# Cyclemeter vs Strava--Your mileage may vary!



## beastmaster (Sep 19, 2012)

Using the exact same device (iPhone 7+) with both apps open at the same time, I am getting some fairly significant differences in over all mileage and vertical feet climbed. If my GPS signal is coming from the same device at the exact same time on the exact same trails, why would the Strava be about 14% more? Seems strange, but perhaps this is something written into the code of either Strava or Cyclemeter for some unknown reason. Anyone else notice this discrepancy between these two apps? Which one do you feel is more accurate?

Here is what happened:

Stava recorded 23.81 mi, 3981 elevation gain with a moving time of 3:42.08 while averaging 6.4mph and 1803 calories burned.

Cyclemeter recorded 22.37 mi, 3501 feet climbed with a moving time of 4:01.07 while averaging 5.57 mph and 1839 calories burned.

My stats are the same in both apps.

Seems very strange indeed.


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## huckleberry hound (Feb 27, 2015)

I've never used Cyclemeter but I know that Strava is very inaccurate. I have a Cateye bike computer that is very accurate and Strava shorts me mileage on every ride. I know that it is because the satellites have a hard time "seeing" my phone through the trees. A twenty mile ride recently Strava shorted me 2.5 miles.
I just chalk that up to the difference between using a mechanical device and GPS system that is limited in it's ability with the very tight turned trails that are under a canopy.


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## austink26 (Jun 24, 2019)

Not positive but is it possible strava calculates the distance with some algorithm that tries to match segments within the ride and if it is close enough, use those pre set values for your total? Like if you were riding parallel to a very popular 3 mile segment but you yourself did something different and did 3.25 miles, would strava assume gps issues and just assign you 3 miles and that you did the segment. 

I have definitely seen strava display incorrect ride data and segments before. I recorded with my computer and someone else had their phone with strava. We both did the same ride but when I uploaded up to strava, the maps were pretty different. Mine being what we actually did and theirs being off. 


Sent from my iPhone using Tapatalk


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## jcd46 (Jul 25, 2012)

Is anything going to be 100% accurate?

Serious question, not being a jerk.


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## adaycj (Sep 30, 2009)

i don't see a 14% variance. About 1.5 miles difference over 25 miles is pretty normal. who even knows which app is right, or if the device's hardware is the issue. it could even be a resources/sharing thing. 

Strava has a "fix mileage" feature online, so it can correct some rides. Between two devices I had a 7% difference over a few thousand miles of riding. My watch seems to short me a little, but it is far more reliable, 

turn off auto pause ... it helps,


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## edubfromktown (Sep 7, 2010)

I've used Cyclemeter since iPhone 3gs days...

Most of my friends use $trava and some have switched to Wahoo. At the end of a ride, none of our stats are the same (even among only $trava users!).

Close is good enough for me. The main reasons I log my rides are mapping routes and getting a rough calculation for miles clicked off each year.


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## Harold (Dec 23, 2003)

beastmaster said:


> Using the exact same device (iPhone 7+) with both apps open at the same time, I am getting some fairly significant differences in over all mileage and vertical feet climbed. If my GPS signal is coming from the same device at the exact same time on the exact same trails, why would the Strava be about 14% more? Seems strange, but perhaps this is something written into the code of either Strava or Cyclemeter for some unknown reason. Anyone else notice this discrepancy between these two apps? Which one do you feel is more accurate?
> 
> Here is what happened:
> 
> ...


You're going to get variance between devices and between apps. Almost nobody out there is using the 100% raw GPS data from the hardware with zero processing. And if they did, you'd see a whole lot of junk. Trust me, that processing is essential to get anything useful out of the hardware. Especially phone hardware. The differences in how the apps process that data are going to account for the differences in what they spit out for positional data.

