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GPS Units = Show road steepness?



 
 
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  #1  
Old March 10th 19, 01:46 AM posted to rec.bicycles.tech
Sir Ridesalot
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Posts: 4,681
Default GPS Units = Show road steepness?

Talking about GPS units on another thread reminded me of something else I wondered if they do. Does a bicycle GPS unit show you the steepness of roads? There's an area that I frequently ride where on road has short but very steep hills, another road a mile or so east of it has much more gradual hills whilst a third road to the west of the first one is a major highway that can be ridden with a bicycle. What I'm wondering is this: if someone unfamiliar with the area got there and used a GPS unit to show those three roads, would the GPS unit show them the different gradients of the roads? Or is that another function that they'd need to download or otherwise install?

Cheers
  #2  
Old March 10th 19, 02:34 AM posted to rec.bicycles.tech
Ralph Barone[_4_]
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Posts: 402
Default GPS Units = Show road steepness?

Sir Ridesalot wrote:
Talking about GPS units on another thread reminded me of something else I
wondered if they do. Does a bicycle GPS unit show you the steepness of
roads? There's an area that I frequently ride where on road has short but
very steep hills, another road a mile or so east of it has much more
gradual hills whilst a third road to the west of the first one is a major
highway that can be ridden with a bicycle. What I'm wondering is this: if
someone unfamiliar with the area got there and used a GPS unit to show
those three roads, would the GPS unit show them the different gradients
of the roads? Or is that another function that they'd need to download or
otherwise install?

Cheers


My Garmin 705 shows the slope as I ride it, and historically, but not
preemptively. For that, I used Google Earth.

  #3  
Old March 10th 19, 02:48 AM posted to rec.bicycles.tech
Duane[_4_]
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Posts: 1,546
Default GPS Units = Show road steepness?

Ralph Barone wrote:
Sir Ridesalot wrote:
Talking about GPS units on another thread reminded me of something else I
wondered if they do. Does a bicycle GPS unit show you the steepness of
roads? There's an area that I frequently ride where on road has short but
very steep hills, another road a mile or so east of it has much more
gradual hills whilst a third road to the west of the first one is a major
highway that can be ridden with a bicycle. What I'm wondering is this: if
someone unfamiliar with the area got there and used a GPS unit to show
those three roads, would the GPS unit show them the different gradients
of the roads? Or is that another function that they'd need to download or
otherwise install?

Cheers


My Garmin 705 shows the slope as I ride it, and historically, but not
preemptively. For that, I used Google Earth.



The edge 800 has an elevation screen.

--
duane
  #4  
Old March 10th 19, 02:47 AM posted to rec.bicycles.tech
Duane[_4_]
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Posts: 1,546
Default GPS Units = Show road steepness?

Sir Ridesalot wrote:
Talking about GPS units on another thread reminded me of something else I
wondered if they do. Does a bicycle GPS unit show you the steepness of
roads? There's an area that I frequently ride where on road has short but
very steep hills, another road a mile or so east of it has much more
gradual hills whilst a third road to the west of the first one is a major
highway that can be ridden with a bicycle. What I'm wondering is this: if
someone unfamiliar with the area got there and used a GPS unit to show
those three roads, would the GPS unit show them the different gradients
of the roads? Or is that another function that they'd need to download or
otherwise install?

Cheers


My Garmin can display the current gradient and I have that in my main
screen. There is also a page to show the upcoming elevations.

Generally though I look at the route in RideWithGPS before hand to get a
decent idea of what to expect from the elevation profile.

--
duane
  #5  
Old March 10th 19, 03:56 PM posted to rec.bicycles.tech
Mark J.
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Posts: 575
Default GPS Units = Show road steepness?

On 3/9/2019 4:46 PM, Sir Ridesalot wrote:
Talking about GPS units on another thread reminded me of something else I wondered if they do. Does a bicycle GPS unit show you the steepness of roads? There's an area that I frequently ride where on road has short but very steep hills, another road a mile or so east of it has much more gradual hills whilst a third road to the west of the first one is a major highway that can be ridden with a bicycle. What I'm wondering is this: if someone unfamiliar with the area got there and used a GPS unit to show those three roads, would the GPS unit show them the different gradients of the roads? Or is that another function that they'd need to download or otherwise install?

