Go Back  Bike Forums > Bike Forums > General Cycling Discussion
Reload this Page >

Heart rate montitor goes wonky at the same spot

Notices
General Cycling Discussion Have a cycling related question or comment that doesn't fit in one of the other specialty forums? Drop on in and post in here! When possible, please select the forum above that most fits your post!

Heart rate montitor goes wonky at the same spot

Old 08-07-22, 12:43 PM
  #1  
lenticular
Newbie
Thread Starter
 
Join Date: Mar 2007
Posts: 32
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked 1 Time in 1 Post
Heart rate montitor goes wonky at the same spot

Near the end of my rides, I climb a fairly steep hill. I ride with a Garmin Edge 520 and a Garmin HRM. As I approach the hill, my heart rate is, say, 144. I start up the hill and watch my HR climb through the 150's into the 160's. Then, at the same spot every ride, my heart rate shows as dropping even though the hill remains steep. Suddenly my HR is displayed as being in the 140's, then falls through the 130's, and today it hit 112. I crest the hill, and my HR shows a believable 158.

The funny thing is that this happens at the same spot on the hill every time. As I climb, my breathing, and the effort it takes to get up the hill tell me that, yes, it is quite steep. There are no overhead powerlines, but I wonder about a Navy research facility about a mile away. I looked for HR deviation on the outbound leg, when I descend the hill, but I'm moving so fast that I'm only there for a few seconds and all is normal. The HRM is otherwise reliable.

Isn't that weird?
lenticular is offline  
Old 08-07-22, 01:21 PM
  #2  
rsbob 
Sniveling Weasel
 
rsbob's Avatar
 
Join Date: Sep 2020
Location: Seattle-ish
Posts: 2,938
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1065 Post(s)
Liked 1,979 Times in 1,144 Posts
Either it is electrical interference by the Navy, a software glitch, or your HRM strap is going south. I have Garmin as well and my strap started sending wonky readings to the transceiver unit. I would be riding along and my heart rate would show 115 when I knew it should be above 130. If it starts to happen in other places, replace the strap. If that is the sole place, its EMI.
__________________
Immoderate Cyclist “No regerts”



rsbob is offline  
Old 08-07-22, 01:42 PM
  #3  
Barry2 
LR÷P=HR
 
Join Date: Sep 2019
Location: SF Bay Area
Posts: 1,545

Bikes: Holdsworth 1979 Special, C-dale 1993 MT3000 Tandem & 1996 F700CAD3, Cervelo 2022 R5 & 2018 R3, JustGo Runt, Ridley Oval, Kickr Bike 8-)

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 595 Post(s)
Liked 751 Times in 436 Posts
BT interference

My Garmin speed sensor drops out every time I cross a particular bridge.
It's got to the point I'd worry if it didn't!

2.4GHz has become quite a crowded band.

Barry
Barry2 is offline  
Old 08-07-22, 02:30 PM
  #4  
cyclezen
OM boy
 
cyclezen's Avatar
 
Join Date: Jul 2005
Location: Goleta CA
Posts: 4,122

Bikes: a bunch

Mentioned: 10 Post(s)
Tagged: 0 Thread(s)
Quoted: 420 Post(s)
Liked 482 Times in 334 Posts
Electrical inteference...
Same thing happens to my HRM and cell on a stretch of road where there are some overhead major transmission lines... Both devices go wacko and the HRM eventually shuts off, because the lines are there for 3/4 mile... All leads to/from the Ellwood Peaker Plant - which actually is running fulltime 100%,
Super unhealthy for residents in a new, upscale development just a 100 yds away...
Can also happen with underground lines.
Ride On
Yuri
cyclezen is offline  
Old 08-07-22, 03:18 PM
  #5  
_ForceD_
Senior Member on Sr bikes
 
_ForceD_'s Avatar
 
Join Date: Jul 2015
Location: Rhode Island
Posts: 1,912

Bikes: Several...from old junk to new all-carbon.

Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 832 Post(s)
Liked 520 Times in 284 Posts
Can you give the name and/or location of the Naval research facility?

Dan
_ForceD_ is offline  
Old 08-07-22, 04:14 PM
  #6  
Iride01 
MotuekaCascadeChinook
 
Iride01's Avatar
 
Join Date: Jul 2017
Location: Mississippi
Posts: 11,482

Bikes: Tarmac Disc Comp Di2 - 2020

Mentioned: 43 Post(s)
Tagged: 0 Thread(s)
Quoted: 4665 Post(s)
Liked 3,163 Times in 2,204 Posts
How old is your strap. You'd think it'd be random time for worn out straps, but certain things might trigger them to misbehave. And perhaps it's the battery getting low and that's about the time it can draw current fast enough before the voltage goes too low. The rest periods between rides just let the battery get a second breath and once again be able to supply the required current and voltage for a short time.

