tag:blogger.com,1999:blog-5082954078864845206.post1483302726073966765..comments2024-03-17T10:39:40.056-04:00Comments on Hill Junkie: On GPS Units and MP3 PlayersHill Junkiehttp://www.blogger.com/profile/01901432169252097296noreply@blogger.comBlogger12125tag:blogger.com,1999:blog-5082954078864845206.post-62465552805431554292013-11-05T16:22:28.263-05:002013-11-05T16:22:28.263-05:00I like precise data and therefore continue to use ...I like precise data and therefore continue to use wired cycle computers. I doubt they will ever completely go away.Jasonhttps://www.blogger.com/profile/05814447937394114176noreply@blogger.comtag:blogger.com,1999:blog-5082954078864845206.post-80971381991202782012-08-06T20:25:29.043-04:002012-08-06T20:25:29.043-04:00MKR - I hear ya on not getting credit for your eff...MKR - I hear ya on not getting credit for your efforts. Only deal is, in two rides, my sensor stopped working! Argh! I'm borderline removing all metrics devices as AK hinted.<br /><br />MJC - I've seen some pretty bizarre Strava behavior, as many have. You can actually deviate a long way off a segment and come back to it, and still get credit as doing it. I assume this works both ways, Hill Junkiehttps://www.blogger.com/profile/01901432169252097296noreply@blogger.comtag:blogger.com,1999:blog-5082954078864845206.post-65846956166136579822012-08-06T17:19:26.819-04:002012-08-06T17:19:26.819-04:00For what it's worth, some types of GPS error (...For what it's worth, some types of GPS error (notably undermeasurement on trails) doesn't really affect Strava segment competition since leaderboards are ranked by time and not average speed. With segments, the GPS data is really only used for 2 things:<br /><br />(1) recognizing a segment<br />(2) determining the elapsed time<br /><br />You can have a track with tons of error, but so MJCnoreply@blogger.comtag:blogger.com,1999:blog-5082954078864845206.post-30602407604165362462012-08-06T15:41:07.272-04:002012-08-06T15:41:07.272-04:00We just started using Ant+ sensors for the GPS on ...We just started using Ant+ sensors for the GPS on the MTBs as well. Sick of running redundant devices and having Strava devalue your efforts :)mkrhttps://www.blogger.com/profile/15780870344676828580noreply@blogger.comtag:blogger.com,1999:blog-5082954078864845206.post-88737166350506998862012-08-06T13:11:06.988-04:002012-08-06T13:11:06.988-04:00If you want to see a good demonstration of the ina...If you want to see a good demonstration of the inaccuracies of GPS, pick a small (< 5mi) single-track loop and do multiple laps. It can vary to a very surprising degree. The forest canopy is known to create problems with the GPS signal. On top of that, if you add different GPS units to the mix it can become even more variable. Without post-processing of the GPS data against values from a Markhttp://singlespeedslog.wordpress.comnoreply@blogger.comtag:blogger.com,1999:blog-5082954078864845206.post-56865102924929351622012-07-31T12:11:08.132-04:002012-07-31T12:11:08.132-04:00Right on AK!Right on AK!CB2https://www.blogger.com/profile/01024419369112347720noreply@blogger.comtag:blogger.com,1999:blog-5082954078864845206.post-54002873092022264592012-07-31T11:49:30.971-04:002012-07-31T11:49:30.971-04:00Doug, I think this is why we should all take the S...Doug, I think this is why we should all take the Strava stuff with a grain of salt. I regularly ride with people who have various degrees of GPS instrumentation and we always have conflicting results, on the magnitudes of which you write about. Cycling is a sport where people get scientifically meticulous about counting grams and measuring this and that, but we shouldn't loose sight of the AKhttps://www.blogger.com/profile/03215582446274467931noreply@blogger.comtag:blogger.com,1999:blog-5082954078864845206.post-53831908001485566242012-07-31T09:44:45.628-04:002012-07-31T09:44:45.628-04:00Ah, now I see why CB2 is hooking up the GSC.. Pro...Ah, now I see why CB2 is hooking up the GSC.. Problem is when I upload off-road track to Strava while using speed sensor, it ignores it and uses GPS. This is also why I question the credibility of data uploaded via phone apps.Mookiehttps://www.blogger.com/profile/13291973377203391109noreply@blogger.comtag:blogger.com,1999:blog-5082954078864845206.post-81783665492448785462012-07-31T08:08:47.057-04:002012-07-31T08:08:47.057-04:00I've run my 500 and 305 simultaneously; the 30...I've run my 500 and 305 simultaneously; the 305 recorded a higher mileage despite being in my pocket (the 500 was on my stem).CB2https://www.blogger.com/profile/01024419369112347720noreply@blogger.comtag:blogger.com,1999:blog-5082954078864845206.post-74959644598589286212012-07-30T22:07:16.978-04:002012-07-30T22:07:16.978-04:00Rami - that doesn't account for why commercial...Rami - that doesn't account for why commercial GPSs so undermeasure distance. My GPS knows I'm walking 2.5mph, but if I walk in a small circle, it just doesn't measure much distance. You'd think Garmin and others would be able to do a better job integrating that velocity vector, which can be determined very accurately, to get better distance. These things never over measure. ThereHill Junkiehttps://www.blogger.com/profile/01901432169252097296noreply@blogger.comtag:blogger.com,1999:blog-5082954078864845206.post-14074977680390541372012-07-30T21:10:55.026-04:002012-07-30T21:10:55.026-04:00I'd bet if you did another test you'd find...I'd bet if you did another test you'd find your 500 GPS is far less accurate then your 705 GPS. Using GPS measurement for both (no wheel sensors) I have both, and the 500 is useless for singletrack distance measurement. My 705 usually measures about 10% less distance than a wired Cateye I have. The 500 is more like 20-25% Not sure why, from my research both units supposedly use the same Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-5082954078864845206.post-90896766502291701842012-07-30T20:58:06.608-04:002012-07-30T20:58:06.608-04:00Doug, I believe the restriction on GPS accuracy is...Doug, I believe the restriction on GPS accuracy is intentional per (take a guess) government regulations. Civilian GPS units only have access to Coarse/Acquisition (C/A) code. This may have up to 20m error. Meanwhile, the Precision (P) code, reserved for military use, can get very high accuracy, close to within 1m.Raminoreply@blogger.com