Cheers

As others have noted, many (all?) Garmin units can display gradient (as
in "6% grade". As noted in another thread, GPS units are notoriously
not very accurate in their altitude calculation, so the more expensive
units have a barometric "backup". If you are using a pre-loaded course
(e.g. a .TCX file) on your GPS, (?some? ?all? my!) Garmins can display
the profile of the upcoming few miles.

My own experience over 7 years with Garmin units (that have barometric
"backup" to the altimeter calculation) is that the reported gradient is
/fairly/ consistently reported (on many rides over the same hills),
though the peak steepness will vary by a percent or so. Maybe that's
'cause I wasn't looking when the highest number was on the screen, or
because the unit updated at different points on the road on different
rides of the hill.

Finally, if you use ridewithgps.com, and I assume any similar
sites/software, note that gradient reporting there usually misses peak
values, as the software tends to average over larger segments of the
course. For example, on one local hill I ride a lot, the peak gradient
appears to be about 12% for maybe 50-100 feet, as measured with both GPS
and inclinometer. Ridewithgps.com reports a peak of 7.2%, which is
probably true if you average over longer segments.

Mark J.
  #6  
Old March 10th 19, 07:11 PM posted to rec.bicycles.tech
Bertrand[_3_]
external usenet poster
 
Posts: 9
Default GPS Units = Show road steepness?

On 3/10/2019 10:56 AM, Mark J. wrote:
On 3/9/2019 4:46 PM, Sir Ridesalot wrote:
Talking about GPS units on another thread reminded me of something else I
wondered if they do. Does a bicycle GPS unit show you the steepness of roads?
There's an area that I frequently ride where on road has short but very steep
hills, another road a mile or so east of it has much more gradual hills whilst
a third road to the west of the first one is a major highway that can be
ridden with a bicycle. What I'm wondering is this: if someone unfamiliar with
the area got there and used a GPS unit to show those three roads, would the
GPS unit show them the different gradients of the roads? Or is that another
function that they'd need to download or otherwise install?

Cheers

As others have noted, many (all?) Garmin units can display gradient (as in "6%
grade".* As noted in another thread, GPS units are notoriously not very accurate
in their altitude calculation, so the more expensive units have a barometric
"backup".* If you are using a pre-loaded course (e.g. a .TCX file) on your GPS,
(?some? ?all? my!) Garmins can display the profile of the upcoming few miles.

My own experience over 7 years with Garmin units (that have barometric "backup"
to the altimeter calculation) is that the reported gradient is /fairly/
consistently reported (on many rides over the same hills), though the peak
steepness will vary by a percent or so.* Maybe that's 'cause I wasn't looking
when the highest number was on the screen, or because the unit updated at
different points on the road on different rides of the hill.

Finally, if you use ridewithgps.com, and I assume any similar sites/software,
note that gradient reporting there usually misses peak values, as the software
tends to average over larger segments of the course.* For example, on one local
hill I ride a lot, the peak gradient appears to be about 12% for maybe 50-100
feet, as measured with both GPS and inclinometer.* Ridewithgps.com reports a
peak of 7.2%, which is probably true if you average over longer segments.

Mark J.


Here's an article on the trickiness of measuring steepness:

http://www.roberts-1.com/b/v/e/08a/i...ring_steepness
  #7  
Old March 10th 19, 09:38 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 1,260
Default GPS Units = Show road steepness?

