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Did an "iPhone vs Garmin 500" ride today…interesting results.

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Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

Did an "iPhone vs Garmin 500" ride today…interesting results.

Old 12-01-13, 03:12 PM
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Smokehouse
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Did an "iPhone vs Garmin 500" ride today…interesting results.

Finally picked up a Garmin 500 and decided to run both it and Strava on an iPhone 4s…the results were interesting. I'll be listing the results a iPhone first - 500 second.

Distance: 32.0mi - 31.5mi
Elevation: 489ft - 794ft
Moving time (both ran the entire time): 2:07:12 - 2:03:02
Calories: 1052 - 852
Max speed: 40.5 mph (WTF?) - 23.7 mph
Ave speed: 15.1 mph - 15.4 mph
Ave PWR (Strava est): 124w - 106w

I'm not too surprised at the quirky top speed stuff…as I've had that happen to me before. I'm more surprised on the elevation accuracy, that's a BIG difference. Figuring I've used the iPhone all season and have 22,000+ ft of climbing registered, I'm curious what my real numbers are.

I guess I'll find out next summer!

I found this info to be interesting, I figured many of you would too...
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Old 12-01-13, 03:17 PM
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Elevation readings are always going to vary from one device to another as there is no standard way to define elevation gain. If they just take the raw GPS elevation readings the elevation gain will naturally be higher as there is a fair amount of noise in the signal that gets counted as elevation change. The Garmin 500 uses a barometric altimeter so it should be more accurate than the iphone.
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Old 12-01-13, 03:17 PM
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Don't trust the Garmin for elevation. It's known to be bad. Your phone is probably using the elevation data for the area you're riding.

Everything else I'd trust the Garmin over an app on your phone. Even more so if you put the GSC-10 sensor on your bike.
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Old 12-01-13, 03:19 PM
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Originally Posted by gregf83 View Post
The Garmin 500 uses a barometric altimeter so it should be more accurate than the iphone.
The Garmin's barometer is drastically affected by temperature. I often gain 100 ft of altitude while riding on the trainer in my basement.
I'd trust something that uses known elevation data and maps it over your GPS track.
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Old 12-01-13, 03:25 PM
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Originally Posted by ancker View Post
The Garmin's barometer is drastically affected by temperature. I often gain 100 ft of altitude while riding on the trainer in my basement.
I'd trust something that uses known elevation data and maps it over your GPS track.
100 ft of elevation change in an hour is small compared to the error you can accumulate with a GPS receiver. The issue isn't the absolute accuracy it's the small changes that between each reading (i.e. noise). It's like trying to measure the length of the coastline. The finer the measurement the longer the coastline appears.

If you want to use elevation data you can correct the Garmin data as well but the elevation data isn't always accurate either.
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Old 12-01-13, 03:53 PM
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I agree with gregf. Elevation by GPS can be pretty wildly inaccurate - if you examine a GPS track and see how your ride can be traced +/- 10-20ft of your actual position in 2 dimensions at any given time. Most software takes your GPS track and then overlays that on a topo-map to determine elevation gain.
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Old 12-01-13, 04:07 PM
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Originally Posted by ancker View Post
Don't trust the Garmin for elevation. It's known to be bad. Your phone is probably using the elevation data for the area you're riding.

Everything else I'd trust the Garmin over an app on your phone. Even more so if you put the GSC-10 sensor on your bike.
Yeah…I read that when I was looking up the 500 before I picked one up. I landed up getting the speed/CAD and heart sensors as well. I really use the CAD sensor quite a bit, it's helped me "spin" more rather than chug things out like I've done in the past. I like the fact that I can log trainer sessions as well.

Originally Posted by Beaker View Post
I agree with gregf. Elevation by GPS can be pretty wildly inaccurate - if you examine a GPS track and see how your ride can be traced +/- 10-20ft of your actual position in 2 dimensions at any given time. Most software takes your GPS track and then overlays that on a topo-map to determine elevation gain.
I've seen the Strava ap do this. When I first finished today and ended the Strava ap on my phone, it said 1000+ feet of elevation change Once it sync'd, that # dropped to under 500'.

*EDIT*
Mapped my ride out on Ride With GPS and they listed it as +680'…so 200 more than the iPhone but 100 less than the 500. Hmmm...

Last edited by Smokehouse; 12-01-13 at 04:12 PM.
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Old 12-01-13, 04:35 PM
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Originally Posted by Smokehouse View Post
Mapped my ride out on Ride With GPS and they listed it as +680'…so 200 more than the iPhone but 100 less than the 500. Hmmm...
From RidewithGPS: Why does my planned route have a different gain loss than I expect?
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Old 12-01-13, 04:54 PM
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Originally Posted by gregf83 View Post
...well crap, LOL...guess there's really no way to tell 100% then huh? The 500 data is closer to RWGPS so I'll go with that one.
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Old 12-01-13, 09:19 PM
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I'm a newbie but ridden quite a bit of Strava and compared Iphone to Garmin and Android. They all have their drawbacks, but the Garmin mid to higher end units are the most accurate. Strava app on Iphone and Android usually does a poor job of calculating stopping time, since they require a 15-20 second motionless minimum. So a lot of stopping time is actually added to the ride time giving you a higher moving time plus a lower average speed. Top speed is usually overestimated with iphone but segment times are usually within a second or two (either to your advantage or detriment) of a garmin unit. If you really want to use your iphone, you may want to use something like motionx gps and record your ride and then upload the gpx file to strava. I get better tracking this way.
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Old 12-01-13, 09:45 PM
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I'm looking at getting a RFLKT+ and an ANT speed and cadence sensor specifically to get more accurate speed/pace numbers on my iPhone for my rides. My chief complaint is the way apps calculate an average speed via GPS position.

