Strava.com - Put your money where your mouth is

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Blandiblub
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Re: Strava.com - Put your money where your mouth is

Postby Blandiblub » Fri Sep 21, 2012 11:47 am

mudcovered wrote:
Blandiblub wrote:Ta. Weirdly, I've also noticed that the 'total number of rides' in the Android Strava app is decreasing! I thought I was going mad but did my ride home yesterday as usual and my total rides went from 17 to 16! (only recently started using it...). I've just totted up the individual rides shown and it's 22. :/


Thats because its actually total rides in the last 28 days (look at the text above the count. ;) ).

There is a year to date total rides a bit further down.

Mike


Ho ho! Shows how much attention I pay that page - just focussing on the big numbers clearly! Many thanks for that - silly me...
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Pufftmw
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Re: Strava.com - Put your money where your mouth is

Postby Pufftmw » Fri Sep 21, 2012 13:29 pm

:evil: Grrrrr :evil:

I gained a KOM on "Old Kent Road" last week - 24secs @ 37.1mph http://app.strava.com/rides/21940922

Looking at my KOMs to see how many Big Mat or others might have nicked this week, I see its missing, so I check and see that although that activity and the KOM are still reported on the ride, I'm now 34th or somesuch on the segment page :(

What's all that about then? Someone reported it as too fast? It can't be dangerous as you can still see people's times. There's a couple of 33mphs there, so I'm not that far removed, just faster :D

Not happy that my trace for that segment has been removed for some reason - KOMs are hard enough to get at my age as it is!

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dhope
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Re: Strava.com - Put your money where your mouth is

Postby dhope » Fri Sep 21, 2012 14:07 pm

Looks like a dodgy average. 12 seconds to get to 37, held for a second and tailed off a bit to 34. Still bleedin' quick, but not an average of 37mph, so assume the KOM's been removed but a new average not calculated.
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BigMat
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Re: Strava.com - Put your money where your mouth is

Postby BigMat » Fri Sep 21, 2012 14:37 pm

Is that the one at the start of Old Kent Road? Might have a crack this evening, think 28s my best so far but is tricky with traffic / lights. 24s is ruddy quick, maybe Strava picked up a glitch or maybe somebody flagged it? If the latter, might be worth emailing them to get flag removed?

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Pufftmw
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Re: Strava.com - Put your money where your mouth is

Postby Pufftmw » Fri Sep 21, 2012 15:02 pm

Its to do with maths Dunc

The distance to be travelled is just under .25 miles (the segment) and at the time taken to do the segment is 24 seconds. Ergo...( & keeping the numbers even), the time taken to do 1 mile is 96 seconds (multiply by 4), which implies that the speed is 60/(96/60) = 37.5mph. Distance/time taken = average.

Use the same methodology for the couple of people at 27 seconds and it works out as 33.3 mph (obv the distance is a bit under .25 hence the extra .3 of a sec)

The reason is that at a higher speed, you will cover a greater distance every second, so although I only hit 37 for 4 or 5 seconds, I travelled a lot further to someone that started the segment at a higher pace but maintained a steady pace throughout.

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BigMat
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Re: Strava.com - Put your money where your mouth is

Postby BigMat » Fri Sep 21, 2012 15:13 pm

This is probably relevant here (taken from veloviewer):

Alternative Segment Leaderboard
Only works for "popular" segments (those that appear in your ride achievements without having to "unhide" them) due to the way the Strava API works.

Please note: This page is purely for an academic type interest and isn't intended to imply that it is a more accurate leaderboard than that shown by Strava, it is just a different way of looking at the stats. In fact, the longer and wigglier the segment then the less accurate this alternative leaderboard will quickly become as it doesn't take into account any gps drift. The specific type of segment that this alternative leaderboard MIGHT provide a more accurate leaderboard for are those that are fairly short (less than 1km), in a straight line and with very good satellite visibility (hence, little to no gps drift) in which case the differences in distance between riders is most likely down to the difference between the start/end points of their segment (which currently can vary enough to affect the leaderboards of these specific type of segments). Unless you and your mates have got your Math heads on then don't expect them to listen to you when you tell them you were actually faster than them on a segment! I'm reliably informed that Strava will be updating their segment matching algorithm at some point to remove these varying start/end points and so provide a more accurate leaderboard for these types of segments. If they apply that retrospectively though then there might be a bit of outrage at people loosing their KOMs.


Bumps me up a place to 3rd. :D

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Pufftmw
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Re: Strava.com - Put your money where your mouth is

Postby Pufftmw » Fri Sep 21, 2012 15:33 pm

Can't work out why it bumps you up to 3rd?! I think my reasoning still stands though - difference between 2 points was 24 secs, but...

