Discussion
OK, proof that Strava recorded on a smart phone is at best 'questionable'.
Looking over some old rides last night and noticed that on a group ride a young lad (16 or 17 at best), not too confident on his bike and not very happy descending at speed had taken a KOM on a local segment with an average of 35mph and a top speed of 50.2 mph. The thing is, on the ride the pack broke into two for this particular stretch of road (only about a mile), some of us going off the front and hitting about 40-ish, then the rest taking a more tempered descent and probably topping out at 30mph max! Looking at his trace I think his phone lost reception for a large chunk of the section then stitched it together giving him an exceptional time, and a top speed of just over 50!
So there you have it folks, don't bother competing with anyone but yourself on Strava because if you do there is every chance that some of the sections you are breaking your neck on can't be bettered unless you are using the Strava app on a phone with dodgy reception!
Looking over some old rides last night and noticed that on a group ride a young lad (16 or 17 at best), not too confident on his bike and not very happy descending at speed had taken a KOM on a local segment with an average of 35mph and a top speed of 50.2 mph. The thing is, on the ride the pack broke into two for this particular stretch of road (only about a mile), some of us going off the front and hitting about 40-ish, then the rest taking a more tempered descent and probably topping out at 30mph max! Looking at his trace I think his phone lost reception for a large chunk of the section then stitched it together giving him an exceptional time, and a top speed of just over 50!
So there you have it folks, don't bother competing with anyone but yourself on Strava because if you do there is every chance that some of the sections you are breaking your neck on can't be bettered unless you are using the Strava app on a phone with dodgy reception!
Raven Flyer said:
Jimbo. said:
MadDad said:
I am sure that the iPhone app gives spurious readings.
There is a chap local to me who seems to rack up dozens of KOM's yet has a relatively low average speed on almost all of his rides, and at best rides 80 miles a week.
He took a KOM riding solo this week on a segment that I rode chaingang a month or so ago with some very accomplished and fast riders. We were breathing through our chamois by the end of this 2 mile segment and only managed to place 4th, yet this chap smashed us riding solo by several seconds.
All of us use Garmins and had exactly the same readings over the section, this chap uses iPhone app - go figure.......
Either he's a weapon who trains smart, or he's a Strava hunter.There is a chap local to me who seems to rack up dozens of KOM's yet has a relatively low average speed on almost all of his rides, and at best rides 80 miles a week.
He took a KOM riding solo this week on a segment that I rode chaingang a month or so ago with some very accomplished and fast riders. We were breathing through our chamois by the end of this 2 mile segment and only managed to place 4th, yet this chap smashed us riding solo by several seconds.
All of us use Garmins and had exactly the same readings over the section, this chap uses iPhone app - go figure.......
MadDad said:
OK, proof that Strava recorded on a smart phone is at best 'questionable'.
Looking over some old rides last night and noticed that on a group ride a young lad (16 or 17 at best), not too confident on his bike and not very happy descending at speed had taken a KOM on a local segment with an average of 35mph and a top speed of 50.2 mph. The thing is, on the ride the pack broke into two for this particular stretch of road (only about a mile), some of us going off the front and hitting about 40-ish, then the rest taking a more tempered descent and probably topping out at 30mph max! Looking at his trace I think his phone lost reception for a large chunk of the section then stitched it together giving him an exceptional time, and a top speed of just over 50!
So there you have it folks, don't bother competing with anyone but yourself on Strava because if you do there is every chance that some of the sections you are breaking your neck on can't be bettered unless you are using the Strava app on a phone with dodgy reception!
Try putting the segment in veloviewer.com or raceshape.com reveals some interesting data like how the distance on the same segment can vary. veloviwer can build alternate leaderboards based on the dataLooking over some old rides last night and noticed that on a group ride a young lad (16 or 17 at best), not too confident on his bike and not very happy descending at speed had taken a KOM on a local segment with an average of 35mph and a top speed of 50.2 mph. The thing is, on the ride the pack broke into two for this particular stretch of road (only about a mile), some of us going off the front and hitting about 40-ish, then the rest taking a more tempered descent and probably topping out at 30mph max! Looking at his trace I think his phone lost reception for a large chunk of the section then stitched it together giving him an exceptional time, and a top speed of just over 50!
