Knowledge Base/Strava Knowledge Base/Strava Segments

Optimizing Segment Creation: how to create good segments

Rosie
posted this on February 27, 2012 03:57 PM

There are certain rules to follow when creating segments that can minimize the amount of problems your segment will experience.

It is possible to decrease the risk of producing false-positives, missing, and inaccurate matches, and more.  For detailed information about how to optimize your segment creation, please see the information below detailing the types of segments to avoid, and the specific problems to which those segments can be vulnerable.

 

In this article:

Tips to get started:

Zoom in!  The closer you can see the data that you're working with, the better the end result will be.  Switch away from Terrain Maps (at the top right of your map display) to either Standard or Satellite maps to enable you to zoom in further.  Keep in mind that when you're at the segment creation page, the "Move Start/End Point" buttons are dynamic; when you are zoomed out, they will move the endpoints of your segment in large increments - as you zoom in, they will make finer adjustments. 

Very short Segments

Segments that are very short - for example, sprints that take less than 15 seconds to complete - will be much more prone to matching errors than longer segments.  There are two severely limiting factors for segments like this.

First is the sampling rate of your GPS device; some devices only record a GPS point every 5 to 10 seconds - meaning that the margin of error of your segment match accounts for a very high percentage of the total segment time, since the segment is so short.  In the example below, you can see that there is no GPS point that falls exactly on the start and end points for the segment, and that the entire segment match is comprised of only four GPS points

Strava_Segment___Last_push.jpg Strava___Explore___Visualize-4-2.jpg

Furthermore, since the segment is so short - in terms of distance this time - the start and end points will be very close together.  There is a degree of leniency necessary in our segment matching system to account for inaccuracies in GPS data, and it's possible that both the start and end points of a very short segment can fall within the 'buffer' zone intended to allow for slight GPS drift.  This can cause our system to match the segment when there is hardly any overlap between the segment and the ride.

Strava_Segment___Buildings_to_Play_Structure.jpg Strava___Explore___Visualize-3-1.jpg

 

Segments with bad start or end points

Segments created with start points in less than ideal positions can also be very problematic.  For example, if you create your segment in such a way that it starts too early, some users may have trouble matching that segment; see below left for an illustrated example of this.

Strava_Segment___bad_start_point_example-1.jpg Strava_Segment___KOA_to_Hualalai.jpg

Additionally, placing your segment start point too close to an intersection might lead to inaccurate segment times.  The reason for this is that if there is a stop sign or other traffic regulation for the intersection at which the segment starts, users might trigger the start of their segment match prior to stopping - meaning that their time while stopped at the intersection will be included in their time for the segment. See above right for an example of this.

The reverse of both of these examples is also true; placing the end point of your segment too close to an intersection can lead to stopped time being included in a segment effort.  This is very common at the top of climbs; when a segment finishes too close to an intersection, users will often stop to rest after pushing themselves up the climb - causing their resting time to be counted into their segment time.  Likewise, placing your segment start point after an intersection can cause some users not to match at all, if they don't turn the same direction that the segment does.

 

Tight Switchbacks

Segments that start or end on a tight switchback turn can cause bad matches.  Because our system allows for some small margin of error to account for GPS drift, it is possible that you can trigger the start or end of a segment before or after you actually should have - if the road or trail makes a very tight turn and turns away from, then returns close to the true endpoint.  We are hard at work on improving this situation, and hope to handle these segments better in the future.  In the meantime, the best way to increase your chances of a good match to segments like the one shown below is to extend the segment as far from its own 'tail' as possible (while conforming to the other guidelines discussed on this page).

Strava___Explore___Visualize-5-1.jpg

 

Trails that parallel roads

Because our system allows for some small margin of error to account for GPS drift, if a trail segment runs parallel to a road segment and the two are close enough together, it may not be possible for Strava to provide mutually exclusive results.  This means that athletes riding or running on the road may match (and receive unrealistic times) on the trail segment, and vice versa.  Unfortunately if the two paths are close enough together for this to be an issue, the only way to improve your chances for accurate matches is to move the segment endpoints further away.