Looking at my whole trip again, I see that whereas I posted a KOM in Old Kent Road, an 8th Overall on OKR southbound sprint (I shouldn't have backed off LOL) and a 2nd Overall down Loampit Hill (I took 3 secs back against your KOM Mat to just 1 behind), none of those times are now displaying :evil: :evil: :evil: :evil:

More than slightly hacked off as I put a lot of hard work into getting the KOM & 2nd. Even Amersham Way was 36 seconds, so respectable. The fact that it all the data has just been "removed" without checking with me or even notifying me, is naughty. If I had been cheating, manually editing tpx files or driving a car, then fine but that was honest and hard pedalling :evil: :evil: :evil:

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Re: Strava.com - Put your money where your mouth is

Postby UndercoverElephant » Fri Sep 21, 2012 15:34 pm

Pufftmw wrote:The reason is that at a higher speed, you will cover a greater distance every second, so although I only hit 37 for 4 or 5 seconds, I travelled a lot further to someone that started the segment at a higher pace but maintained a steady pace throughout.


But surely given that you only hit 37 for 4-5 seconds, and the rest of the time you were SLOOOOW, that ought to preclude you from claiming a 37mph average for a segment?

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Re: Strava.com - Put your money where your mouth is

Postby BigMat » Fri Sep 21, 2012 15:37 pm

Sounds like you've been flagged - its pretty instantaneous. I have flagged a couple of very obvious car / motorbike rides and they are taken down immediately. I have also had rides of mine flagged I think - lost an old KOM on Amersham Way (which I have since bettered anyway) - its a bit rude not to give the "flagee" a right of reply.

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Re: Strava.com - Put your money where your mouth is

Postby Pufftmw » Fri Sep 21, 2012 15:41 pm

UndercoverElephant wrote:
Pufftmw wrote:The reason is that at a higher speed, you will cover a greater distance every second, so although I only hit 37 for 4 or 5 seconds, I travelled a lot further to someone that started the segment at a higher pace but maintained a steady pace throughout.


But surely given that you only hit 37 for 4-5 seconds, and the rest of the time you were SLOOOOW, that ought to preclude you from claiming a 37mph average for a segment?


Maths :roll:

:P

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Re: Strava.com - Put your money where your mouth is

Postby Pufftmw » Fri Sep 21, 2012 15:45 pm

BigMat wrote:Sounds like you've been flagged - its pretty instantaneous. I have flagged a couple of very obvious car / motorbike rides and they are taken down immediately. I have also had rides of mine flagged I think - lost an old KOM on Amersham Way (which I have since bettered anyway) - its a bit rude not to give the "flagee" a right of reply.


Indeed but using a Garmin with a Cadence sensor and an HRM ought to show that a certain amount of EFFORT was being put into the segement (consistent with a 47 yo heart) and I wasn't just w@nking in the back of the car to get my HR up :roll:

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Re: Strava.com - Put your money where your mouth is

Postby UndercoverElephant » Fri Sep 21, 2012 15:50 pm

Pufftmw wrote:
BigMat wrote:Sounds like you've been flagged - its pretty instantaneous. I have flagged a couple of very obvious car / motorbike rides and they are taken down immediately. I have also had rides of mine flagged I think - lost an old KOM on Amersham Way (which I have since bettered anyway) - its a bit rude not to give the "flagee" a right of reply.


Indeed but using a Garmin with a Cadence sensor and an HRM ought to show that a certain amount of EFFORT was being put into the segement (consistent with a 47 yo heart) and I wasn't just w@nking in the back of the car to get my HR up :roll:


Pssst! Wanna go on Puff's turbo-trainer in the back of a van? :lol:

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Re: Strava.com - Put your money where your mouth is

Postby dhope » Fri Sep 21, 2012 15:53 pm

Pufftmw wrote:Its to do with maths Dunc

The distance to be travelled is just under .25 miles (the segment) and at the time taken to do the segment is 24 seconds. Ergo...( & keeping the numbers even), the time taken to do 1 mile is 96 seconds (multiply by 4), which implies that the speed is 60/(96/60) = 37.5mph. Distance/time taken = average.

Use the same methodology for the couple of people at 27 seconds and it works out as 33.3 mph (obv the distance is a bit under .25 hence the extra .3 of a sec)

The reason is that at a higher speed, you will cover a greater distance every second, so although I only hit 37 for 4 or 5 seconds, I travelled a lot further to someone that started the segment at a higher pace but maintained a steady pace throughout.

:wink: Yep, gathered it was about maths, ta. My observation was just from glancing at the graph and assuming that there's some strange estimation going on.
If the average is 37.1mph and the peak speed is 37.2mph, which you held for 4 seconds, then the average for the remaining 20 seconds would be around 37.08... and... it aint.