Currently running the MotionX GPS app, but I'm looking into the Strava app (or something like it) if I can figure out how to lock down the profiles so my ride data isn't shared Facebook-style with the world.
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Old 12-01-13, 09:50 PM
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Originally Posted by john.b View Post
I'm looking at getting a RFLKT+ and an ANT speed and cadence sensor specifically to get more accurate speed/pace numbers on my iPhone for my rides. My chief complaint is the way apps calculate an average speed via GPS position.

Currently running the MotionX GPS app, but I'm looking into the Strava app (or something like it) if I can figure out how to lock down the profiles so my ride data isn't shared Facebook-style with the world.
You just tell it not to, I believe you can make each session private if you want. Not sure how that effects king of the hill segments but I know it will keep others from seeing your rides.
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Old 12-01-13, 10:05 PM
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You can certainly make each ride you do private, but you will not get credit for any KOMs and other achievements. You would have to do this for every ride. There is no default "make all rides private" feature. You can also select enhanced privacy on your profile so only strava users or followers you approve can see your rides. This way your achievements/KOMs will be listed but only strava members you approve can see your ride detail.
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Old 12-02-13, 03:17 AM
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That is why I stopped using GPS for my cycling data. Now I use wheel magnet cyclocomp and everything is just fine. No more ridiculous max speeds and averages.
No, I don't get altitude, but GPS is so inaccurate is mostly useless anyway. And looking at my route on the map gets old after some time.
Sometimes I take my Suunto with me (barometric measurement with calibration at known points) and that's it.
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Old 12-02-13, 07:32 AM
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My Edge 500 is quite a bit off of my Android. I got the cadence/speed sensor and that helped a BUNCH. Not really sure how acurate the 500 GPS tracking is. Before getting the edge my cycle computer and Strava were always equal on time, distance, average and top speed. I was shocked to find out that a $250.00 computer was no where close to the accuracy of a $50.00 computer.

After adding the sensor Garmin Connect and Endomondo are spot on but Strava is still off a bit. If I was one to compete for KOM's I'd be a bit upset with the Garmin as it's always slower on Strava. Oh well, I'm just lucky to be able to get out and ride.
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Old 12-02-13, 08:36 AM
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Were you using a speed/cadence sensor and HRM with the Garmin, or were you just using the gps tracking?

Also, when you loaded the ride into garmin connect, do you have elevation correction enabled or not?

For the moving time, does garmin pause when you come to a complete stop or ride under a certain mph?
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Old 12-02-13, 09:12 AM
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As I stated in my post, I started using the Garmin withough the speed/cadence sensor...it was way off. WIth the sensor it is closer but my problem is with the way Strava and Garmin talk to each other. Garmin connect and Endomondo are always spot on. With my phone Strava and Endomondo are spot on. With my Garmin, Strava is not reading the data properly.

I don't worry about elevation. It's pretty flat here in Nebraska. We don't have any "real" climes of any length. I have one 12% grade that I take once in a great while and it lasts just over a quarter mile. 3-4% are the norm with 6% every now and then. Again, no real distance involved either.

The Garmin is set to pause under 3mph.

Originally Posted by SpeshulEd View Post
Were you using a speed/cadence sensor and HRM with the Garmin, or were you just using the gps tracking?

Also, when you loaded the ride into garmin connect, do you have elevation correction enabled or not?

For the moving time, does garmin pause when you come to a complete stop or ride under a certain mph?
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Old 12-02-13, 10:12 AM
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Originally Posted by SpeshulEd View Post
Were you using a speed/cadence sensor and HRM with the Garmin, or were you just using the gps tracking?

Also, when you loaded the ride into garmin connect, do you have elevation correction enabled or not?

For the moving time, does garmin pause when you come to a complete stop or ride under a certain mph?
Me?

