[Closed] Strava Measurements

I think its generally accepted that vertical measurement by GPS is not as accurate as latitude/longitude. So metres climbed is going to vary between devices that record GPS data.

Over what distance was the route ?

An assumption based guess is that the Audax UK data was likely taken on well-specced dedicated GPS device (Garmin etc) and your phone is a non-dedicated GPS device that really only needs GPS data to find a point on a map.

Was that after uploading to STRAVA? When you upload I thought STRAVA anchored you route to a base map to get more accurate elevation. Could the AUK just be total of the significant climbs measured from a paper map?

I think the problem in the end is that every method yields a different result. A device that you carry that works with 100% accuracy will record more ascent than one based on say 10m contours

Yes, Strava corrects the altitude unless it was recorded on a device with a barometric altimeter, which is the "best" way to record elevation changes (seems to work for aircraft, and I think it's important for them!).

Sometimes the Strava one takes a short while to be corrected from what you actually recorded.

If you recorded it on an iPhone, that does have a barometric altimeter built into it (though I'm not 100% certain that it is used when Strava is recording) so I suppose it is possible that your reading could be "more" accurate than the AUK one.

Depends what you used to measure it

My accident damaged 5S tends to smooth stuff out both in terms of distance and elevation. My 7 was terrible at first it used to jitter all over the place and record about 10% higher than the 5 on the same route. The most recent iOS update has improved the 7 although it still reads more than the 5 which is roughly in agreement with my Garmin 🙂

HTH

GPS Elevation is crap, there's a huge difference between the elevation I get using my Edge 810 and my FR235 on my commute (about 1100ft vs 650ft) the watch doesn't have a barometric altimeter. I'd get one with if I was using it regularly for riding.

Erm - no, there is no barometric altimeter in any released iPhone.

Rachel

Strava accuracy can be all over the place. I've had rides where I started and finished at exactly the same time as a mate and there's been a 20 sec difference in our strava times, I've also add ascent variations of hundreds of metres.

[quote=allthegear ]Erm - no, there is no barometric altimeter in any released iPhone.
Rachel

there has been one in there since the iphone 6.

My iPhone (5s since you ask) consistently over estimates the distance with Strava.
I've been out on multiple rides with a friend who uses a Garmin, and over a 25 mile ride my iPhone will record about 1 mile more in distance than his Garmin.

Good for my yearly stats, but slightly annoying accuracy-wise!

barometric altimeter, which is the "best" way to record elevation

Only if it's set accurately!

I think DC Rainmaker did some accuracy testing of various GPS units over on his site

The route was according to AUK 2400 metres of climbing over 100K.

My legs are convinced that it was 2400 metres! I just have an android phone app on my Samsung phone.

I would think AUK are quite obsessive about these things.

@allthegear - Oh yes there is - I'm using it right now on my work iPhone 6!

e.g. link to a pilot website about it - http://ipadpilotnews.com/2014/10/use-iphone-6-backup-altimeter/

I don't follow iPhone developments as I hate the damned things, but I know I've got on this on my work phone - I can tell you at the moment the pressure in my office 1022.30 hPa, which is what my iPhone is telling me!

@nickc - whether it is set correctly or not is irrelevant for measuring total ascent / descent during an individual ride. Yes, it will have the starting elevation incorrect, but every metre you climb or descend from that point will be accurately recorded. Having said that, keeping it calibrated so that whenever you dig it out of your pocket it properly records your elevation is a faff, but something that pilots have to cope with doing before every flight etc.

Traditionally, the climb for audaxes is based on counting contour lines on an OS map.

Though I think nowadays, it can be based on GPS. Though it has to be calculated using the official software, which can process the GPS track in the right way.

I stand corrected!!

Rachel (breaking every STW tradition)

Well, to open another can of worms try this. Do a hilly road ride, then create the same route on strava and check out the difference on altitude measured between the two. Sometimes i get up to a 200 metre difference over a 60k ride. Created route always gives more altitude.

My iPhone (5s since you ask) consistently over estimates the distance with Strava.
I've been out on multiple rides with a friend who uses a Garmin, and over a 25 mile ride my iPhone will record about 1 mile more in distance than his Garmin.

Depending on the Garmin it might well be that your phone is more accurate

This guy seems ti think the i phone 5s is better than every Garmin watch he has tested

http://fellrnr.com/wiki/GPS_Accuracy

I still havent forgiven strava for cheating me out my only 'proper'kom.

5 mile flat section on the road, used by loads of roadies. Was at my fittest with a pal and a decent wind behind so we both went for it, basically taking turns up front and burying ourselves in search of glory.

I started behind him and finished about 10 yards ahead yet he took top spot on the leaderboard by 6 seconds!! Wtf!

Only other kom I own is a 200 yard dash past the local chinese takeaway between 2 sets of lights. Given my average of 35 mph and I usually roll down that stretch I can only think I left the gps running on the drive back home

Strava regularly underestimates my performance by 60-70%. I correct it though with d-epo