So there you have it folks, don't bother competing with anyone but yourself on Strava because if you do there is every chance that some of the sections you are breaking your neck on can't be bettered unless you are using the Strava app on a phone with dodgy reception!
You can raise it with Strava and if it looks dodgy on investigation they remove the match.
HereBeMonsters said:
the1pig said:
After seeing at least 3 power assisted bikes at llandegla today, I'm now very skeptical of any blistering quick times on strava.
There's a bloke who has set +30 mph sector uphill on a route I did the other day. Sooo many people must do this with cars. KOM 82.6kph.
Effin' ridiculous.
There are a couple of reasons I'm aware of why the iphone in particular (and perhaps other smartphones) are likely to throw up oddities:
1) Extrapolation - particularly when it doesn't have a good signal, it tries to 'smooth' / extrapolate the position fixes to make the data less 'noisy'.
2) Timing - the fixes delivered by the API aren't timestamped; the device is doing other stuff in the background, thus there will be some delay in the delivery of the GPS fix to strava. If that's reasonably constant, it's not an issue, but if that is variable (and it is), the strava app doesn't know - it can only take the time of delivery as the time of fix. Over short segments those sort of issues could lead to big differences: Say on entry to a short segment, the phone is 'busy' - it takes a while for the fix to get through.. then it frees up and catches up, taking a few seconds off the run..
The dedicated sat-nav/garmin etc., is only performing one task, and is designed to do that well - I'd expect that the fixes are timestamped early in the process, etc.
1) Extrapolation - particularly when it doesn't have a good signal, it tries to 'smooth' / extrapolate the position fixes to make the data less 'noisy'.
2) Timing - the fixes delivered by the API aren't timestamped; the device is doing other stuff in the background, thus there will be some delay in the delivery of the GPS fix to strava. If that's reasonably constant, it's not an issue, but if that is variable (and it is), the strava app doesn't know - it can only take the time of delivery as the time of fix. Over short segments those sort of issues could lead to big differences: Say on entry to a short segment, the phone is 'busy' - it takes a while for the fix to get through.. then it frees up and catches up, taking a few seconds off the run..
The dedicated sat-nav/garmin etc., is only performing one task, and is designed to do that well - I'd expect that the fixes are timestamped early in the process, etc.
Raven Flyer said:
A car driven at just the right speed, using the Strava app, will get you KOM anywhere you want. Unless a KOM has cadence or HR, I don't believe it.
Even then, don't be too sure.. google 'digitalepo' 
I run Strava on my iPhone 4. It sits in my back pocket on a ride. I use a Cateye computer for speed and distance etc. At the end of a ride the distances between the two always match. The moving time is always different, probably due to the way Strava retrospectively works it out. Maybe as all my rides are in the country, the phone always has a good GPS signal?
It was interesting after the PH cycling weekend how even the Garmin devices recorded lots of different elevation gains!
Ateve
It was interesting after the PH cycling weekend how even the Garmin devices recorded lots of different elevation gains!
Ateve
Got my second (albeit joint) KOM for a climb this evening. This was part of a short ride (15 miles) so is does feel like I'm cheating a bit, but hey!
http://app.strava.com/activities/58199281#10772881...
http://app.strava.com/activities/58199281#10772881...
MadDad said:
I am sure that the iPhone app gives spurious readings.
There is a chap local to me who seems to rack up dozens of KOM's yet has a relatively low average speed on almost all of his rides, and at best rides 80 miles a week.
He took a KOM riding solo this week on a segment that I rode chaingang a month or so ago with some very accomplished and fast riders. We were breathing through our chamois by the end of this 2 mile segment and only managed to place 4th, yet this chap smashed us riding solo by several seconds.
All of us use Garmins and had exactly the same readings over the section, this chap uses iPhone app - go figure.......
With a 40mph tailwind, you can hold 35mph on a tiny downhill for a mile or two, 40mph headwind, forget about even 20mph...I don't think the measuring device was the only variable.There is a chap local to me who seems to rack up dozens of KOM's yet has a relatively low average speed on almost all of his rides, and at best rides 80 miles a week.
