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Altimeter Discussion

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  • Altimeter Discussion

    I have owned a Garmin 935 from almost when they 1st came out. Before the 935 I have a Fenix 3 HR, before that a Garmin 920XT and others before.

    I really want to like the the 935, I love the size and weight of it, the battery life, the fit, the operating system and I like the idea of what its meant to do - I say idea of what its meant to do because I find it horribly unreliable. I have a spoken to Garmin support many times and I have even been sent a replacement watch and I have always been on top of updates, but I have no resided the fact that the watch is not very good by design.

    Like everyone else I have massive problems with the Altimeter, every activity I record that is on land I get inaccurate information about altitude. My Altitude may start out correctly (I will often re-calibrate before an activity as its reading wrong), but the activity will always end with -36 or something like that. Why or why Garmin can my watch only use the Altimeter for Altitude? Your cheaper watches use GPS and I have found this far more accurate (my GF's watches she has had).

    9 out of 10 sea swims I will get poor GPS data from, its usually very erratic, it usually looks like its only recorded half the distance or just draws dead straight or erratic lines. I have tried all satellite combinations but no luck. Sea swimming is probably the biggest failure of the watch. My GF's cheaper 735XT usually has no problems with sea swims.

    Any running or cycling activities that might be over 4 hours - there will be a high chance of GPS failures here. GPS may drop signal for 5 - 10 minutes for no reason, in broad day light with no hills or trees in sight. I have also seen my GPS say i'm riding 100kms per hour when i'm stood still. Once again I have not seen these issues on my GFs 735XT. I have tried many different settings and satellite combinations but no good.

    I have a few friends that own this watch but they don't see any issues, but they use their 935's for running and usually nothing longer than a couple hours.

    So why dont I switch to a 735 you ask? Well I need the long capacity of the battery as many of my activities are long distance.

    What do other people use and do that may have the same issues as me? Do you recommend other watches and what watches? The Fenix 3HR I felt too big on my wrist and caused me a bit of pain on my skinny wrists. I have heard the Fenix 5 has problems too, I dont know anything about the Fenix 5 Plus except its very expensive.

  • #2
    i had a 935 a while back when firmware was at 9.60. I had issues with the altimeter and most of the stuff you mentioned so i returned it. then i started to read posts that firmware 9.10 was very stable. so i bought another one because i liked the interface, weight and batteries. i have been very pleased with 9.10 for all the things i do. i do not have Galileo but i live at the beach so i always get a lock very fast with GPS+Glonass. i indoor swim, run, bike, strength and so on. I do not regret the watch. not sure if i'll ever upgrade the firmware. Or at least if i do not see any negatives. I know that some users complain but usually, there is some truth about it. it may not affect everybody but i do not want to take a chance. i have not seen any features from 9.10 to 12.10 that needs the update. firstbeat technology is still the same and that is what's important. I am not sure if you can downgrade to 8.0 like it used to be if your firmware is higher than 11. So bottom line, i am very happy with the 935 right now.


    • #3
      My experience, and that of others I know is very much at odds with yours. Activity durations from 10 mins to 14 hours without issue on trails and on road, running and cycling. Sea swims generally good almost from the first one over 18months ago. There was a time when they weren't so good but definitely good now - and for example, with the latest GPS and firmware updates.

      I don't believe the 935 is a terrible watch. For some reason you've had a terrible experience with a good watch.
      Last edited by philipshambrook; 01-10-2019, 10:33 PM.


      • #4
        I had altimeter issue, garmin support replace my watch and at the moment all is ok


        • #5
          Ring Garmin support, sounds like your watch is faulty. Is it still in warranty?

          I had some issues with mine, but the watch was swopped. I looked long and hard at other options, IMHO there is nothing out there that has the size/weight and features of the 935. The Sunnto 9 looked very promising, but doesn't do ANT+, was 30g heavy than the 935, much bigger and also didn't do Strava live segments when I looked a few months back. The Spartan TRAINER HR also looked promising, but once again didn't do Ant+ and got some dreadful reviews for OW performance!


          • #6
            Originally posted by Pierrotsc View Post
            (cut) firmware 9.10 was very stable. (cut)
            if only 935 were upgraded directly from 9.10 to 12.10... 9.60 was the worst firmware nightmare i've seen in 7 years of Garmin watches and 15 years of Garmin handheld GPS, no wonder if someone still complain. at the moment, 935 is doing reasonably well what i need (70.3 and 140.6 triathlon, ultratrail, marathon), but last "summer of crazy gps firmware" was hard to stand.


