few dips and rises recorded on the other bike that aren't picked up.

Next question.

Seriously? 2 mph difference at this time of year. By the time the summer comes, my ride will appear flat!

bompington

Just add 2,500 spacers and the discrepancy should be fixed.