Elevation, you might as well just stop complaining about right now. The act of measuring elevation is MUCH more challenging. Especially considering HOW that elevation is measured. On your phone, you get one of the least accurate methods available, so consequently, the apps most likely assign an elevation value from an elevation model based on the position determined by the GPS. With different results in positional data, you'll get different elevation results by default.



huckleberry hound said:


> I've never used Cyclemeter but I know that Strava is very inaccurate. I have a Cateye bike computer that is very accurate and Strava shorts me mileage on every ride. I know that it is because the satellites have a hard time "seeing" my phone through the trees. A twenty mile ride recently Strava shorted me 2.5 miles.
> I just chalk that up to the difference between using a mechanical device and GPS system that is limited in it's ability with the very tight turned trails that are under a canopy.


ANY halfway accurate GPS-only distance measurement is inaccurate and will measure short. It's not the tree cover. That has some effect, but not the effect you think. No, because GPS distance measurement is measuring a bunch of straight line segments, it will ALWAYS shortcut corners. It's never measuring the full curve. You need a wheel sensor for that.

I use a wheel sensor to measure those curves and keep a distance log regardless of whether I ride through tunnels through the mtn and lose signal, whether I am riding in the open on flat ground, or whether I'm in the woods on hillsides that affect GPS reception more than the tree cover itself. When I ride with others who have wheel sensors, our total distances are usually within a couple hundredths of a mile of each other.



austink26 said:


> Not positive but is it possible strava calculates the distance with some algorithm that tries to match segments within the ride and if it is close enough, use those pre set values for your total? Like if you were riding parallel to a very popular 3 mile segment but you yourself did something different and did 3.25 miles, would strava assume gps issues and just assign you 3 miles and that you did the segment.
> 
> I have definitely seen strava display incorrect ride data and segments before. I recorded with my computer and someone else had their phone with strava. We both did the same ride but when I uploaded up to strava, the maps were pretty different. Mine being what we actually did and theirs being off.
> 
> Sent from my iPhone using Tapatalk


No, Strava doesn't do that level of processing on the fly. The app itself is processing the raw GPS data looking for outliers, just like every other app and device does. They all have slightly different ways of doing it, but they're all doing that work. None of it looks at segments or heat map data in real time. Though you can process a GPS file with a really cool tool they have that leverages that heatmap data. But it's way too resource-intensive to run that in real time while you're riding.



jcd46 said:


> Is anything going to be 100% accurate?


Nope. Even my wheel sensor isn't 100% accurate. What it is, though, is a whole lot more consistent than GPS-only distance calculation.


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## karthur (Apr 20, 2018)

On the road my wheel speed computer and "map my ride" match up almost exactly. In thick woods and twisty trails the GPS reads almost 1 mile less per 7miles compared to the wheel speed computer.


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## huckleberry hound (Feb 27, 2015)

karthur said:


> On the road my wheel speed computer and "map my ride" match up almost exactly. In thick woods and twisty trails the GPS reads almost 1 mile less per 7miles compared to the wheel speed computer.


Same here but I guess it's because of the deficiencies of the gps as Harold pointed out.


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## Harold (Dec 23, 2003)

huckleberry hound said:


> Same here but I guess it's because of the deficiencies of the gps as Harold pointed out.


I'm not saying that trees don't affect it at all. Just that the degree to which trees affect it is less than you probably expect. Part of it is because of all the processing that devices and apps do to filter and correct the raw data as it comes in. Early GPS devices used to be completely stymied by trees and clouds. That's not as big of a deal anymore.

What's still a big deal is the terrain. And just the nature of how distances are calculated based on GPS data. It's just how it works. Being aware of that is a huge part of setting expectations about how these devices and apps work, and the information gathered from them.


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## tigris99 (Aug 26, 2012)

I have experienced 10%+ error on strava and MMR for the exact same loop, same device across multiple rides. Most of the time app was short but a couple times it said I went a but further than I did.

What I have done was road riding in basically a straight line on open ground (was a luxury not everyone has having 7+ miles of straight open ground) and with my bikes sensors going to get my bike sensors calibrated. Then I have an accurate number to tell how far off (and correct) rides in apps.

Especially right now with getting back in shape after a year off due to Injury, I'm tracking carefully so accuracy matters to me.