He took a KOM riding solo this week on a segment that I rode chaingang a month or so ago with some very accomplished and fast riders. We were breathing through our chamois by the end of this 2 mile segment and only managed to place 4th, yet this chap smashed us riding solo by several seconds.
All of us use Garmins and had exactly the same readings over the section, this chap uses iPhone app - go figure.......
I don't get it. My phone seems to give very similar readings to friends' garmins. I'm only "playing" the strava game for fun, it's not a race, but it is a great motivator.
Dizzee - Know what you mean about Strava knocking your average speed and elevation down. It has always done it, but at lease 0.3mph for soem reason. yet when you upload to Garmin Connect it matches the Garmin. Odd indeed, but it just means you have to go 0.3mph faster :lol:
Also, the current challenge leader is now at 900 ish km which is alot, but certainly possible. I guess that 5,000km chap was an error which has since been removed.
Also, the current challenge leader is now at 900 ish km which is alot, but certainly possible. I guess that 5,000km chap was an error which has since been removed.
Dizeee said:
And still not understanding the challenges.
Day 4 of the month, leader = 5,489.6 km in 4 days.
So thats about 1450 a day. Whats that about 900 miles a day? Every day, for 4 days? It doesn't make sense.
Some stupid mileages popping up on junedoggle, either someone hopped on a plane or digitalepo'd it, hopefully they'll get deleted.Day 4 of the month, leader = 5,489.6 km in 4 days.
So thats about 1450 a day. Whats that about 900 miles a day? Every day, for 4 days? It doesn't make sense.
500k was my goal for the month, signing to strava means i'm gonna chase 750, so I'm only interested in that not some supurious 15000k in 4 day idiot.
I genuinely couldn't care less if someone has got 5,000km in 4 days. I'm surprised anyone does - or maybe it's just being pointed out to demonstrate the suspect elements of the platform? I use Strava to track my performance, though I did get a KOM yesterday, so I'll be put out if someone digital EPO's that . But the challenges, your competing against thousands across the globe; in this case 60k or so.
. But the challenges, your competing against thousands across the globe; in this case 60k or so.Well, seems Strava ain't faultless.
Did a 10 mile official TT tonight, timed et al.
Mate of mine started 1 minute behind me. We both did the 10 mile course no issues.
As I am finishing my mate is not too far behind, and as I turn arounf having finished I see him end, and as he finished around 30 seconds after me, yet started a minute later, I tell him he is looking at a time around 30 seconds quicker.
This is confirmed when the results sheet appears, I finish 24:49 and he finishes around 30 seconds earlier.
We then both upload to Strava.
The results are very different. Strava has me at my correct time - 24:49 (which I was impressed with the accuracy as I started it as I started and ended when I ended). It however has him at 25:41, and a few places down.
Both are today's date, both are fresh Garmin data and it even has us riding together as you would expect. I have spent all night trying to work it out, and can't.
It picked up the TT segment so he has not shortcutted it. He was timed by a human as was I, and I know he was quicker as I saw him finish just after I did despite setting off later.
It seems, Strava has failed here.
Did a 10 mile official TT tonight, timed et al.
Mate of mine started 1 minute behind me. We both did the 10 mile course no issues.
As I am finishing my mate is not too far behind, and as I turn arounf having finished I see him end, and as he finished around 30 seconds after me, yet started a minute later, I tell him he is looking at a time around 30 seconds quicker.
This is confirmed when the results sheet appears, I finish 24:49 and he finishes around 30 seconds earlier.
We then both upload to Strava.
The results are very different. Strava has me at my correct time - 24:49 (which I was impressed with the accuracy as I started it as I started and ended when I ended). It however has him at 25:41, and a few places down.
Both are today's date, both are fresh Garmin data and it even has us riding together as you would expect. I have spent all night trying to work it out, and can't.
It picked up the TT segment so he has not shortcutted it. He was timed by a human as was I, and I know he was quicker as I saw him finish just after I did despite setting off later.
It seems, Strava has failed here.
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