GPS Distance errors
06-09-21 | 10:50 AM
#101
Senior Member
Joined: Sep 2007
Posts: 15,263
Likes: 1,763
From: Far beyond the pale horizon.
In this thread:
You posted this nonsense a mere 3 hours after whining about it!
It was "once" today in this thread. Across the entire thread, it was 7 or 8 times!
Last edited by njkayaker; 06-09-21 at 11:10 AM.
06-09-21 | 03:04 PM
#102
Senior Member
Joined: Jul 2006
Posts: 9,158
Likes: 1,743
From: Lebanon (Liberty Hill), CT
Bikes: Canyon Aeroad, CAAD 12, MASI Gran Criterium S, Colnago World Cup CX, Guru steel & Guru Photon
There's an article in Bicycling that has some information why there are GPS errors, and what you can do to avoid them:
How Your GPS Lies to You
How Your GPS Lies to You
06-10-21 | 08:28 AM
#103
Senior Member
Joined: Jun 2015
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From: North Central Wisconsin
06-10-21 | 09:50 AM
#104
Senior Member
Joined: Sep 2007
Posts: 15,263
Likes: 1,763
From: Far beyond the pale horizon.
https://www.dictionary.com/browse/whiny
complaining; fretful; cranky:The baby is whiny because he missed his nap.
06-10-21 | 09:51 AM
#105
Senior Member
Joined: Sep 2007
Posts: 15,263
Likes: 1,763
From: Far beyond the pale horizon.
https://www.dictionary.com/browse/whiny
complaining; fretful; cranky:The baby is whiny because he missed his nap.
Last edited by njkayaker; 06-10-21 at 09:56 AM.
06-10-21 | 10:14 AM
#106
Perceptual Dullard
Joined: Sep 2009
Posts: 2,916
Likes: 1,754
A few weeks ago Jan Heine had a post on his blog about the aero drag of handlebar bags. He was using max speed while coasting down a big hill to determine that. We were curious about that and asked him how he was measuring speed: he was using an iPhone rather than a wheel sensor. If you looked at this max speed, you could tell it was anomalously noisy. We pointed this out and suggested that if he wanted to continue to use max speed (which isn't really that good of a metric, but it was what he was using) he should switch to a wheel sensor. This is about when he decided to cut off comments on his blog posts.
06-10-21 | 03:07 PM
#107
Senior Member
Joined: Jul 2009
Posts: 8,151
Likes: 11,091
Bikes: Colnago, Van Dessel, Factor, Cervelo, Ritchey
A few weeks ago Jan Heine had a post on his blog about the aero drag of handlebar bags. He was using max speed while coasting down a big hill to determine that. We were curious about that and asked him how he was measuring speed: he was using an iPhone rather than a wheel sensor. If you looked at this max speed, you could tell it was anomalously noisy. We pointed this out and suggested that if he wanted to continue to use max speed (which isn't really that good of a metric, but it was what he was using) he should switch to a wheel sensor. This is about when he decided to cut off comments on his blog posts.
05-25-23 | 08:57 AM
#111
aged to perfection
Joined: Jun 2009
Posts: 2,242
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From: PacNW
Bikes: Dinucci Allez 2.0, Richard Sachs, Alex Singer, Serotta, Masi GC, Raleigh Pro Mk.1, Hetchins, etc
about halfway down in this thread we did a pretty good discussion of "how GPS works"
How much accuracy do you demand from your bike computer? - Page 2 - Bike Forums
worth a read with some technical details of GPS internals.
your computer is calculating a waypoint every second and then "stitching" those points together to derive speed and distance
the computer does "snap" the position to a road because the raw GPS waypoint has a circular error of about 15 feet best case.
so there are a variety of errors that are possible
worth a read
/markp
How much accuracy do you demand from your bike computer? - Page 2 - Bike Forums
worth a read with some technical details of GPS internals.
your computer is calculating a waypoint every second and then "stitching" those points together to derive speed and distance
the computer does "snap" the position to a road because the raw GPS waypoint has a circular error of about 15 feet best case.
so there are a variety of errors that are possible
worth a read
/markp