Yes, I was using the speed/CAD sensor as well as the HR monitor. I uploaded my data to Strava, haven't used Gamin Connect yet. As for the stopping, due to using the CAD/speed sensor, it auto pauses when my wheel stops moving...so a complete stop will do it. It's funny though, pausing the Strava ap will 100% pause your ride. I've used this feature for mid ride breaks that will last 15 or so min. The Garmin, although it shows it being paused, will register it as a "zero movement" period on Strava.
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Old 12-02-13, 10:32 AM
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Barometric altimeters in Garmins aren't perfect either. The problem is that they need a clean monitor port. They can get interference from high winds or high speed descents.
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Old 12-02-13, 12:02 PM
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Originally Posted by gregf83 View Post
there is no standard way to define elevation gain.
That's crazy talk.
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Old 12-02-13, 12:13 PM
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I used a rollout-calibrated Cateye for a while until I realized that my Android phone running Strava was only off by about 0.1 miles every 25 miles. I took the computer off of my bike. I've never had an issue with max speed and get reasonable results when compared to riding buddies with computers. Elevation seems to vary widely depending on the measurement method, it's probably the least reliable metric for any device.
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Old 12-02-13, 12:25 PM
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I think the iPhone takes it's elevation from something like Google maps etc. The reason I say this is that I live in south Florida and on my weekend ride I have one "climb" of about 75 feet over a drawbridge and Strava shows 0 feet of climbing. I assume that Google maps or whatever the source is is thinking the road goes straight and level across the Intercoastal. I have a GPS compass app on my phone and I have stopped and taken a reading and it shows my elevation at 73 feet.
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Old 12-02-13, 07:50 PM
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Originally Posted by 99Klein View Post
As I stated in my post, I started using the Garmin withough the speed/cadence sensor...it was way off. WIth the sensor it is closer but my problem is with the way Strava and Garmin talk to each other. Garmin connect and Endomondo are always spot on. With my phone Strava and Endomondo are spot on. With my Garmin, Strava is not reading the data properly.

I don't worry about elevation. It's pretty flat here in Nebraska. We don't have any "real" climes of any length. I have one 12% grade that I take once in a great while and it lasts just over a quarter mile. 3-4% are the norm with 6% every now and then. Again, no real distance involved either.

The Garmin is set to pause under 3mph.
Originally Posted by Smokehouse View Post
Me?

Yes, I was using the speed/CAD sensor as well as the HR monitor. I uploaded my data to Strava, haven't used Gamin Connect yet. As for the stopping, due to using the CAD/speed sensor, it auto pauses when my wheel stops moving...so a complete stop will do it. It's funny though, pausing the Strava ap will 100% pause your ride. I've used this feature for mid ride breaks that will last 15 or so min. The Garmin, although it shows it being paused, will register it as a "zero movement" period on Strava.
Sorry, I was referring to Smokehouse. Still it sounds like both of you are having similar issues.

If you're using a speed/cadence sensor with the garmin and just gps with strava, I'd imagine that would be why the times and distances are off. If you're using the HRM, you're probably getting more accurate calories on the garmin as well. Since Strava is just guessing based on speed/age/body type/etc - however, both are probably still higher than what you're actually burning.

I'd try setting up a garmin connect account if you don't have one already, and then upload the file to garmin connect. My garmin connect always matches my garmin 100%. After that I export the TCX file and upload that to Strava - I've noticed it shorts my speed by about .4mph at times and my calories are always a mess. It also likes to add elevation, sometimes I've had it add over 1000' on century rides where I rode with others, using the "enable elevation correction" option usually fixes this.

I'd imagine the two should be off, but not that off.

Blah, I'm rambling and keep getting interrupted, pay no mind to me as none of this probably makes any sense.

On a side note, this website is really handy at uploading your garmin connect items to strava automatically - they used to be almost instantaneous, but had some issues a few months back and now it takes between 10min-couple of hours. Still handy if you don't have time to upload files everywhere.
https://www.copymysports.com/
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Old 12-26-13, 03:47 PM
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I used strava for almost a year and always got frustrated with the weird speeds and elevations (60 mph max speed?!) and finally just got rid of it and started riding without any computers. As liberating as that was, i wanted to know some data so i got a cateye. Now, i get accurate distance, time, speed and HR. Oddly, i'm finding myself missing elevation gain. I'm thinking now that i have a new iphone with LTE coverage, would that affect the elevation matter at all?
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Old 12-30-13, 11:08 AM
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Originally Posted by Mayday.JP View Post
I used strava for almost a year and always got frustrated with the weird speeds and elevations (60 mph max speed?!) and finally just got rid of it and started riding without any computers. As liberating as that was, i wanted to know some data so i got a cateye. Now, i get accurate distance, time, speed and HR. Oddly, i'm finding myself missing elevation gain. I'm thinking now that i have a new iphone with LTE coverage, would that affect the elevation matter at all?
I don't think so...

I had an iPhone 4s (company phone), ran Stava on it...then got a iPhone 5 LTE (personal) ran strava and they elevations/speeds/whatever were the same...went BACK to an iPhone 4s (company phone again), ran Strava...noticed no difference.

The crazy stat crap drove me nuts too. I finally had enough when myself and another rider did 75 some miles and my phone registered one elevation amount, and his Garmin was considerably higher. I don't look for "KOM" crap for some off verification that I am a cyclist...but I love the yearbook feature of miles and elevation climbed. This is why I got the Garmin. These rides are my "legacy"...these stats I will look at one day when I possibly cannot ride anymore...this is the history of my accomplishments. I want to make sure stuff is logged correctly.
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