Strava inaccuracies anyone?

jimbob_1978

I think everyone needs to take Strava results with a pinch of salt especially when using mobile phones to record data.

I`ve always had my suspicions but my last ride has just confirmed it.

Was riding with a pal who was using a mobile phone while i have a Bryton GPS unit. He`s a little larger than me so as a consequence he cant climb as well, we hit the bottom of an uphill segment side by side, i changed down a gear he changed up and i sprinted to the top. I was that far ahead i unclipped at the top and waited, yet i had a 10th overall to his 9th!!!!

He`s also very close to me on other segments and ahead of me on another hill climb which he posted on a separate ride. He didn`t single out the segment and his average for the ride was casual at best. On average he`s 1.5 to 2 mph slower than me on most rides.

Maybe they should change Strava to only accept data from stand alone bike units rather than cheapo phones.

Anyone else noticing inaccuracies with riding pals using phones?

Wirral_paul

jimbob_1978 wrote:

I think everyone needs to take Strava results with a pinch of salt

This sentence pretty much sums up Strava.

While i use Strava and upload every ride - the data is too heavily manipulated to have any real meaning. Certain figures are pretty much meaningless (wattage output) etc as they rely on assumptions - like no wind!!

roger_merriman

The argument that Garmins/Bryton are good, phones bad, while I can see why, is something of a red herring.

Plenty of duff data is spat out by devices, GPS's are always going to be iffy for short segments particularly if they have less than great line of sight.

also worth noting that phones get upgraded faster, with newer GPS chips.

Brad123

I had the same with a friend. Raced up a hill stopped and waited for him and strava said he had a better time. Looking closer I stopped before the segment ended. Have a look at were you stopped.

gangxu

I find the Strave App on my iPhone 5 gives competly different elevation info to the Garmin 705, but actual average speeds/distance is pretty similar. On occasions it does go a bit mental though, had one ride where my top speed hit 99mph Still I find it good for judging my own training/performance.

MountainMonster

In my three years on Bike Radar I have never heard of a single person who says Strava is inaccurate :roll:

There needs to be a 'Strava Winge' sticky thread, do people really need to waste space creating new threads for each example?

Wirral_paul

MountainMonster wrote:

I

There needs to be a 'Strava Winge' sticky thread,

It would be bigger than the "big girls" thread!!

rob21

Since Ive been using the Edge 810 i have defo noticed several inaccuracies with elavation TBH

peterberry

my edge 500 is uesless at elevation. at least i get a chance on connect to fix it. i wish strava added this option

ianbar

the other day i had an issue with total climb i did 6 miles further and that was apparently about 1000ft more!! yet that extra mileage was the only difference to the route and no way what so ever was accurate

sloppyschleckonds

I did a ride recently, that I've done before and its 2500ft over 25 miles recorded on garmin edge. One iPhone & one android at the same time recorded 6600ft & 5500ft.

charlie_potatoes

peterberry wrote:

my edge 500 is uesless at elevation. at least i get a chance on connect to fix it. i wish strava added this option

Strava has an elevation correction feature. Its immediately underneath the amount of ft/mtrs climbed on a ride.

Mikey23

Elevation correction is there but also seems a bit random. I use it on flat trail rides and it gives me more and on hilly rides it gives less

I have noticed on a mates new 810 that the climbing seems way OTT. He did a 100 miler with 3 mates all using different garmin types. He had 8000ft, his mates did 5000,5000 and 3000. Makes no sense to me

Mikey23

And it's irreversible so tuf if you don't like it

charlie_potatoes

Mikey23 wrote:

Elevation correction is there but also seems a bit random.

It's by no means perfect I'd agree. What it does though is level the playing field a bit (or would do if everyone used it).
On a club ride it's easy to see who uses it and who doesn't.

I think Strava is great fun but you need a large pinch of salt to go with it.(as mentioned above )

goonz

So basically from this thread, it appears no GPS is accurate, what should I use then???

MountainMonster

Wirral_Paul wrote:

MountainMonster wrote:

I

There needs to be a 'Strava Winge' sticky thread,

It would be bigger than the "big girls" thread!!

Most definitely.