On Sunday, March 10, 2019 at 11:11:41 AM UTC-7, Bertrand wrote:
On 3/10/2019 10:56 AM, Mark J. wrote:
On 3/9/2019 4:46 PM, Sir Ridesalot wrote:
Talking about GPS units on another thread reminded me of something else I
wondered if they do. Does a bicycle GPS unit show you the steepness of roads?
There's an area that I frequently ride where on road has short but very steep
hills, another road a mile or so east of it has much more gradual hills whilst
a third road to the west of the first one is a major highway that can be
ridden with a bicycle. What I'm wondering is this: if someone unfamiliar with
the area got there and used a GPS unit to show those three roads, would the
GPS unit show them the different gradients of the roads? Or is that another
function that they'd need to download or otherwise install?

Cheers

As others have noted, many (all?) Garmin units can display gradient (as in "6%
grade".* As noted in another thread, GPS units are notoriously not very accurate
in their altitude calculation, so the more expensive units have a barometric
"backup".* If you are using a pre-loaded course (e.g. a .TCX file) on your GPS,
(?some? ?all? my!) Garmins can display the profile of the upcoming few miles.

My own experience over 7 years with Garmin units (that have barometric "backup"
to the altimeter calculation) is that the reported gradient is /fairly/
consistently reported (on many rides over the same hills), though the peak
steepness will vary by a percent or so.* Maybe that's 'cause I wasn't looking
when the highest number was on the screen, or because the unit updated at
different points on the road on different rides of the hill.

Finally, if you use ridewithgps.com, and I assume any similar sites/software,
note that gradient reporting there usually misses peak values, as the software
tends to average over larger segments of the course.* For example, on one local
hill I ride a lot, the peak gradient appears to be about 12% for maybe 50-100
feet, as measured with both GPS and inclinometer.* Ridewithgps.com reports a
peak of 7.2%, which is probably true if you average over longer segments.

Mark J.


Here's an article on the trickiness of measuring steepness:

http://www.roberts-1.com/b/v/e/08a/i...ring_steepness


Since the usual GPS satellites are well over the horizon, using them to get an accurate altitude reading is difficult at the very least. Also the news ones are pretty low altitude and moving really fast. This compounds the problem.

So there has to be one hell of a lot of computation just to find your position let alone your altitude. Now let's make it more complicated - the MPU's use more energy the faster they operate so if you want your unit to last a long time and be reasonably compact AND do all of this computation you really have your hands full with just position let alone attempting to calculate altitude.

The way I would first look into it would be to use a satellite as close to zenith as possible and use signal transit time to calculate altitude.

  #8  
Old March 10th 19, 11:36 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 560
Default GPS Units = Show road steepness?

On Sunday, March 10, 2019 at 9:38:46 PM UTC+1, wrote:
On Sunday, March 10, 2019 at 11:11:41 AM UTC-7, Bertrand wrote:
On 3/10/2019 10:56 AM, Mark J. wrote:
On 3/9/2019 4:46 PM, Sir Ridesalot wrote:
Talking about GPS units on another thread reminded me of something else I
wondered if they do. Does a bicycle GPS unit show you the steepness of roads?
There's an area that I frequently ride where on road has short but very steep
hills, another road a mile or so east of it has much more gradual hills whilst
a third road to the west of the first one is a major highway that can be
ridden with a bicycle. What I'm wondering is this: if someone unfamiliar with
the area got there and used a GPS unit to show those three roads, would the
GPS unit show them the different gradients of the roads? Or is that another
function that they'd need to download or otherwise install?

Cheers

As others have noted, many (all?) Garmin units can display gradient (as in "6%
grade".* As noted in another thread, GPS units are notoriously not very accurate
in their altitude calculation, so the more expensive units have a barometric
"backup".* If you are using a pre-loaded course (e.g. a .TCX file) on your GPS,
(?some? ?all? my!) Garmins can display the profile of the upcoming few miles.

My own experience over 7 years with Garmin units (that have barometric "backup"
to the altimeter calculation) is that the reported gradient is /fairly/
consistently reported (on many rides over the same hills), though the peak
steepness will vary by a percent or so.* Maybe that's 'cause I wasn't looking
when the highest number was on the screen, or because the unit updated at
different points on the road on different rides of the hill.

