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  1. #1
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    Garmin Edge 500 accuracy?

    I've been using a cheap cyclemeter (that I can't see anyway at 5:30AM except for the split second that I pass under a street light) and an iphone in my jersey pocket running an app- either Strava or Map My Ride - just to see the data afterwards. The accuracy of the apps, or my phone gps, is way off. I can do the same route over and over and never get the same distance twice. It told me my max speed a couple of days ago was 39mph on a ride that I am quite sure I never even hit 30.

    I'm planning on getting a Garmin Edge 500 soon. I'm already sold on it for lots of the features, including the hrm & cadence. I don't really consider it crucial that I know the exact speed and distance, but should I expect that data to be any more accurate on the Garmin than an iphone app?

  2. #2
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    The iphone isn't true GPS, it is assisted so it can be off a bit. The Edge is a dedicated GPS also with wheel mag.

    I love my Edge. It sometimes is a bit quirky with hill grade but with a quick shake it usually corrects itself(I frequently start with 695% grade). It has an accuracy screen(mine usually shows within 11 feet.

  3. #3
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    I just picked up an Edge 500 this week. Absolutely love it! Easy to import data into Garmin Connect or Strava.

  4. #4
    Re-Cyclist
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    Edge is great. No wheel magnet or wires needed. Easy to switch to any bike I ride. Fairly accurate, certainly enough for a bike ride.

    I do the same ride often and the distance is always within .2 miles.
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  5. #5
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    you can increase accuracy with the cadence/wheel sensor.

  6. #6
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    Accuracy

    The overall accuracy of the Edge is IME very good, but the instantaneous number on the screen is only so-so without a separate speed sensor.

    Just use an ANT+ Powertap to give you speed data... among other things?

  7. #7
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    If the hrm is an important feature for you then you may want to read other sites besides here. Seems like it's a hit or miss and dependent on the clothing you wear. He does have the mod the guys in Australia came up with that apparently helps the hrm work correctly.

  8. #8
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    Quote Originally Posted by EastonZ16 View Post
    The iphone isn't true GPS, it is assisted so it can be off a bit.
    Huh???
    All the GPS devices record at intervals, and some have higher sensitivity receivers. The max speed gets off because it might have lost the signal temporarily between those intervals. As to the overall accuracy, if you look at the average speed and distance, it's very close. You should be off by less than 1/10th of a mile on a 30 mile ride.
    As mentioned above, a speed sensor will make it a lot better. Yes, the garmin reeivers will be more sensitive than an iphone one.
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  9. #9
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    Quote Originally Posted by Peanya View Post
    Huh???
    All the GPS devices record at intervals, and some have higher sensitivity receivers. The max speed gets off because it might have lost the signal temporarily between those intervals. As to the overall accuracy, if you look at the average speed and distance, it's very close. You should be off by less than 1/10th of a mile on a 30 mile ride.
    As mentioned above, a speed sensor will make it a lot better. Yes, the garmin reeivers will be more sensitive than an iphone one.
    The iPhone does not have satelite capabilities, unlike the Edge, therefore it is not a true GPS. I am not saying it is extremely different but it can give odd readings at times, just like when you open the map app on the highway and it has you driving in the field next to the highway.

  10. #10
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    Quote Originally Posted by EastonZ16 View Post
    The iPhone does not have satelite capabilities, unlike the Edge, therefore it is not a true GPS. .
    Yes it does. It receives gps satellite signals just like all other gps devices.

  11. #11
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    Quote Originally Posted by EastonZ16 View Post
    The iPhone does not have satelite capabilities, unlike the Edge, therefore it is not a true GPS. I am not saying it is extremely different but it can give odd readings at times, just like when you open the map app on the highway and it has you driving in the field next to the highway.
    You're incorrect. When you open the app, the phone uses signals off of towers to triangulate a rough location, so it can start loading up the correct maps. As you notice on a Garmin (and phones too), acquiring a GPS signal takes some time, and the more sensitive the receiver, the faster. Now, if you're talking about the first generation (pre 3G) iphone, then your statement would be correct. They did not have GPS receivers in those.
    Oh, all modern cell phones are required to have a GPS receiver in them, because of 911 phone calls.
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  12. #12
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    Direct from Apples website

    Assisted GPS and GLONASS
    Digital compass
    Wi-Fi
    Cellular

    I dont want to get into an arguement but all I said was the Edge is a better GPS because it uses direct to satelite info. The iPhone is assisted and can be a little off at times...

  13. #13
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    I guess you didn't read what the "assisted" part is that I posted, or you're just trying to bash Apple products. There's a LOT of stuff you can bash them on, but not their GPS. Let's take the way they block Android apps from being fully featured as the apple ones. Or that you'll never have flash. Or that you can't upload music from your phone to your computer. Or that you can't use apps unless they're approved by the almighty Apple....
    The assisting part is to help it find a closer spot when the GPS signal isn't acquired or if it's lost. When it's got a lock, it's every bit the same signal that a Garmin uses.
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  14. #14
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    Quote Originally Posted by Peanya View Post
    Oh, all modern cell phones are required to have a GPS receiver in them, because of 911 phone calls.
    Hi,

    All modern cell phones are not required to have GPS (a specific satellite system), many simply use cell tower data to triangulate position roughly. I am not commenting directly on the iPhone, just cell phones in general.