AntD365

Your times on a Strava segments are not measured from the start and end points of the segment but from your closest GPS points to the start and end points, hopefully something they will fix in v3. VeloViewer.com (IIRC) makes and attempt at presenting an alternative leaderboard that takes this in to account.

jimbob_1978

AntD365 wrote:

Your times on a Strava segments are not measured from the start and end points of the segment but from your closest GPS points to the start and end points, hopefully something they will fix in v3. VeloViewer.com (IIRC) makes and attempt at presenting an alternative leaderboard that takes this in to account.

If this is true its a very poor system. And if they do fix this flaw its still gonna leave alot of false and unbeatable segment times after the fix.

charlie_potatoes

jimbob_1978 wrote:

AntD365 wrote:

Your times on a Strava segments are not measured from the start and end points of the segment but from your closest GPS points to the start and end points, hopefully something they will fix in v3. VeloViewer.com (IIRC) makes and attempt at presenting an alternative leaderboard that takes this in to account.

If this is true its a very poor system. And if they do fix this flaw its still gonna leave alot of false and unbeatable segment times after the fix.

I'm sure that it will evolve and improve. Lets not lose sight of the fact that it is free/cheap and (meant to be) FUN

germcevoy

Elevation gain on a 75 mile run yesterday was 2006ft as measured by Strava app running on a Galaxy Nexus. Another rider on the route using a Garmin 305 clocked 3156ft. Massive difference. I also wasn't acknowledged on the segment page on the larger climb but he was (and we rode it side by side). I never expected the phone to be too accurate but over 1000 feet difference is huge.

I think I'll buy a Garmin.

adr82

Germcevoy wrote:

Elevation gain on a 75 mile run yesterday was 2006ft as measured by Strava app running on a Galaxy Nexus. Another rider on the route using a Garmin 305 clocked 3156ft. Massive difference. I also wasn't acknowledged on the segment page on the larger climb but he was (and we rode it side by side). I never expected the phone to be too accurate but over 1000 feet difference is huge.

I think I'll buy a Garmin.

Umm, how do you know the Garmin was any more accurate? The two elevations were totally different, just because the Garmin gave a higher reading doesn't mean it's correct! And before you waste your money, I've used a Garmin 705 and a 500 and they both typically overestimate the amount of climbing I do on a ride. Example from the other day: Garmin 500 claimed 1855ft, Strava elevation correction dropped that to 1451ft. I get a similar result from enabling elevation correction on Garmin Connect. Plotting the route on bikehike.co.uk (which seems to have pretty accurate data) gave me just over 1500ft, so that all indicates the Garmin itself was being a bit generous.

Edit: forgot to say about the segment thing - check out the GPS trace of your ride, it may have been far enough from the road that it didn't register you as riding the whole segment (GPS is a lot less accurate than most people realise). You might be able to sort it out with SNAP

goonz

I used my phone on Sunday and a mate used his Garmin 800. Elevation gained there was a 100ft difference, his Garmin giving the higher reading.

Guanajuato

Strava's elevation 'correction' uses a database of elevation points. If you have a short descent and climb between two points, the strava 'corrects' it to be flat. I vaguely recall the database they use is 90m resolution, possibly augmented with data from saved tracks with elevation data. The database can also be a bit odd around things like trees, bridges and buildings.
As an example, there's a road near here that's around 15-20%. Strava has it as 8% at its steepest. Because the elevation points its using are must be from the buildings and almost terraced areas near the road. Watch stage 2 of this years ToB - its finishing at a flattish bit halfway up the road.
A cycle track along an old railway line on the way in to Lancaster supposedly has a 20% gradient at one point. It does coincide with a point where the line goes over the river on a bridge after being under tree cover. The 2m ramps up could count I suppose.
The Garmin Figure is likely to be more realistic (note I don't say accurate), but GPS alone has a vertical accuracy of about +-100m (it was only ever designed to give a reliable 2D fix), which most garmins augment with air pressure readings. But air pressure varies with time as well as elevation, so not to be trusted entirely.

adr82

Well yes... the short answer to all this stuff is simply that you're not going to get incredibly accurate elevation readings with the sort of typical consumer level hardware/software most people use. Take the various readings as estimates and don't worry about them too much!

goonz

Right, time to contact my mate in NASA and ask him to lend me one of their satellites! Lets see who is more accurate now!