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Post by Deleted on Dec 24, 2014 2:37:05 GMT
So a few times my strava distance for a ride has been slightly different to my bike computer and I havent thought much of it..
Today i did my longest ever ride so far. Strava said 26.2 miles, computer said 26.5 miles. Still only 0.3 miles different but hey at my standard you want all you can get. But heres the thing... i was riding with 4 other people and ALL 4 of their stravas agreed perfect with my computer at 26.5 miles dead on.
So is my strava going nutty? Its a samsung s4 mini which happens to beexact same phone as one of the other riders. I mount it on my sleeve in a runners armband pouch (others all use pockets). Cant visually see any break in the route where it may have stopped recording from an initial brief check.
So anyone else had this??
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Post by steg666 on Dec 24, 2014 7:38:26 GMT
I don't have a solution but I also have differences between my cycle computer (cateye padrone) and strava. It's usually by the amounts you mention too, max of 0.5 miles.
The odd part is I think mine has been caused by myself, when I got the cycle computer the shop mounted it and set it all up. It ran perfectly and matched strava identically, even down to top and average speeds being a dead on match. Stupidly I checked the wheels sizes against the cycle computer manual and they were a touch out so I changed the wheel size on the trip computer.
Obviously mine was caused by thinking I knew better than the fella in the cycle shop. I should have just left it alone.
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Post by Radchenister on Dec 24, 2014 7:58:05 GMT
Similar things happen to everyone at one time or another. It flattens out rides for Garmin 200 riders (no altimeter on device), adds time on, has tracking errors on parts of every ride. Strava is Strava though, your device uses a minimum of 4 of the 24 operational satellites orbiting the planet in the vacuum of space, interpolating data via calculating the distance / intersection of large radius circles and tagging it to a time and location in space for transfer relative to mapping information re the planet's surface topography; all for free (mainly). Marvel at the wonder of it all but take it with a pinch of salt I reckon - when I was young the personal communicators on Star Trek were wild fantasy but now we're using something similar, still waiting for teleportation mind .
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Post by jondxxx on Dec 24, 2014 9:12:25 GMT
Marvel at the wonder of it all but take it with a pinch of salt I reckon - when I was young the personal communicators on Star Trek were wild fantasy but now we're using something similar, still waiting for teleportation mind . I always took teleporting with a pinch of salt but am a little disappointed that I can't have a Back to the Future hover board yet
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Post by Deleted on Dec 24, 2014 9:43:27 GMT
Just remember if you are doing a ton and going by Strava to track it that you do an extra mile or 2. Nothing worse than uploading you 100 mile ride to find out strava things it was 99.7 miles.
Strava is never going to be 100%. There are simply too many variables for it to contend with so it will never be as accurate as a 100% calibrated wheel sensor but it's more than good enough for most.
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Post by KiwiBeard on Dec 24, 2014 9:46:43 GMT
I think mostly it depends on how often the gps is polling. Usually 3 seconds, i believe, so if you make a turn at right angle and the polling is greater than 3 seconds, then the line between two points will be the straight line between, not the right angle. Do enough of those and there's your difference.
Sorry, if bit vague and non-understandable, but about to lose the laptop due to batt..
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Post by ChrisD on Dec 24, 2014 9:50:38 GMT
Agree with the cautionary notes expressed by others @alexjm and well done on your longest outing to date. There's an intriguing book called the Physics of Star Trek (easy 2nd hand purchase on eBay) which has a section on the physics of teleportation. Put me right off! I 'like' the occasional additional realism of sci-fi that takes teleportation error into account but it ain't pretty.
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Post by Deleted on Dec 24, 2014 9:53:34 GMT
I think mostly it depends on how often the gps is polling. Usually 3 seconds, i believe, so if you make a turn at right angle and the polling is greater than 3 seconds, then the line between two points will be the straight line between, not the right angle. Do enough of those and there's your difference. Sorry, if bit vague and non-understandable, but about to lose the laptop due to batt.. Very true. Take any ride on strava and zoom in to street level to see the poll points. They be all over the place.
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Post by Deleted on Dec 24, 2014 9:56:30 GMT
Thanks folks the explanations do make sense. I did just wonder if i had a fault or a wrong setting due to the fact it happens every ride yet my four friends all seem to have strava spot on. Seems a bit of a coincidence its always my strava that is wrong/out. Cheers Ps i wonder if the armband interferes with gps, shouldnt. All five rides on the strava map look identical, only the total distance different.
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Post by ianmoss on Dec 24, 2014 10:13:38 GMT
Both use different methods of measuring. GPS measures from tracking your gadget position, computer relies on the turn of your wheel calculating the circumference of your wheel and tyre. Lots of natural anomalies in play. Even tyre pressure could cause a miss read, but only tiny amounts, take the greatest distance!
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Post by jondxxx on Dec 24, 2014 10:41:42 GMT
I think the best you can hope for is consistency. My 'phone app. used to give all sorts of strange results some only achievable with teleportation but the Garmin 200 seems reliable. My neighbour after several runs along a measured mile reckons to have his wired computer accurate to less than a yard. I suspect that wireless versions can be subject to interference from other sources including LED lamp circuitry.
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Post by Deleted on Dec 24, 2014 11:12:32 GMT
I zoomed right in on strava to the very close street view and wow its all over the shop. A lot of my ride passes through buildings and such. Not so much when i zoom into my friends rides.
So i think maybe my gps is off (thus downoaded gps resetter from Google play) or my armband is interfering.
Next ride i will try a gps reset first and see hiw it goes, if still bad will try without armband.
Cheers
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Post by Radchenister on Dec 24, 2014 12:32:57 GMT
Could help; IME, it can go pear shaped in built up areas, vallies / cuttings and in forested routes. It often reads just off the road on hilly terrain (and elsewhere for that matter), sometimes you don't show as riding some segments at all.
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Post by Rocket on Dec 24, 2014 12:57:07 GMT
@alexjm I had the GPS go off a bit on my S3 and a mooch around said to take the back off and tighten all the screws that hold it together. I was sceptical but low and behold it cured my problem with naff GPS ever since. The theory was that the GPS antenna is part of one half and connects to the other half but loose screws make the connection drop signal strength. Try something like GPS Test to see how many satellites you can lock onto and how strong then nip the screws up and try again in exactly the same location.
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Post by Deleted on Dec 24, 2014 17:57:32 GMT
Sounds great Rocket and a bit of earlier googling did show up that and I was sceptical but good to have somebody respected o the forum backing that up thanks. Will try that !!
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