            • #7
              OperationOne are you now using 12.10 FW ? Is it ok for OWS swimming?


              • #8
                actually ows accuracy it's not related to the fw but to the gps fw - once 2.30 got out, gps got basically fixed - and since i was quite happy with how the watch tracked ows; so - 12.10 + 2.30 are doing a good...


                • #9
                  Is it ok for OWS swimming?
                  See post #3 above.

                  BTW, I think it's a combination of the GPS and the firmware. In the past firmware updates have changed the OWS recording in the absence of a change to GPS.


                  • #10
                    Originally posted by Jinx View Post
                    OperationOne are you now using 12.10 FW ? Is it ok for OWS swimming?
                    yes, my last OWS and my last triathlon races have been properly recorded with fw and GNSS (gps+galileo) available (both AFTER the 9.60 + galileo mad release)


                    • #11
                      Originally posted by vertvorb View Post

                      Like everyone else I have massive problems with the Altimeter, every activity I record that is on land I get inaccurate information about altitude.
                      Not everyone. My altimeter works fine. I never had the OWS issue either. But to be fair, I didn't have very many of those activities this past summer. I haven't done a 4 hr plus run with this watch, but I have several cycling rides that passed that mark. No issues with GPS or sensor loss. It's odd you've had two 935's with these issues and I don't have any recommendations for a replacement. My 935 has worked great for me and it is the watch I'd recommend to someone who uses it the way you do.


                      • #12
                        you are lucky to have altimeter working fine.
                        Mine is always giving bad information. I will then recontact Garmin support if it is a harware problem. I always thought it was sofware bug.
                        You can see enclosed my last run with altitude comparison between the watch and real altitude. light green is watch altitude. I finished my run with almost 100m more than the starting point on the same place. I had in parallel another altimeter without any problem so no variation of barometric pressure during this run that could explain such a variation. We can nevertheless see that the altitude profile is quiet corresponding but with an increasing offset ... forerunner 935 - problème altimètrejpg.jpg
                        Last edited by Steph74-74; 01-12-2019, 02:42 PM.
                        Forerunner 935 my first ewatch


                        • #13
                          Steph74-74 I disagree. Before you dismiss my response, please hear me out. I was seeing off altitude readings when I first got my 935 which confused me too. After raising questions on this forum, I was enlightened on how a barometric altimeter works from a fellow forum user and decided to do my own research. After the 16:40 minute of your graph, your altitude changed between devices, but the difference in altitude between the two was the same and gradually climbed at the same rate for the remainder of your activity. This tells me the two had a different barometric reading from the 16:40 point on. Your graph is too symmetrical to suggest otherwise.
                          Last edited by TMK17; 01-12-2019, 05:46 PM.


                          • #14
                            TMK17, I do not understand the end of your answer.
                            I know how a barometric altimeter works and as I said in my post I had another barometric altimeter during my run to check the difference between the watch and the other one.
                            If barometric pressure lowers during the run. It might explain this increase in altitude. A variation of 12 or 13 mb could explain this increase of 100meter . (1mb = 8.3 meter). but the weather was constant during my run. Weather forecast was not announcing any big pressure variation in the area of the run and the other barometric altimeter give the same altitude at the end of the run that the starting altitude of the circuit.
                            With this information, I think I don't do any mistake concluding that the altimeter of the watch is having problem. It is either barometric pressure accuracy of the probe that is not good or some pressure misreading due to the position of the probe inside the watch.
                            I agree that it is not completely wrong because the shape of the curve is quiet correct. Perhaps Garmin can help explaining us what could happen.
                            Forerunner 935 my first ewatch


                            • #15
                              I will say the same as I have said in a number of other threads: Start by enabling Ambient Pressure in a data field. (Not Barometric Pressure). This is the key to understanding what is going on.

                              If you are at the same altitude at the end and start of your workout, and you know from other sources that the air pressure at that altitude did not change during that time, two things can have happened:

                              1. If the Ambient Pressure datafield shows another value after the workout, then you have a sensor problem of some sort.

                              2. If the Ambien Pressure datafield shows the same Value after the workout, and you have another altitude reading, then you probably also have another Barometric Pressure reading. In this case, the firmware in the watch did some wrong guesses about the reason for the changes in ambient pressure during the run, thinking that some of them were caused by a general change in air pressure while they were in fact caused by an altitude change, or vice versa.

                              Without the information about the Ambient Pressure reading, every attempt of finding the reason is guesswork. And in most threads it stays at the guesswork, because people aren't really interested in finding out what is happening.