Grade Field Errors, My explaination

I tried to reply to a previous discussion about this but it was locked.   I saw a comment about going up or down a hill and the Gradient field not being accurate or slow to show the change.  The 1030 Plus, unlike previous models, does not seem to have a barometric altimeter.  Because of this, it relies 100% on GPS to determine the rate of climb or descent. GPS is pretty accurate in showing your horizontal position, within 10-30 feet or so, depending on conditions.  However, if you are talking about 10-30 feet horizontal, that makes the grade field not so accurate. I am sure most of you have experienced on a big climb then topping the hill and starting the downside the grade still shows you climbing.  Without that barometric altimeter, it makes it slower to react.

Another thing about the grade field, from what I have read and what I have experienced, the Garnins calculates the grade this way. 

It records your position every second or so, and then at some predetermined time or distance, it compares your current position to that past position.  It knows how much horizontal distance you have gone and how much altitude you have gained or lost to calculate your grade, plus or minus. That is why your display of grade is always 10-30 feet behind you, depending on your speed.  If you are going up a short/steep hill, and then going down the other side, your display may not even show a hill. Plus, I do not know what the refresh rate is for the display. 

Go up that same hill very slowly, then you will get a more accurate display.  

Many years ago I asked Garmin support about this this and what the "predetermined time or distance" was.  She confirmed that I was correct about how the grade field worked, but she did not know the exact algorithm they used, and it was probably a trade secret anyway.

Just my 2 cents worth.

  • Garmin regional web sites still selling new 1030 Plus have a big tick in the “specs” section against Barometric Altimeter ?

  • Actually, having seen the 1030+ being still sold new by Garmin, it’s a bit surprising they are still sold new almost 2 years after the 1040 was released and for the same price as the standard 1040 and the 1030+ has not had a software release for 12 months and likely never, must be a big demand from users who believe they are better, does Garmin have a big warehouse full of them or still making them?

  • Edge 1030+ definitly has a barometer chip - even normal Edge 1030 has one!

    The  strange thing is, that the normal Edge 1030 reacts more fast to elevation changes than the 1030+ does - although it has a better Bosch chip as normal 1030.

    The main problem of grade display delay imho is, that the change of elevation display has a huge delay.

    I now have the Edge 1040 and am satisfied - although there are many complaints about this device too.

  • I have looked at the 1040 and there are a few features that might be nice.  But, may not be worth $600 US when my 1030+ still worked without issues.  One of the features that the 1040 is missing the the ability to transfer routes to other Garmins wirelessly, which is sometimes tricky, but I use a lot. I do wish they would do more software updates.

    Now if I was getting my first Garmin or upgrading from a much older Garmin, then the 1040 is a no-brainer. 

  • I went from a 530 to the 1040 (non-solar) as my eyes are not what they used to be and I had a major birthday (also with a zero at the end) coming up, previous to 530 I had 200, 510, 520 so the 1040 huge screen was great (even though they don't make best use of it IMO) and the battery is amazing (I get 80-100 hours, with battery usage settings that might be too much for many users). If my previous device was a 1030/1030+ I think I might have been disappointed as the hardware upgrade (screen/battery) is significant (IMO) but the software is maybe a backward or at least side step, for me at least as I don't use most performance / social features, I just ride...

    Given the still large crop of "issues" (and seemingly growing with each release) and the fact that in June it has been out for 2 years if I had a 1030+ I was happy with I would be sitting out the 1040 and awaiting a 1050  in a year or two?

    PS I would also give the solar a miss, the less bright screen is a big negative and the battery benefits are not worth the extra $$

  • While Garmin's exact algorithm for calculating grade may remain a proprietary secret, your discussion provides useful context for users seeking to understand the limitations and behavior of their devices more deeply. Thanks for sharing your insights and experiences!


  • The 1030 Plus, unlike previous models, does not seem to have a barometric altimeter.

    What makes you think it doesn't have a barometer?

    The spec sheet says it has one. Why didn't you check the spec sheet?