Strava___Explore___Visualize-6.jpg

 

Very long segments

Longer segments are generally more accurate than shorter ones - however only to a certain extent.  If you are completing a 30-mile long segment but make even a very small deviation from the route that the segment follows, you won't be able to match the segment.  Even though a one-block discrepancy might have little effect on your time for the segment, any deviation from the segment's route will prevent it from matching your activity.  See below for an example of this.

Strava___Explore___Visualize-7.jpg Strava_-_Explore_-_Visualize-1_2.jpg

 

Very complex segments

Certain segments are just so complex - composed of so many tight twists and turns - that we are unable to give completely accurate results.  This is sometimes evident on cyclocross courses, tightly-packed trail networks, etc.  This is exacerbated by the fact that segments like this are most often found off-road - with tree cover frequently negatively affecting the quality of both the segment and the activity GPS signal.  Once again, there unfortunately isn't a real solution to this problem other than to use the best available GPS data, and whenever possible follow the other guidelines described here.

Strava_Segment___CCCX_1_Lap.jpg

 

Tunnels

Any time your route takes you through a tunnel of any significant length - as are common in mountainous areas - your GPS signal will be lost, and it is very likely that the distance you travel while without a GPS signal will be long enough to trigger our 'Gap Threshold.'  This means that segments that incorporate tunnels will be unlikely to produce accurate matches to your activities.  Unfortunately there isn't a great workaround for this - the best solution is to simply avoid creating segments that include tunnels longer than around 500 meters.

Strava_Segment___Puerto_Ventana__desde_Teverga_.jpg

 

Things to keep in mind 

Use good quality data!

Quality GPS data is key to accurate segment recognition.  Since we use the GPS data from your activity to create segments, it's crucial that segments are created from activities with high quality GPS data - and that, whenever possible, are recorded on a high quality GPS device.  Not all GPS devices are created equal but even for the most accurate devices, trees, tall buildings, and even clouds can wreak havoc on GPS signal.  Look closely at your activity before choosing it as the basis from which you create your segment; if the GPS data looks jumpy or doesn't follow your route closely, try using another activity.

Timing Issues

Recording intervals vary between devices - for example, the Strava mobile app records every second while Garmin devices use either 1-second intervals or a smart recording which has a varied recording interval. Segment matching works the same on each GPS dataset, but depending on the device's recording interval, can yield different results. Segment matching uses the GPS points in the data closest to the start and endpoints of the segment, and as this can vary with each activity, timing on a segment can vary slightly because of this. At the present time, we don't interpolate or extrapolate GPS data to normalize for the exact start and end positions of the segment. 

Are there duplicates?

Check to see if the segment already exists. After you specify a start and end point and click "Next," you may see a list of similar segments. Review them to see if the new segment you're proposing is truly new. Sometimes the segment exists, but poor quality location data prevents Strava from matching them. In these cases, see Segment Matching Issues for instructions on what to do.  Keep in mind that if there is a segment found that is similar to the one you're creating, selecting to "Use" that segment won't automatically add it to your activity.

For more information on Creating Segments, see here.

Re-Routed off-road trails

If you are attempting to create a segment to account for an off-road trail that has been re-routed in response to environmental changes, there unfortunately isn't a way to prevent users on the old 'version' of the trail from matching the new one - or vice versa - assuming the two trails are similar enough to match regardless of which route was followed.  The best option is to filter segment results by 'This Month,' 'This Year,' etc.

 

Comments

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Mat Gordon
Strava Support

Questions or feedback about this article? I'm interested in making sure these are as helpful and informative as possible - so if you have any thoughts please feel free to comment.

Keep in mind, however, that this not the best place to request support - for that please create a support ticket.