Finally, if you use ridewithgps.com, and I assume any similar sites/software,
note that gradient reporting there usually misses peak values, as the software
tends to average over larger segments of the course.* For example, on one local
hill I ride a lot, the peak gradient appears to be about 12% for maybe 50-100
feet, as measured with both GPS and inclinometer.* Ridewithgps.com reports a
peak of 7.2%, which is probably true if you average over longer segments.

Mark J.


Here's an article on the trickiness of measuring steepness:

http://www.roberts-1.com/b/v/e/08a/i...ring_steepness


Since the usual GPS satellites are well over the horizon, using them to get an accurate altitude reading is difficult at the very least. Also the news ones are pretty low altitude and moving really fast. This compounds the problem.

So there has to be one hell of a lot of computation just to find your position let alone your altitude. Now let's make it more complicated - the MPU's use more energy the faster they operate so if you want your unit to last a long time and be reasonably compact AND do all of this computation you really have your hands full with just position let alone attempting to calculate altitude.

The way I would first look into it would be to use a satellite as close to zenith as possible and use signal transit time to calculate altitude.


For every position on earth the altitude is known (measured during a Space shuttle mission if I recall correctly). The information is available for free. I use it to correct the altitude measurements of my rides afterwards. It should be possible for a GPS unit to show the altitude based on the measured position instead of trying to calculate it or measuring it with a barometer.

Lou
  #9  
Old March 12th 19, 01:04 PM posted to rec.bicycles.tech
Rolf Mantel[_2_]
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Posts: 98
Default GPS Units = Show road steepness?

Am 10.03.2019 um 23:36 schrieb :

For every position on earth the altitude is known (measured during a
Space shuttle mission if I recall correctly). The information is
available for free.


The information is available but not in the necessary precision for road
gradients; uploading GPS tracks to Strava it is usually most meaningful
to replace the GPS altitude by 'true altitude' but look at the results:

https://www.strava.com/activities/1206896182

The first km, I am faster in the evening than in the morning so I assume
it's level or extremely slightly uphill, Strava thinks it's losing some
5m within 1 km.
Around km 1, there is a steep drop by 2m, followed by a climb of 2m
which is not visible at all in the track.

From km 6 to km 8 the track has a constant "climb" of 1m; Strava
interpolates a peak of 15m altitude into that which is not there in
reality.

Almost everything is correct to within a few m; the map-based
information produces a lot less spurious altitude gain and loss than the
GPS based information but this is not good enough for comparison of
gradients unless you're talking hills with 20m altitude gain or more.

I speculate my trip to work is 10m - 20m altitude gain in total on 11k
distance, the map brings it to 40m, GPS measurement typically around 60m.

Rolf
  #10  
Old March 10th 19, 11:29 PM posted to rec.bicycles.tech
[email protected]
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Posts: 560
Default GPS Units = Show road steepness?

On Sunday, March 10, 2019 at 1:46:44 AM UTC+1, Sir Ridesalot wrote:
Talking about GPS units on another thread reminded me of something else I wondered if they do. Does a bicycle GPS unit show you the steepness of roads? There's an area that I frequently ride where on road has short but very steep hills, another road a mile or so east of it has much more gradual hills whilst a third road to the west of the first one is a major highway that can be ridden with a bicycle. What I'm wondering is this: if someone unfamiliar with the area got there and used a GPS unit to show those three roads, would the GPS unit show them the different gradients of the roads? Or is that another function that they'd need to download or otherwise install?

Cheers


GPS can show the actual gradient but it uses some sort of averaging algorithm which means it has a delay. This makes it pretty useless IMO. Besides this what are you gonna do if you know the exact gradient at that moment? GPS can tell you exactly were you are. For navigation you need a routable map and navigation software. Often people have a too high expectations of a GPS based cycling computer and end up never using the navigation capability and just have an expensive cycling computer or head unit as they are called now because speed sensors, cadence sensors, power meters, radar, lights, action camera's, HRM and your phone all connect to the unit and show their information on the head unit or can be operated using the head unit.

Lou
 




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