[Raymo853]

@Rod Smith 132033 wrote:

Anyone for mountain biking? Sixteener Ray is leading a ride in Fort Dupont Saturday at 10. http://bikearlingtonforum.com/showthread.php?9639-Sat-Dec-19th-Group-MTB-CX-Ride-in-Fort-Dupont Terrain difficulty is intermediate, casual to moderate pace. I’m planning on that for Saturday. How about an easy team ride Sunday possibly with beerneuring?

Oh man I am not running it this week, I am headed to Pittsburgh. Let me check this and that, but I will commit to the 23rd and/or 30th.

[Raymo853]

I did it a few years ago, maybe 2007? It rained and rained and rained. And was cold. I loved it. Getting to see so much of NYC from a bike at bike speeds was great. However, I do not have plans to do it again. I think it is need to do once event.

I agree do not find a hotel in Staten Island for this event. Manhattan is the place to stay to speed getting to the start and benefit from the free Staten Island Ferry ride back to Manhattan.

[Raymo853]

@Tim Kelley 131891 wrote:

You’ve used the word “assume” three times in your past two posts. Do you actually know or are you just guessing?

It is hard to be sure since Apple, Samsung, Motorola, Verizon, AT&T , …… do not release this information. They actually go out of their way to hide it.

My attempted message? Smart phones are great for what most of us use them for, finding stuff in the developed World and tracking ourselves. But people need to understand they do not offer the greatest accuracy or precision in location, that is why short segments on Strava are such a joke.

Regardless of this tangent subject, I still would like Strava to address the differences in map tiles used to build their heatmaps.

[Raymo853]

I too assume Strava uses the GPS capabilities of phones, but I also assume it also uses the other location methods when they are available. Yes most phones allow you to have the GPS antenna on while on airplane mode suppressing any cell or WiFi type location stuff.

[Raymo853]

I like the sweet sixteen lines of names.

Sorry but I am not going to be the most productive member this Jan and Feb. I am moving soon and getting ready for that is cutting into my riding time.

[Raymo853]

I did post that, however, things have changed. I had one on the 2nd, but skipped the 9th and have to skip this week, the 16th. And since I am soon to move away from DC, there are too many things to do to run a ride every week.

I was about to contact MORE and set the schedule for the first Saturday every month.

[Raymo853]

@Tim Kelley 131823 wrote:

Yes. And can you confirm that Strava uses wifi maps, triangulation from cell towers, and their own user location heatmaps to record tracks?

I assume Strava just uses the location as calculated by Android or IOS and does not directly access the GPS receiver and calculation algorithms. I actually wonder if Apple or Google would approve “normal consumer” apps that do unless the apps are very focused. Allowing apps to ignore your heavily researched and invested in datasets would defeat the purpose of having a smart phone OS.

Such an app is being marketed currently by Trimble Navigation. I am not sure if it is for sale yet, but it is for Android and IOS and directly accesses the GPS receiver and ignores the other location sources.

[Raymo853]

@Tim Kelley 131814 wrote:

Here’s another one: http://labs.strava.com/heatmap/#12/-76.09955/37.01174/gray/bike

And how do you get GPS signal in a tunnel?

Smart phones use more than GPS to locate and track you. Cell phone makers, service providers and consumer mapping products (Google Maps, IMap, Waze) actually prefer to use the other sources of your location (WiFi maps, triangulation from cell towers, their own user location heatmaps,…) as it is quicker, less math intensive, and uses less energy while hopefully offering them an edge on knowing where you are over other companies.

[Raymo853]

Another, and possibly understandable in light of National Security demands, are the roads on Andrews Airforce Base. There is a big drop off in the northern sections, and there are no gates at the locations of the changes.
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http://labs.strava.com/heatmap/#15/-76.87726/38.82246/gray/bike

[Raymo853]

I have also noticed some very odd mistakes in the heatmap. The heatmap is generated in a series of tiles then stitched together to produce a continuous image. Sometimes something odd happens with a single tile, and the there are very distinct changes along the edge of the tile. A close by example is Cedarville State forest. http://labs.strava.com/heatmap/#15/-76.83160/38.64195/gray/bike

The “heat” on the most popular trail out there just ends for no reason. There is nothing there at all to cause this, no place to turn, or even a good place to turn around. Plus the primary parking area is within the area shown with little riding heat.
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[Raymo853]

@hozn 131785 wrote:

The data should automatically refresh (every night?). How long ago was this corrected? It may be that our “is-it-different?” algorithm is not accounting for changes in elevation data only.

He has been an outlier on the graph for many days. At least since last week.

[Raymo853]

I am feeling guilty for not pointing out this risk in the original thread. I once somehow got a Schwable Racing Ralph tire on a Bontrager Rhythm rim. I do not know how. It never flatted which I should be very thankful for. The only way to get it off finally was to cut through the Kevlar bead of the tire. I was so mad, I may have suppressed the memory. But it ended my purchasing of Schwable MTB tires. I am sticking to Bonti AW3, Conti X-Kings and Maxxis Ardents henceforth.

[Raymo853]

Got a tech question. Is there a way to force a refresh of the data? There is a weird and incorrect outlier in the elevation data. Mark P had a ride that showed a very high and false elevation gain that was corrected later. (How was it corrected? Stava runs such elevation profile fixing algorithms in the background. Using digital elevation models in place of GPS or smart phone collection data.)

He is shown in the BAFS2016 records as having 123,889 feet of gain over just 152 miles. Or an average of about 15% grade the whole time. His own Strava profile does not show that, but only a gain of 4,524 feet.

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[Raymo853]

@Raymo853 130903 wrote:

I’ll be there. Will be headed home to Shirlington via the Key Bridge and Custis is people wish to convoy. Not sure how long I will stay as I tend to get sleepy early.

The route idea: https://www.strava.com/routes/3891229

Reversing my RSVP. Not feeling well and think it is best to ride straight home, rest and not spread sickness around the BAFS community.

[Raymo853]

Name tags? Do we need name tags? I suggest we have them and I have a pack of small ones and sharpies I can bring.

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