Sent from my SM-N975U using Tapatalk


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## beastmaster (Sep 19, 2012)

So if phone apps for measurement are off, would a Garmin be better and more accurate? I mean the type of Garmin with wheel sensors, altimeters, and barometric pressure systems as well as mapping.


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## Harold (Dec 23, 2003)

beastmaster said:


> So if phone apps for measurement are off, would a Garmin be better and more accurate? I mean the type of Garmin with wheel sensors, altimeters, and barometric pressure systems as well as mapping.


A computer with a wheel sensor will measure speed and distance more accurately. Even a $20 wired cyclocomputer. A computer with a barometric altimeter will measure elevation more accurately, but that's really only relatively speaking. To function at its best, such a sensor needs regular calibration to known elevations so you can adjust out barometric drift from changing weather conditions. This is really for spot elevation readings, too. When you're talking about constructing an elevation profile, very tiny errors in each spot measurement get compounded. Think about it, the device takes a measurement once every second or so depending on your recording interval. The longer you're out, the more likely drift from changing weather is to be an issue. I see it on my own recorded data if I stop somewhere for a bit. A half hour to an hour. The resulting elevation plot shows a jump (sometimes up, sometimes down, depends on which direction the barometric pressure is trending) once I start moving again.

With elevation, you can only get so close. You might be able to get pretty good agreement on distance between two devices with wheel sensors. On the order of hundredths of a mile for a 10-20mi ride. But the inherent difficulty in measuring elevation means that you're still likely to have several hundred to a thousand or more feet of discrepancy in the "total climbing" metric over the course of a ride of similar length.

I would even posit that you can't even know the "true" measure of your climbing total. A well calibrated wheel sensor is about as close as you're going to get for directly measuring distance. There are some variables there that will affect things...stuff like tire pressure, and any weirdness that happens as your wheel spins when you're in the air. There is no way to possibly measure total climbing over the course of a ride DIRECTLY. Every method of measurement is indirect. And further, they all make assumptions about the shape of the earth (aka, where, exactly, is 0?), which does not have a perfect shape. It's an ellipsoid. It's vaguely ellipse-shaped, but it's also lumpy, irregular, and a little bigger in the southern hemisphere. So it's best not to get too stuck on those elevation numbers. My buddies and I tend to make fish stories out of our climbing totals, and take the elevation from whoever's device recorded the most.


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## scatterbrained (Mar 11, 2008)

Personally, I'd be happy if Strava would just use the data from my GPS without screwing with it. I'd like to think my Garmin 1030 with wheel speed sensor is going to be as accurate at you're going to get on a MTB ride and yet Strava feels the need to screw with the data anyway. My speeds are always a bit slower while my segment times are always longer. Annoying.


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## Harold (Dec 23, 2003)

scatterbrained said:


> Personally, I'd be happy if Strava would just use the data from my GPS without screwing with it. I'd like to think my Garmin 1030 with wheel speed sensor is going to be as accurate at you're going to get on a MTB ride and yet Strava feels the need to screw with the data anyway. My speeds are always a bit slower while my segment times are always longer. Annoying.


Trust me, no you would not be happy if Strava used the raw, unprocessed data from your phone's GPS hardware.

Further, Strava does data quality checks on every file uploaded from another source. If there is bad data, Strava then deals with it. I have a GPS that Strava does this with, because it's constantly producing bad data. It sits in a drawer now. It really shows up odd on RideWithGPS. RWGPS doubles or triples my mileage from that device. I can't figure out what's happening, but it seems related to the bad data. Strava doesn't mess with the data from my Edge 520 (with wheel sensor), thankfully.

It might be worthwhile to run the files through a checker to see what's up.
https://www.dcrainmaker.com/tools
fit file repair tool - Home
https://www.fitfiletools.com/#/top


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## beastmaster (Sep 19, 2012)

Thank you one and all for the insights. Harold, you are fountain of information regarding all of this. A particular shoutout to you! Thanks!


