RideWithGPS

[Jeremy McCreary]

Surprisingly, no threads with RideWithGPS in the title, so I thought I'd start one with this question:

My recorded elevations are consistently 100-200 ft too low — which puts most of the Coast Highway between Oceanside and Del Mar, CA below sea level. As you might imagine, this is something CalTrans has gone to great lengths to avoid.

Any ideas? RideWithGPS tech support suggested an inaccurate barometer (their default source of elevation data) in my Android phone. But the barometric pressure reported by another app looking at the phone's barometer is nowhere near that far off.

BTW, anyone interested can find more useful info on RideWithGPS in this thread.

 

[dodgeman]

I stopped using it, it would no longer save my rides, I tried reloading it and it didn’t help. I’ve been using Strava instead.

I had to look up if phones have a barometer. They do. I’m a retired land surveyor and assumed they used gps for elevations. How much does a barometer change with a few feet of elevation change, not much. GPS can give good elevations but it takes big money, out last gps system was $60,000. It doesn’t matter, barometer or gps the elevation is the weak point where the distance will be in the ball park.

 

[Stefan Mikes]

Jeremy: There is a thread by the title of "Are We Condemned To Strava?"
I stopped using smartphone apps for my ride recording. I use a Wahoo ELEMNT Roam v2 fed by the routes from RideWithGPS. Even if I find the Wahoo altimeter pretty accurate, I often correct the elevation gain with the Strava tools. In my opinion, any barometric altimeter would fail if the atmospheric pressure has changed on your ride; correct me if I'm wrong.

I found the Wahoo elevation gain measurements on shorter rides very interesting. There are two overpasses in my area. One gives a 7 m elevation gain, and the other is 9.5 m high. Wahoo is very consistent on these values!

 

[Jeremy McCreary]

Jeremy: There is a thread by the title of "Are We Condemned To Strava?"
I stopped using smartphone apps for my ride recording. I use a Wahoo ELEMNT Roam v2 fed by the routes from RideWithGPS. Even if I find the Wahoo altimeter pretty accurate, I often correct the elevation gain with the Strava tools. In my opinion, any barometric altimeter would fail if the atmospheric pressure has changed on your ride; correct me if I'm wrong.

I found the Wahoo elevation gain measurements on shorter rides very interesting. There are two overpasses in my area. One gives a 7 m elevation gain, and the other is 9.5 m high. Wahoo is very consistent on these values!

I'm more interested in elevation along the ride than in final elevation gain figures. And for that, is above sea level too much to ask?

Barometric altimetry is apparently the norm for smartphones these days, and a sudden change in barometric pressure could potentially throw it off. But I'm talking about a chronic problem in generally stable weather.

My phone's had its share of falls onto hard surfaces. Luckily, no known consequences — unless the barometer's been damaged. Seems like a barometer would have to be at least partly mechanical, even in a phone.

 

[Stefan Mikes]

I'm more interested in elevation along the ride than in final elevation gain figures. And for that, is above sea level too much to ask?

Barometric altimetry is apparently the norm for smartphones these days, and a sudden change in barometric pressure could potentially throw it off. But I'm talking about a chronic problem in generally stable weather.

My phone's had its share of falls onto hard surfaces. Luckily, no known consequences — unless the barometer's been damaged. Seems like a barometer would have to be at least partly mechanical, even in a phone.

Jeremy: While you raised a very interesting question, the elevation on my rides has become one of the least important matters to me Unless I'm taking a mountain holidays of course! Still, I perceive the data such as elevation and incline highly inaccurate!

 

[MinnBobber]

Surprisingly, no threads with RideWithGPS in the title, so I thought I'd start one with this question:

My recorded elevations are consistently 100-200 ft too low — which puts most of the Coast Highway between Oceanside and Del Mar, CA below sea level. As you might imagine, this is something CalTrans has gone to great lengths to avoid.

View attachment 151112

Any ideas? RideWithGPS tech support suggested an inaccurate barometer (their default source of elevation data) in my Android phone. But the barometric pressure reported by another app looking at the phone's barometer is nowhere near that far off.

BTW, anyone interested can find more useful info on RideWithGPS in this thread.

How easy is it to use for tech-challenged folks?

I have the basic app loaded as a local club member, and will be upgraded to higher level RideWith for becoming a group ride leader.

