Silly STRAVA Racing

[smutchin]

Pretty good day today:
1x KOM
2x 2nd overall
Several top 10s

I'm just 4 seconds behind the KOM on both those 2nds, which is promising - I was weighed down by a full saddlebag today...

d.

 

[Hacienda71]

Right in the last couple of days, I have nailed Katie Price's Angry Lobster and I have Smelt the Bacon but I am not sure I want to go here

 

[smutchin]

Not only do we not have any proper hills down here in the south, our Strava segments have rubbish names too.

d.

 

[400bhp]

KoM's for me are like painting the forth bridge at the moment.

As soon as I get one I lose another.

I now have a list of about 10 where I will try to regain KoM, but will do so in my own time, when conditions (and conditioning) allow.

 

[HLaB]

I had forgotten I'd set a KOM on this segment I'd set on the cheap heavy SS with flat pedals, somebody came along today and smashed it. Lol, it looks like he diverted a good ride just so he could get the segment and a couple of others. Mind you its not as extreme as this one, lol.

 

[potsy]

Set a PR on the hotly fought segment 'brinny hill' last night, have moved up a place to 13th

 

[Ben Lowe]

Hi all, First off thanks for the links to StravaViewer on here. Glad to see some people are making use of it!

Just added a cool new feature that allows you to graphically display all your Strava segments and interactively change all the axis and filter the data. I'm hoping this will be a useful training tool to allow you to compare your efforts and see where you could do better (against yourself as well as others). I've put in some pre-sets to give you an idea of how to use the options. Have a look at my dashboard if you're not on the list (yet) yourself to get an idea as to what I mean. Still work in progress though and performance isn't the best on iPads and phones (Google charts don't work on Android at all).

There are a few pro riders on the list just as a way of comparison (in case you thought your stats were half-way impressive): Taylor Phinney, Marco Pinnoti and general Garmin Team with rides from the Dauphine.

It also clearly shows up dodgy elevation data that is in a number of segments that results in off-the-scale VAM/Relative Power values which are due to poor GPS data often causing Strava to automatically create a hill segment that actually doesn't exist! If you see segments like this you should (according to Strava) flag them and recreate them from your own ride so the elevation stats are accurate.

Worth having a look at this blog post for a bit of non-exhaustive research on quality of GPS data by device (Garmin vs phone). I've added a comment on the bottom of there with my thoughts on segments in Strava with some interesting examples. Basically, the shorter the segment, the more "Art" than "Science" the placings and timings are! Anything less than say 1 km I'd take with a pinch of salt.

 

[400bhp]

Ben-your website is excellent

Now, get on and do that percentile thingy

 

[Ben Lowe]

Now, get on and do that percentile thingy

I'm afraid that's not going to be possible I would need to get the whole leaderboard for each segment to do that and the amount of data required would kill the process completely (some segments, particularly in the US have 1000's of riders!)

I could give a percentage value of how your time compares to the KOM if that's of use? We've already got seconds behind KOM as it stands but potentially useful to have a percentage comparison as well. What do you reckon?

 

[400bhp]

Not sure what use the percentage compared to KoM would be?

For percentiles-can you get the number of riders per segment easily enough? If you can then, for every position you are in over 50 on segments where there are riders > 50, you could simply put that position as the median. E.g, say there were 2000 riders on a segment and the rider had finished outside the top 50. You could assume (for percentiles) that the rider finished in 975th place (2000 - 49)/2. The rider would therefore be assumed to be at 48%.

Alternatively you could simply assume 50% for all segments where there are >50 riders and the rider is outside the top 49.

 

[Ben Lowe]

The main issue I've got to start with is that the Strava api often returns 0 for the "total times ridden" for some reason. If you go to the Segment Explorer on their site and click on a few segments you'll see (at least I do around these parts) some saying "Times Ridden: 0" when clearly that is incorrect. That data is coming from the same api that I would need to use. Until Strava sort that out then it's a bit of a none starter for me. If they sort it then I could do something when placing <50.

Have a look at the output from their api here and look at the "num_times_all" for the 2 segment ids provided. The second returns 476 but the first returns "null" although is actually should be saying 115.

The percentage of KOM time would be something like:

Seg1: kom time - 100s; your time - 110s; behind KOM - 10s; % behind kom - 10% (or 110% of KOM time)
Seg2: kom time - 1000s; your time - 1010s; behind KOM - 10s; % behind kom - 1% (or 101% of KOM time)

Gives a more proportional view of how far behind the KOM you are. Useful?

 

[400bhp]

Yeah, could be useful actually.

 

[Andrew_P]

It also clearly shows up dodgy elevation data that is in a number of segments that results in off-the-scale VAM/Relative Power values which are due to poor GPS data often causing Strava to automatically create a hill segment that actually doesn't exist! If you see segments like this you should (according to Strava) flag them and recreate them from your own ride so the elevation stats are accurate.

Worth having a look at this blog post for a bit of non-exhaustive research on quality of GPS data by device (Garmin vs phone). I've added a comment on the bottom of there with my thoughts on segments in Strava with some interesting examples. Basically, the shorter the segment, the more "Art" than "Science" the placings and timings are! Anything less than say 1 km I'd take with a pinch of salt.

This was more or less my conclusion that a segement was only as good or bad as the users Data. Out of interest do you know if in the future it would be possible for sites like Strava to use actual OS map type data rather than users own data? I know you do not work for Stava but you see to understand the method much more than me!

 

[400bhp]

This was more or less my conclusion that a segement was only as good or bad as the users Data. Out of interest do you know if in the future it would be possible for sites like Strava to use actual OS map type data rather than users own data? I know you do not work for Stava but you see to understand the method much more than me!

Garmin do - "Elevation Correction":

Elevation Corrections cross reference the horizontal position (latitude/longitude) provided by the GPS with elevation data that has been acquired by professional surveys. When corrections to elevation data are made, each trackpoint of your activity now contains the elevation from the web service, not the elevation provided by your GPS device.
Garmin Connect selectively applies corrections to depict a more realistic representation of your elevation experience. Activities recorded from devices without a barometric altimeter are enabled with Elevation Corrections by default. Alternatively, activities recorded by devices with a barometric altimeter generally contain accurate elevation data and therefore Elevation Corrections are disabled by default. For those users who are familiar with the MotionBased Gravity service, this is the same service.

 

[Andrew_P]

Garmin do - "Elevation Correction":

I use that and since I keep forgeting so does Strava, so maybe they should make it impossible to set up a segement without elevation correction being pressed first. I cannot see how they can get round the time and distace problem though. I have been considering a little test, I have a Cadence and Speed sensor and I have thought about massively corrupting my wheel size and see how that would effect the post ride data. I would of course delete the ride lol