Not saying it wasn't honest or wasn't bleedin' quick, just that I glanced at the graph and thought that there had been some strange maths if Strava were trying to match the two together
Last edited by dhope on Fri Sep 21, 2012 16:01 pm, edited 1 time in total.
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Re: Strava.com - Put your money where your mouth is

Postby Clever Pun » Fri Sep 21, 2012 15:55 pm

I hate that Amersham way segment, I've not managed a balls out go yet, but some pretty reasonable attempts and I'm not in the top 10

not happy... Still trying to figure out all the segments on that route still
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Re: Strava.com - Put your money where your mouth is

Postby Pufftmw » Fri Sep 21, 2012 16:20 pm

It is my bette noire - the amount of times I've dug deep and found the lights red or traffic at the top, I daren't think about. I've maybe got a couple of secs more in me for that one but fully expect you to sail past my best time in due course! Go back to going the way you used to go!!!

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Re: Strava.com - Put your money where your mouth is

Postby Clever Pun » Fri Sep 21, 2012 16:51 pm

Pufftmw wrote:It is my bette noire - the amount of times I've dug deep and found the lights red or traffic at the top, I daren't think about. I've maybe got a couple of secs more in me for that one but fully expect you to sail past my best time in due course! Go back to going the way you used to go!!!


No :lol: , so many new segments to attack on this route just waiting for good legs and traffic free roads to converge then maybe

I was a bit surprised to get top 10 for the lewisham downhill segment on fixed... little hairy at the bottom that one
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Re: Strava.com - Put your money where your mouth is

Postby Clever Pun » Fri Sep 21, 2012 16:54 pm

I've just seen why I can't get top ten, the finish is further than I thought, so I'm letting off the gas way too early
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Re: Strava.com - Put your money where your mouth is

Postby adr82 » Fri Sep 21, 2012 20:48 pm

Pufftmw wrote:Its to do with maths Dunc

The distance to be travelled is just under .25 miles (the segment) and at the time taken to do the segment is 24 seconds. Ergo...( & keeping the numbers even), the time taken to do 1 mile is 96 seconds (multiply by 4), which implies that the speed is 60/(96/60) = 37.5mph. Distance/time taken = average.

Use the same methodology for the couple of people at 27 seconds and it works out as 33.3 mph (obv the distance is a bit under .25 hence the extra .3 of a sec)

The reason is that at a higher speed, you will cover a greater distance every second, so although I only hit 37 for 4 or 5 seconds, I travelled a lot further to someone that started the segment at a higher pace but maintained a steady pace throughout.

That's not right. For a start unless you know the exact length of the segment (I'm sure it isn't 0.25 or 0.2 miles exactly) you can't calculate speed accurately this way. If the length you're using is too short the speed will end up being too high.

More importantly, you can't rely on Strava to work this out for you, it is terrible at dealing with this type of short, high-speed segment! I don't know what the hell they're doing to come up with some of their times but on many occasions I've been given average speeds 3-5mph faster than what I know was my real top speed on similar segments. The speed graph from your attempt here clearly shows there was no way you could have averaged over 37mph since you were only at that speed for 2-3 seconds.

Try this: click and drag from one end of the graph to the other, the same way as if you were selecting a part of a longer ride. Strava will report the average speed again, but this method apparently uses a different method of calculating the result and the average speed now comes out as 34.5mph (assuming that's accurate and keeping 24s time, then the segment must be around 0.23 miles long, which seems reasonable enough).

From looking at the other results you would still have beaten everyone else even at 34.5mph though! Perhaps your ride was flagged because someone else noticed the 37.5mph average wasn't accurate, I wouldn't be surprised...

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Re: Strava.com - Put your money where your mouth is

Postby pastryboy » Fri Sep 21, 2012 21:26 pm

The short sections on strava are a waste of time - they just don't track properly and seem to be in three second chunks.

I've got a KOM with an average speed of 34.5mph but if you look at the performance graph I never went above 25.9mph. The performance graph also shows that I went from 9.7mph to 25.9mph instantly which obviously isn't right.

There's another segment that ends with at tunnel - I go at it holding high 20's which strava shows but right at the tunnel entrance it always shows me at 8mph or thereabouts for the last few seconds meaning I can't get anywhere near the top of the leaderboard.

I used to delete the ride if I got a KOM I didn't I should have got but now I can't be bothered.

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Re: Strava.com - Put your money where your mouth is

Postby Pufftmw » Mon Sep 24, 2012 09:13 am

Sorted :)

Thanks Strava

I agree that the av is prob too high for the measured distance but it will put everyone in the same boat.


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