Is it true that with this higher level, I can have verbal directions thru my Bluetooth hearing aids/ can then leave my phone in my backpack ?

I hope to become comfortable in using it.

 

[Jeremy McCreary]

How easy is it to use for tech-challenged folks?

I have the basic app loaded as a local club member, and will be upgraded to higher level RideWith for becoming a group ride leader.

Is it true that with this higher level, I can have verbal directions thru my Bluetooth hearing aids/ can then leave my phone in my backpack ?

I hope to become comfortable in using it.

I'm no expert, but I'd say fairly easy to use. The online documentation is pretty good, but I still misunderstood some of the "handlebar mode" settings, wherein you determine how much the screen is on and when — with significant implications for phone battery life.

I know you can set up aubible turn directions and would think you could hear them over any Bluetooth device connected for audio.

Good luck.

 

[mschwett]

Surprisingly, no threads with RideWithGPS in the title, so I thought I'd start one with this question:

My recorded elevations are consistently 100-200 ft too low — which puts most of the Coast Highway between Oceanside and Del Mar, CA below sea level. As you might imagine, this is something CalTrans has gone to great lengths to avoid.

View attachment 151112

Any ideas? RideWithGPS tech support suggested an inaccurate barometer (their default source of elevation data) in my Android phone. But the barometric pressure reported by another app looking at the phone's barometer is nowhere near that far off.

BTW, anyone interested can find more useful info on RideWithGPS in this thread.

hmmmm. pretty large discrepancy. I’d recommend trying another free app at the same time on the same phone, and see if it’s as bad. cyclemeter and cadence would be my two suggestions.

cadence actually has an option (on iOS) to enable and disable the barometric altimeter. I always have it enabled, and I definitely see a delta of around 30 feet, worst case, depending on weather. it’s still much better than consumer GPS Elevation. the current elevation is an invaluable piece of data when riding, especially when you know the elevations of the tops of various climbs. definitely amuses me when it’s off by Negative 30 and I’m riding on a path or road which is clearly a few feet above sea level, but it shows 25 below, lol.

 

[6zfshdb]

I'm not sure how the barometric pressure sensors work in smartphones. Is it possible for wind pressure at riding speed to affect the reading? Is there any difference in the results if you keep the phone in your pocket?

I've never had much luck with ride stat apps. Since I prefer to keep my phone in my pocket, I use a standalone GPS receiver to record my rides. I set it to use geotagged elevation data from USCGS topo mapping to avoid errors caused by barometric variables.

 

[mschwett]

I'm not sure how the barometric pressure sensors work in smartphones. Is it possible for wind pressure at riding speed to affect the reading? Is there any difference in the results if you keep the phone in your pocket?

I've never had much luck with ride stat apps. Since I prefer to keep my phone in my pocket, I use a standalone GPS receiver to record my rides. I set it to use geotagged elevation data from USCGS topo mapping to avoid errors caused by barometric variables.

i use mine on the handlebars, and it works very well. have used a couple different ones, not affected by speed or wind that i can tell. it’s usually within 10 or 20 feet of know or marked elevations, with a max variance of around 30 feet as noted above.

correction to USGS topo maps can be pretty inaccurate depending on the grading of the road relative to the underlying/prior contours, the accuracy and sampling rate of the GPS track, and the resolution of the DEM/other USGS data.

 

[pxpaulx]

I gave up using dedicated apps - for the last 2 years I've been using a Garmin Instinct watch. I've had a few different smart watches, but this one is sort of a hybrid. Basic LCD screen, but built in GPS means I just need to start my ride with the watch and it gets great tracking and info once done.

Here is a slickdeals link to the e-sports edition which is currently just $80 on buydig:

Slickdeals - Garmin Instinct

The watch looks good (I've passed this one on to my wife and now have a solar version of the Instinct). You can ignore the 'e-sports' function, that is just an add-on to what is otherwise exactly the same as any of the other Instinct watches out there.


With Garmin's app, you get a ton of details:

Distance, Time, Calories burned, speed details, heart rate and heart rate zone, ascent/descent, all available in data and chart formats.

 

[Mr. Coffee]

I've used ridewithgps for some years, though always in conjunction with an external GPS and only rarely through a phone. I've not noticed any such consistent elevation errors on rides used that way. Sometimes I have noticed that rides would overstate or understate total elevation gain of the trip, though.