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## C-H (Jan 25, 2018)

beastmaster said:


> Using the exact same device (iPhone 7+) with both apps open at the same time, I am getting some fairly significant differences in over all mileage and vertical feet climbed. If my GPS signal is coming from the same device at the exact same time on the exact same trails, why would the Strava be about 14% more? Seems strange, but perhaps this is something written into the code of either Strava or Cyclemeter for some unknown reason. Anyone else notice this discrepancy between these two apps? Which one do you feel is more accurate?
> 
> Here is what happened:
> 
> ...


They use GPS and they also probably use a different logging interval between data points. Even recording a data point every 1 second is going to give an error.
Add to that the inaccuracy of GPS in itself.
Never ever trust GPS for altitude measurements. It's not designed to handle it.

If you really need accurate data just get a sensor on the wheels. For measuring calories burned, get a power meter.


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## scatterbrained (Mar 11, 2008)

Harold said:


> Trust me, no you would not be happy if Strava used the raw, unprocessed data from your phone's GPS hardware.
> 
> Further, Strava does data quality checks on every file uploaded from another source. If there is bad data, Strava then deals with it. I have a GPS that Strava does this with, because it's constantly producing bad data. It sits in a drawer now. It really shows up odd on RideWithGPS. RWGPS doubles or triples my mileage from that device. I can't figure out what's happening, but it seems related to the bad data. Strava doesn't mess with the data from my Edge 520 (with wheel sensor), thankfully.
> 
> ...


 I didn't say "raw data", "unprocessed" or "phone". I'm talking about fairly significant differences between the results of a ride as seen on my Garmin 1030 (and in Garmin Connect) vs. what shows up on Strava. For example, my top speeds will always be several MPH slower on Strava than Garmin. I run Live Segments on Garmin, and yet the Strava times are always several (2-10) seconds slower. The Garmin gives a beep at the beginning and end of a segment so I know it's starting and stopping the clock at the right places.


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## Harold (Dec 23, 2003)

scatterbrained said:


> I didn't say "raw data", "unprocessed" or "phone". I'm talking about fairly significant differences between the results of a ride as seen on my Garmin 1030 (and in Garmin Connect) vs. what shows up on Strava. For example, my top speeds will always be several MPH slower on Strava than Garmin. I run Live Segments on Garmin, and yet the Strava times are always several (2-10) seconds slower. The Garmin gives a beep at the beginning and end of a segment so I know it's starting and stopping the clock at the right places.


You're using Live Segments as a baseline of sorts? Bad idea. Live segments are, at best, a suggestion. If you expect them to be highly precise in real time, you need to reevaluate your expectations. There's some kind of "baked in" threshold for stuff like that. Sure, the Garmin will beep, but that doesn't mean you're at the EXACT SPOT the segment starts. It just means you're close enough to it that the device is programmed to notify you.

Look, none of that changes the fact that Strava does "checks" on all data sent to them, no matter what device it comes from. While we're talking about it, it's also worth asking if you use auto pause on the device. That can also result in discrepancies between on-device data and what various websites report. That's one reason why I don't use auto pause. In addition to tripping on very slow, steep climbs, many websites recalculate stopped time vs moving time. They oftentimes do that BECAUSE auto pause sucks. This is likely to happen when the website uses a different threshold than your device. So your device continues to record, yet the website/program has a higher speed cutoff, so it says you were stopped for a longer time. This isn't screwing with your data inasmuch as it's just running different calculations based on the data you've submitted. Doubt what I'm saying? Take the same activity file and put it in a dozen different websites or programs and compare the differences between the reported total/moving/stopped time metrics.

Want something that doesn't do ANYTHING with the data you upload? Put your data into a spreadsheet.

My point in all this is to say that there are so many variables involved that it's useless to complain about these little things. There are reasons behind a LOT of the post-processing that happens behind the scenes that we as users are simply not privy to, and oftentimes it isn't useful to quibble about those details, anyway. Just being aware of it and setting reasonable expectations is all that needs to happen.


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