My Garmin 510 had an elevation error yesterday, here are two similar rider:



The normal elevation is the top right and yesterday is the bottom left. Also notice the difference in the over all elevation - yesterday's ride was tracking ~400 ft above the correct elevation. I will be out on a ride later today to see if this issue continues.

Anybody have a similar experience? And suggestions to fix it?

D'OH! Wrong place for this thread, not e-bike... this should be in Electronics. Can anybody tell me how to move this thread? I'm going for another cup of coffee...

there is apparently a way to force it to follow the map instead of the barometric pressure. Or combine the two, I'm not exactly sure. Barometric pressure varies with weather, I have a ride recorded where my house is 300 feet higher in elevation when I got back because a low pressure front moved through during the ride.

I was under the impression that Garmin used the barometer to augment the GPS elevation, or is it the other way round, I can't remember. Anyway, general guidance is to acclimate the Garmin for a few minutes before you actually start your ride. I have heard every number from 3 to 10 minutes. If you are leaving from home, put your bike on the porch before you put your helmet and shoes on, fill your water bottles and fill your pockets with whatever it is you carry in your jersey pockets. That should be enough time to acclimatize the Garmin.

They look pretty close. I wouldn't worry about it. You can get errors due to changes in weather or rain. The opening in the case can get plugged when it's wet out affecting the readings.

Interesting, I was not aware of the barometer pressure part of the altitude. Yesterday, I did turn on the Garmin just as I walked out to the bike.

(and thank you to admin for moving my thread)

The thing that I'm seeing is the flat elevation on yesterday's ride versus the top right ride

If it exists, the barometer is used instead of GPS for elevation. Not all of the Garmins have barometers.

Cyclists are typically interested only in elevation gain (not absolute elevation).

What's the difference in elevation gain?

Differences of +- 20% in gain values might be fairly normal.

That's my point, elevation gain from yesterday 568 ft versus 1,276 ft in the earlier ride. Both rides are 18 miles. They are different routes, I expected less elevation gain yesterday, however, as you see the flat line, the Garmin was not tracking the change in elevation through a hilly route.

Maybe, the barometer wasn't working?

Garmin Connect has an "elevation correction" feature for data collected on devices without barometers.

Garmin's and Suunto's watches do this, but the Edge units are kind of primitive. Some Edge models will calibrate the barometer from a saved location, so if you save "home" with the correct altitude it will set/correct the baro elevation when you start and end your ride. But it's only the watches that will continually adjust the baro elevation to bring it closer to GPS elevation. That feature, FusedAlti, is basically considered the gold standard.

Nicer Edge units use air pressure/density to measure altitude. But that changes with weather. In fact wind is made out of changes in air pressure. You calibrate a barometer by telling it the current altitude, then it assumes that any changes to the air come from you going up or down hill. If the weather changes while you ride or it's windy, your barometer drifts slightly out of calibration. Also barometers are less accurate when in the cold. And when they've been moved thousands of feet up or down. These are reasons to re-calibrate a barometer.

Maybe in Florida. But a lot of cyclists like climbs. Here's somebody's list of the 100 best climbs in America.

When you're doing Hurricane Ridge, you start at 0 feet and end at 5,240 feet above sea level. It's only 17 miles and parts are harder than others so you can't pace yourself by distance. Knowing your current elevation tells you how close you are, how much to go.

That's true of any climb.

That's why your Garmin has a climbing screen with a data field to show you your current elevation.

Here is an example. This was an out-and-back ride, with the turn around point at ~42 miles. A couple miles prior to that, I got caught in a downpour and took refuge in a campgrounds office building until the worst was over. Note how the descent is shallower than the climb...until it appears I rode over a cliff at ~66 miles, (when the opening must have cleared). That was around the time I finally reached dry roads.

Yep. Red "circle" below shows how to do it in Garmin Connect.

"Elevation corrections" means use elevation from a database for the lat/lon points in your file, ignore whatever elevation is in the file and look it up instead. Garmin and Strava have this turned off for tracks from devices that have a barometer and turned on for everything else.

Sometimes the elevation corrections make it worse! With just a barometer, the ride in the pic below was 13 feet off (based on USGS topo maps), but when I turn elevation corrections on the error becomes about 850 feet.

You still don't need absolute elevation for this. That's true of any climb. Obviously.

And the kind of scenarios you are talking about aren't typical. Pointing out odd/strained exceptions to what's typical is silly.

Using the barometer is probably not a very good way of doing what you are talking about anyway.

It would be sort of easy if your ride happened to have the fairly-odd property of starting at sea level. But it would be hard to do on more typical rides where you don't and where there might be multiple climbs you want to keep track of. Hard enough that it's likely that no one really ever does it!

It might be easier to use the elevation graph that some of the Garmins provide (which doesn't need any elevation measurement to work).

yesterday was cool and windy. ~40F with 15 to 25 mph winds and I was out right after it rained.

I have used this 510 at much colder temps (down to -20F) - typically it appears accurate. However, at these low temps the Garmin does like to read much colder temps than the weather reports.

No you don't need a bike computer for this at all. You can guess. Knowing your elevation relative to your starting and ending point is the most convenient way though.

You're confused about something really basic, so we'll use the example I posted earlier to see if you can understand. Riding over Washington Pass from the valley floor meant starting at approximately 2,100 feet and ending at approximately 5,500 feet. Again the climb has steep parts and not so steep parts so distance is less useful for pacing than just knowing your altitude. If you're at 2,800 feet you've just started and better not be burning matches.

The fact that the Hurricane Ridge climb starts at sea level is just a neat feature of the ride. Thanks to math, you can do this anywhere. Climbs in the Rockies that start a mile up, for example.

You obviously don't have personal experience with big climbs on a bike but the concept is easy to grasp. I've heard about a ride called the Six Gap Century in GA with lots of vert.

GPS values vary for military/security reasons. The military gets accurate data all the time.

It's only "convenient" in fairly unsual situations.

You are still not getting that this is not a typical case!

It is probably easier to use an elevation profile that it is to keep track of the elevation reading.

That you've just started is enough.

You obviously have no idea about my personal experiences.

Rides like the Six Gap Century are a good example of why your technique of trying to keep track of elevation readings isn't anything anybody really would do.

If you'd done any climbing rides I wouldn't have to explain the basics to you. But if you'd rather argue on the internet, have at those font buttons.

Again...

There are easier ways of keeping track of one's progress. And it doesn't really work if there are multple rises and falls in the climb.

Again...

Today's ride seemed back to normal:
20.9 miles with 820 ft elev gain
Last time I rode a similar route:
21.4 miles with 925 ft elev gain

The lower elev gain today makes sense because I avoided the busy road, using a rail-trail instead. That can easily account for 100 ft difference. Here's hoping yesterday was an anomaly.

When you do a loop, does the gain (more or less) equal the loss?

While it could be posted in the 'Advocacy' forum. What is wrong with posting it here?