Until this year I used a Garmin Edge, which was basically fine but had (what I thought) was a poor user interface and confusing (at times) usability. I replaced it this year with a Hammerhead Karoo 2, which in my opinion is a much superior solution.

I'd say the very best two features of ridewithgps are their route planning tools, and their turn-by-turn navigation, which is still better than any dedicated GPS unit out there. Though hammerhead has closed the gap and I usually use that for when I need turn-by-turn navigation.

 

[tomjasz]

would think you could hear them over any Bluetooth device connected for audio.

My Phonak PL90 BT rechargeable HAs don't link with all BT-capable devices.

 

[smorgasbord]

FWIW, I use RideWithGPS regularly and the altitudes are pretty damn good.
I actually have an old U.S. Coast & Geodetic Survey Base Marker on my property, so I know the altitude there and what I get is within 10ft of that. Maybe it depends on the phone? I'm using an iPhone 14 Pro Max.

 

[6zfshdb]

FWIW, I use RideWithGPS regularly and the altitudes are pretty damn good.
I actually have an old U.S. Coast & Geodetic Survey Base Marker on my property, so I know the altitude there and what I get is within 10ft of that. Maybe it depends on the phone? I'm using an iPhone 14 Pro Max.

I'm sure this is much more information than you want or need but "recovering" and reporting the condition of these USCGS benchmarks has been a hobby of mine for many years.

Great precision was used in determining elevation when these benchmark disks were installed. However, you need to know that the elevation stamped onto some can represent the height above the geoid (the theoretical or smoothed out shape of the earth) These usually don't match sea level or the elevations indicated on topo maps. The difference varies with topography and is more accurate near the coast rather than in mountainous regions.

On those not specifically marked "Elevation Above Sea Level", you need to know the offset which you can usually find by going here:

National Geodetic Survey - Survey Marks and Datasheets

geodesy.noaa.gov

Select "PIDs" in the search by list and enter the alpha numeric code stamped on the disk to see the data sheet.

You might also be interested in the history of the one on your property.

 

[dodgeman]

I’m a retired land surveyor and the elevation stamped in those discs is not related to the geoid. What has happened is they have done a couple of vertical adjustments over the years and improved the accuracy of the elevations. For instance when the elevations were first done, in the 1920’s, they started from tidal gauges and they assumed the Pacific Ocean and the Atlantic Ocean were the same elevation, they aren’t.

 

[6zfshdb]

I’m a retired land surveyor and the elevation stamped in those discs is not related to the geoid. What has happened is they have done a couple of vertical adjustments over the years and improved the accuracy of the elevations. For instance when the elevations were first done, in the 1920’s, they started from tidal gauges and they assumed the Pacific Ocean and the Atlantic Ocean were the same elevation, they aren’t.

You are absolutely correct. My statement was poorly worded.

What I was attempting to point out is, GPS elevations will not agree with those stamped on a benchmark disk since GPS uses ellipsoidal height or height above the geoid.

GPS On Benchmarks

geodesy.noaa.gov

Many GPS receivers and cell phones use barometric measurements to determine altitude but are subject to atmospheric variations.

Sorry for any confusion.

 

[smorgasbord]

I'll post a picture of my Base Marker in a few days. May have to obscure the last couple of digits to stop people from tracking me down, though, lol.

 

[jabberwocky]

I've used a plethora of ride tracking devices and have always found elevation data to have some variability. I'm pretty sure data out of the barometric altimeters are pretty noisy and devices try and correlate to GPS data when they can and then ride tracking software tries to make sense of it as well.

For your case, I'd guess that the barometric altimeter calibrated itself to GPS elevation and was a bit off. Barometric sensors are reasonably good at tracking changes in elevation but aren't great at getting an absolute elevation on their own, since they just track changes in air pressure and air pressure is not constant at a given elevation.

IME with my various Garmin devices, I see weird elevation calibrations most often when I start my device and take off without giving it time to get a good GPS lock. It seems like it figures out 2d position faster than elevation in relation to sea level. So the profile (height of hills and such) will be reasonably accurate, but the absolute elevation (above sea level) can be off.

 

[dodgeman]

Not to be contrary GPS does work on the ellipsoid but most systems including what most cell phones will display are going to show you the ground elevation you are at. How it does this on cell phones I’m a little sketchy on, is it GPS derived ground elevations or if it’s barometric derived elevations.