  15. #15
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    Iphone does use satellites, both US and the GLONASS (the "Soviet" GPS array).

    Back the late 90s surveyor grade instruments using the GLONASS array were all the rage because the US system was still using a built in error factor, thus the GLONASS system provided a more accurate postion.

  16. #16
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    Can anyone comment on the accuracy of the Garmin 500?

  17. #17
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    Quote Originally Posted by rgordin View Post
    Can anyone comment on the accuracy of the Garmin 500?
    Yes. It is sufficiently accurate, especially when using a wheel sensor, which helps compensates for GPS position noise and straight-lining between fixes.

    I'll also mention that several smartphones I use have excellent GPS position accuracy in areas far outside of cell coverage.

  18. #18
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    I had one but returned it after a couple of days later.

    The deal breaker for me was the heart rate monitor not working properly. After a few hours of trying, it finally registered my heart rate but that was after getting my Polar WearLink strap (not transmitter, just the strap). Even then it would drop out when moving around normally (walking around the house, not on a bike).

    Now I am using a Polar RS800CX watch with the G5 GPS, speed and cadence sensors with universal bike mount. It doesn't have all the fancy features like 3 pages of information that rotates but the HRM does work without any issues.

  19. #19
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    Quote Originally Posted by Peanya View Post
    I guess you didn't read what the "assisted" part is that I posted, or you're just trying to bash Apple products. There's a LOT of stuff you can bash them on, but not their GPS. Let's take the way they block Android apps from being fully featured as the apple ones. Or that you'll never have flash. Or that you can't upload music from your phone to your computer. Or that you can't use apps unless they're approved by the almighty Apple....
    The assisting part is to help it find a closer spot when the GPS signal isn't acquired or if it's lost. When it's got a lock, it's every bit the same signal that a Garmin uses.
    I'm not even sure that's what they mean by 'assisted.' I believe they mean that while the phone itself does have the GPS circuitry, the maps themselves are 'in the cloud,' rather than being stored locally.

    With the right app, you can record GPS tracks in with the cell signal disabled.

    All said, the dedicated GPS device will still be more consistently accurate.
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  20. #20
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    Using Strava iPhone app my top speed is 58mph! Using my Garmin 705 on the same exact place it's 35.5 I think I might stick with my iPhone! Lol on both the total ride distance is within 1/10 and avg speed is usually the same. I bought the Garmin for cadence and hr. it all depends on what you want to track.

  21. #21
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    I have no problem with the accuracy of the Edge 500. Same rides will read within a few 1/100's of a mile difference. HRM works fine, but I do have to moisten the contacts with a few drops of water.

  22. #22
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    The Edge 500 is extremely accurate when using the wheel sensor, and very accurate when not. When you use it the first time with a wheel sensor you set it to auto-calibrate. It uses GPS to determine the correct wheel size, and then prefers the wheel sensor for speed and distance over GPS data. You could completely lose GPS lock (tunnel, canyons, tall buildings etc.) and still have accurate speed and distance data.

    In fact, with a wheel/cadence sensor installed, GPS is used for very little. Elevation is gathered from the barometric altimeter, although you can set altitude at specific GPS coordinates to assist in accuracy.

    On the other topic, assisted GPS simply means that phones get a faster signal lock using information from cell towers initially while satellites are located. Generally speaking, assisted GPS is preferable over standard GPS. Read up on it here if interested: Assisted GPS - Wikipedia, the free encyclopedia

    As has already been correctly pointed out, the iPhone does in fact have "real" GPS capabilities. Just about any modern smartphone does. However, the GPS on the Edge appears be much more accurate than any smartphone I've used, probably because it only has to incorporate two wireless signals while a smartphone typically has four or more.

  23. #23
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    Quote Originally Posted by scryan View Post
    you can increase accuracy with the cadence/wheel sensor.
    Does this mean that the cadence sensor that comes with the bundle will also read speed and distance with a spoke magnet installed on the rear wheel? If so, does it come with that too?

  24. #24
    sometimereader
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    Quote Originally Posted by jne3 View Post
    Does this mean that the cadence sensor that comes with the bundle will also read speed and distance with a spoke magnet installed on the rear wheel? If so, does it come with that too?
    Don't know what "bundle" you're talking about, but the Garmin Speed/Cadence Sensor GSC10 includes both magnets.
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  25. #25
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    Quote Originally Posted by sometimerider View Post
    Don't know what "bundle" you're talking about, but the Garmin Speed/Cadence Sensor GSC10 includes both magnets.
    I meant the version that comes with the hrm and cadence but I'm pretty sure you answered my question. Thanks.

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