Possibly it's some dastardly ray the aliens from outer space are using to observe the goings on at the Naval facility! <grin>
Iride01 is offline  
Old 08-07-22, 05:20 PM
  #7  
lenticular
Newbie
Thread Starter
 
Join Date: Mar 2007
Posts: 32
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked 1 Time in 1 Post
The facility is SPAWAR on Pacific Highway in San Diego. The hill where the HRM goes wonky is Presidio Drive. There is probably no connection, but I recall living next to an Air Force base where peoples' garage doors would open mysteriously from time to time.

Since the indicated HR is always slower, never faster, than the actual, I would guess that packets are being dropped between the strap and the computer, but not so many as to make the computer decide that there is no HRM connected.
lenticular is offline  
Old 08-07-22, 07:17 PM
  #8  
koala logs
Banned.
 
Join Date: May 2022
Posts: 674
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 347 Post(s)
Liked 166 Times in 136 Posts
Never ride close to a navy or air force research facility. Next time you might end up with sore butt and you have have absolutely no clue how it happened.
koala logs is offline  
Old 08-08-22, 06:49 AM
  #9  
pdlamb
Senior Member
 
Join Date: Dec 2010
Location: northern Deep South
Posts: 7,783

Bikes: Fuji Touring, Novara Randonee

Mentioned: 33 Post(s)
Tagged: 0 Thread(s)
Quoted: 2018 Post(s)
Liked 1,263 Times in 805 Posts
Originally Posted by lenticular View Post
The facility is SPAWAR on Pacific Highway in San Diego. The hill where the HRM goes wonky is Presidio Drive. There is probably no connection, but I recall living next to an Air Force base where peoples' garage doors would open mysteriously from time to time.
I'm only slightly surprised, if the source is at SPAWAR, they're not doing a better job containing or shielding the source. Are there any funny-shaped towers or radomes at the airport near that spot in the road?
pdlamb is offline  
Old 08-08-22, 08:16 AM
  #10  
genejockey 
Klaatu..Verata..Necktie?
 
genejockey's Avatar
 
Join Date: May 2007
Location: SF Bay Area
Posts: 11,846

Bikes: Litespeed Ultimate, Ultegra; Canyon Endurace, 105; Battaglin MAX, Chorus; Bianchi 928 Veloce; Ritchey Road Logic, Dura Ace; Cannondale R500 RX100; Schwinn Circuit, Sante; Lotus Supreme, Dura Ace

Mentioned: 38 Post(s)
Tagged: 0 Thread(s)
Quoted: 6557 Post(s)
Liked 6,908 Times in 3,538 Posts
Years ago, with a Polar HRM, when I turned onto one road at the base of a climb, my HRM would suddenly show numbers in the 220s. The first time I saw that, I almost panicked! Then I thought to stop and check my pulse, which was about half of that. I realized there was something there that was screwing with the signal.
__________________
"Don't take life so serious-it ain't nohow permanent."

"Everybody's gotta be somewhere." - Eccles
genejockey is offline  
Old 08-12-22, 06:43 AM
  #11  
Speedskater
Full Member
 
Speedskater's Avatar
 
Join Date: Jun 2007
Location: Cleveland
Posts: 349

Bikes: Bob Jackson, Trek & Sampson

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 29 Post(s)
Liked 4 Times in 2 Posts
In the distant past, I too have seen a Polar HRM jump to about 220, with no obvious reason.
Speedskater is offline  
Old 08-12-22, 09:39 AM
  #12  
genejockey 
Klaatu..Verata..Necktie?
 
genejockey's Avatar
 
Join Date: May 2007
Location: SF Bay Area
Posts: 11,846

Bikes: Litespeed Ultimate, Ultegra; Canyon Endurace, 105; Battaglin MAX, Chorus; Bianchi 928 Veloce; Ritchey Road Logic, Dura Ace; Cannondale R500 RX100; Schwinn Circuit, Sante; Lotus Supreme, Dura Ace

Mentioned: 38 Post(s)
Tagged: 0 Thread(s)
Quoted: 6557 Post(s)
Liked 6,908 Times in 3,538 Posts
In addition to the jump into the 220 range at the same spot repeatedly, I remembered another anomaly - PG&E put come high voltage cables underground along one of my favorite routes, and if I rode directly over them, my HR reading would drop to zero. I can tell you, the first time you see that it's a little freaky!

I played around with the range of the effect and found if I was > 6 feet away from the center of where the cables were buried, my HRM readings returned to normal. That was using a simple Polar HRM, and I was using wired cadence and speed sensors and a Cateye cyclocomputer. Later I got a Garmin with wireless sensors AND HRM, and riding along the same stretch, my indicated speed jumps all over the place - up and down 2 or more mph. I think the electromagnetic field around the cables is disrupting the speed sensor signal and the Garmin is switching back and forth between that and the GPS for my speed. That's my guess, anyhow.
__________________
"Don't take life so serious-it ain't nohow permanent."

"Everybody's gotta be somewhere." - Eccles
genejockey is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.