Heart rate is wrong in 2km first!
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 I don’t have a 5, but do you wait until you get a good read? I usually wait a bit longer than the icon getting green. 
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 @isazi i alway wait for ready ( heart icon and gps icon are green) and then ran. 
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 How are you wearing the watch? Loose or tight? Where on the arm? Hot or cold weather? 
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 @hieus try staying on the ‘start’ screen (when you get the gps and heart locks) for a couple of minutes, i.e. from when you put your shoes on instead of when you’re out. I had the same issue than you (with a S9 though), and that solved it 
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 I had the exact same behaviour with an Ambit3 and HR strap, I presumed that the strap is starting to fail, but this is interesting if you get the same with optical sensor too. Now I’m confused: maybe my strap isn’t failing (I need to measure the resistance then) and something strange is happening when data is interpreted by SA?! 
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 If you don’t see something like this after you take your watch off, it’s too loose. Also, as others mentioned, have ohr on (workout start screen) during your preparation, warmup, etc. 5 minutes before hitting “start” should be enough. Shaving wrist also helps but for some people it’s too hardcore  
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 @Łukasz-Szmigiel I guess then I need to shave my chest  
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 @andrasveres yeah I’ve heard about some furry runners that have problems with chest straps but I was referring to the original poster  As with hr strap - I’d check the battery first or maybe the belt is worn out. 
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 @Łukasz-Szmigiel Just kidding.  
 Regarding the strap: battery change was the first thing done, with no result. Planning to buy a Polar H10 as Suunto straps tend to start fail in no time.
 Sorry for the off topic.
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 @Egika said in Heart rate is wrong in 2km first!: Where on the arm I wear it on my left wrist and tight, the weather is so hot (Hanoi, Vietnam weather) 
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 @jw-cou yep, i will try with your tip. 
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 Had the same experience too. Have a Ssu and have to use hr belt. If you want a precise measurement use a hr belt. I had 2 suunto hr belts and - excuse me - they are rubbish. Suunto can’t that. So I bought a H10 and I’m pretty satisfied. No problems at all. It’s worth the money if you want reliable hr data 
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 @Stefan-Kersting there are new belts and improved ones though. If you still have a warranty ask for a replacement. They are white on the sensor buckle. 
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 @Dimitrios-Kanellopoulos ok then my comment applies just the older ones. Don’t have experience with the new ones. I don’t have warranty any more but happy with the polar  
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 @Stefan-Kersting I know pal, just saying  
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 New belts have a different problem, they evaporate quickly from suunto store. 
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 @lexterm77 yes and manufacturing is slow due to Corona. Difficult times for EU factories etc 
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 I bought two just in case this coronaverse shit hits the fan. 
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 @jw-cou I tried as your idea but the first 2km heart rate was still wrong 
  
 
 