November 05, 2013 05:15 PM
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Duncan Styles

is there a way to see the mapped segment and compare to the gps locations recorded for a ride?  Thus we can see where the ride deviated from the segment and "correct" the ride so the segment is recorded each time?  thanks,  Duncan

November 23, 2013 11:13 AM
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Mat Gordon
Strava Support

Unfortunately there isn't currently a user-facing tool for this - although this is something we've talked about and hope to make possible in the future.  If there's a specific activity/segment pair you're looking at, you can create a support ticket with those links and we can send you a screenshot.

 

Thanks!

November 25, 2013 09:15 AM
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Benjamin C.

Where I live, there is a beach that I like to run along. The problem we have is when you run down the beach, if you are ever so slightly to the left or the right of the segment, Strava never detects you ran the segment. I've have ran this annoying beach so many times now, in search of the segments, that I'm now fitter and faster than ever before.  But the segments still remain elusive, it's proving impossible to find the right line. 

December 01, 2013 11:01 AM
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Mat Gordon
Strava Support

Benjamin - 

It sounds like perhaps the segment you're describing was created with some bad GPS data.  The best solution might be to create your own segment based on your run - hopefully that will match more consistently.

December 02, 2013 09:31 AM
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Duncan Styles

I got caught out recently with a segment I had created, and used several times was not getting adding to my activities .   The solution was to start the segment outside my privacy zone, or in my case to delete the privacy zone.  You can probably move the privacy zone away from the segment so it starts outside, but your house remains inside the zone....

December 02, 2013 04:41 PM
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Richard Serton

Is there currently a way to separate out segment results based on a specific date?  Here's what I mean - let's say the same course is used for a cyclocross race in multiple years.  What I would like to do is create a segment which is a lap of the course and only allow riders to compete for the KOM if they completed it on a specific date.  This way, we can see who rode the course fastest based on the same conditions.  Lap times vary hugely from year to year depending on course conditions.  Similar situations occur in time trial courses which are used over and over.  One year, there could be a strong head/tailwind, the next year it could be calm.   Thanks!

December 03, 2013 11:07 AM
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Mat Gordon
Strava Support

Richard - At this point you can filter segment results (from the segment leaderboard page) by results from "Today," "This week," "This Month," and "This Year," - that's unfortunately it at this point.

 

December 03, 2013 11:39 AM
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Christian H.

Strava Newby here - How does Strava cope with laps. So if there is a segment which is a loop done twice, can Strava tell that the first time crossing the start/finish line isn't the end of the segment, and should wait for the second crossing? i.e. does it match the distance as well as the GPS position to trigger the end of the segment?

December 04, 2013 08:17 AM
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Mat Gordon
Strava Support

Christian - 

Yes - multi-lap segments actually should work just fine.  

December 04, 2013 08:49 AM
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Marcio Telles

multi-lap segment is fine, but how does strava deal with the following?

For example:

I created a segment with 10 laps, that i use to make a time trial training.

if i warm up for 4 laps, strava is considering these 4 laps as part of the 10!!

Would it be possible for strava to consider EVERY 10 consecutive laps?

Than i can get the fastest 10 laps of my training.

December 17, 2013 01:17 PM
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Luciano Resende

I find Richard Serton's very interesting too. There are several segments on my area that were used on a race. However, despite all the training on dry conditions the race day was under heavy rain, so, all the timing, KOMs, etc does not reflect that day race. At that week it was possible to use the filter, but now, I`m not able to see all times from a specific date.

December 28, 2013 11:32 AM
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Dan Aponik

I'd like to do my part to help name segments on the roads I use commonly.  Is there a way for me to rename segments that I find on my routes that are called "Not yet named"?

January 11, 2014 08:43 PM
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Arcellus Sykes

Possibly a silly question but - should one create segments in both directions of an out-and-back? 

January 15, 2014 01:40 PM
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Laurent Arditi
When comparing segment times, the resting time is taken into account. This is bad when for example waiting for a green light, or for a friend. Should have a switch to compare times with or without resting times.
January 19, 2014 08:58 AM
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Laurent Arditi
Segments do not seem to work for hiking activities. Is that normal?
Thanks!
January 19, 2014 08:59 AM
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Richard Banks

Is it possible to create a segment that allows for people to run multiple routes to get there?  I live in a city with lots of bridges, and it would be mildly interesting to compare the different options to go from bridge to bridge via a segment.  e.g. I hand created this segment by editing a GPX, and uploaded it but it didn't match any other runs.  I suspect due to the distance being shorter than other runs

http://app.strava.com/segments/6540540?filter=overall

 

January 27, 2014 04:58 PM
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Mat Gordon
Strava Support

Richard - Unfortunately not - it's not possible to create a segment that will allow multiple routes.

Laurent - this is by design; segments are like little races; so they are based on elapsed time, not moving time.

Arcellus - This depends on what you want!  Segments will only match activities that go the same direction as the segment.

Dan - There isn't a way for you to do this; but if you send these segments to Support, we can do it for you.

Luciano - Unfortunately there isn't a way to 'restrict' a segment to only matching activities from a certain date range.

Marcio - if you create a ten-lap segment, and then ride - say - twelve laps; you should get three matches to that segment - one for laps 1-10; 2-11; and 3-12.  However, please also be understanding that the more complex your segment is... The more trouble we're going to have identifying accurate - and ONLY accurate matches.

 

Finally - I've left this page open for comments in order to get feedback about the article itself and how it can be more helpful; if you have specific questions about your own segments, etc. - please create a support ticket.


Thanks!

January 28, 2014 11:32 AM
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Mark Hardy

Mat

Regarding your 10 lap answer; people have set up 2, 3 and 4 lap segments around our local MTB riding trail. I have noticed that if I do 3 laps I only get the 2 lap segment ONCE, on laps 1 and 2. If I do 4 laps, I get the 2 lap segment twice - on laps 1 and 2 and also on laps 3 and 4. I suspect Strava does NOT allow the same segment to be tracked multiple times simultaneously. SO, while I am on lap 2, I am riding the 2 lap segment for the first time, this prevents Strava from registering the same segment on lap 2 and 3 because they are happening simultaneously. This is at odds with the answer you gave Marcio concerning 10 laps. But having ridden my local trails to death I can vouch that I have never seen multi lap segments being detected on adjacent laps as you described to Marcio.

 

Mark

February 11, 2014 05:26 PM
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P P

My question has not to do with segment creation, but real-time segments. Sorry if this is the wrong place to post. Strava offers a premium feature that enables to compare segments in real time with the community.

 

What I am interested in is to compare with myself. I usually run the same course, and would like to compare my segments in real time to my past performance. I would like to have audio announcements like: "Segment completed in 6:01, 4th personal best. Best ever personal segment time: 5:49"

 

And I would like to have that in the free version please! I am starting to move away from Runkeeper and SmartRunner. A better real-time segment management in the free version would definitely make me turn to Srava for good.

I am not interested to compare my segments to the community in real time, I can check that later online.

 

February 17, 2014 12:08 AM
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Panos Siman

How can I create a segment for my way back? I can't find a way. I want the segment to be the climb on my way back not the downhill that is when I start the workout.

February 19, 2014 01:50 AM
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Panos Siman

Found it. Me bad.

February 19, 2014 02:07 AM
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Mat Gordon
Strava Support

Hello all - 

My intent for leaving this page open for comments was to gather feedback about the article itself, and how I might be able to make it more useful and informative.  The best way for you to get rapid and personal support is still to create a support ticket - so in light of that I'm going to close this thread for comments.  If you have any questions, please feel free to create a support ticket - and thanks for understanding.

-Mat

Strava Support

February 25, 2014 10:53 AM
Topic is closed for comments