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Discussion Starter · #1 ·
I've been borrowing my brother's forerunner 305 this season and I've never used a computer other than the standard handlebar-mounted speed/time/distance do-hickey.

Initially I liked the 305 because I want to start tracking my HR and graphing my speed/elevation. But after looking at my charts, out of nowhere my HR takes off like a bacon-fueled rubber chicken. The speed reading also seems to go awry sometimes. I don't trust the grade graph but the elevation seems to work. Does anyone else have these problems? I've replaced the battery in the HRM and made sure the unit is fully charged. It's only one year old. WTF?

Here's my latest chart.

ps. I've also noticed the calories burned is WAY too high but I can ignore that.
 

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Yeah, calories burned is often double what it should be.

Likely you're getting interference or the strap isn't picking up correctly. Try one of those conductivity gels and see if it helps.
 

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Interference is relatively rare, but as mentioned poor contact can do it. Positioning usually doesn't matter too much, but you do want it snug, and just under your pecs. Also, I don't know your shape, but sometimes large folk get more accurate readings with the strap on backwards.

FWIW, are you absolutely sure those numbers are BS? Most likely they are, but it's not outside the realm of possibility. Just because you aren't seeing stars doesn't necessarily mean your heart didn't decide to double-time it for a little while.

The grades aren't necessarily all that trustworthy, at least with the smoothing clicked off. The problem is that sudden changes in speed happen faster than the GPS sample rate, and so can make the math work out badly. As long as the unit has had the opportunity to calibrate before heading off, the actual elevation function works pretty well.

And yeah, there could be something wrong with it, too.
 

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well, if you examine the shape of the "BS" HRs, it's at least possible (although unlikely) that the middle one could be legit. By comparison, the ones on the left and right indicate a nearly instantaneous increase -- and corresponding decrease -- in HR from a 'reasonable' rate up to one that appears to be less so; the one in the middle shows a increase/decrease that is not at all instantaneous.

I have an arrythmia, and have often wondered if it is a factor in the occasional spurious readouts I see in my HRM (coincidentally, they are usually in the 220-230 bpm range).
 

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The speed reading on my 705 can get really wacky, but the HRM is usually solid. Nobody has ever told me how to trim out those bad bits of data from the files. It's usually just one data point, but occasionaly it will show speeds in excess of 200mph which makes the whole graph scale wrong.
 

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I have gotten spurious HR data on coolish, dry days when some of my jerseys flapped against my HRM strap. This tended to occur on descents into the wind.

Dancer
 

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Discussion Starter · #10 ·
That's interesting. All three of my HR spikes were on descents. I had a jacket over my jersey but it was still flapping. I'll try turning the HRM strap around. I'm 6'5" 220lbs so I might qualify as 'large folk'

Thanks!
 

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I have found

that for some reason cell phone towers will sometimes cause the HR reading on the Garmin 305 to spike....:confused:
 

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Interesting but I'm guessing your readings aren't total BS.. Since I've been riding with a HR monitor I've been amazed at times. Cruising along thinking I'm going easy and I look down to see my heart rate is in the 170's... Other times when I feel like crap I notice it's in the 130's. Heart rate is influenced by so many factors it's not entirely accurate for training anyhow. Gives you a decent idea but isn't perfect.

If your HR was going fro 130 to 185 to 130 over a super short amount of time I'd call it bs.. but seeing that your graph isn't spiking like that I doubt the edge is messed up. Could be though.. who knows.
 

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Pos?

Sheesh, give the guys a little more credit.

Every HRM I've used gives me whacky "225" spikes sometimes. I am hard to run HRMs on -- I am slender and produce very little sweat.

I have had good luck with electrode contact gel.

Calories burned by any measure other than power is almost a garbage number.

The garmin Edge is cycling-specific, and did a lot better for me than a Forerunner. It's got a speed sensor for the wheel to back up the GPS, and a barometric altimeter to back up the GPS for THAT feature. That corrected a lot of the location data -- cyclists go a lot faster than runners!
 

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The calories are probably high because of the spikes in your heartrate, but don't quote me on that.

I had a multitude of problems with the 305 (all of which are gone with the 705, which is damn near perfect), but the one thing that was stable as a rock was the HR component. Maybe you have a bad strap or something.
 

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ahaid said:
All three of my HR spikes were on descents.
I'm not saying the HR measurement is correct, but that observation would make sense to me. HR is a lagging measurement. I'd expect to see your HR at it's highest as you crest the hill. You've been climbing for awhile, and you're probably starting to shift to a bigger gear as you crest the hill to begin your descent. As you head down the hill, your heart rate begins to drop. How fast depends on your fitness, how much you're pedaling vs. coasting, and how much fear the descent creates.

I wouldn't expect the peaks and valleys of your HR to mirror the peaks and valleys of your speed. I would expect them to be shifted a bit to the right (if that makes any sense).
 

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I've used several of HRMs. The one on my Edge 305 is easily the most reliable and accurate I have used. What else are you comparing it to?

Calories are about 50% high though.
 

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Discussion Starter · #17 ·
I don't have anything else to compare it to. This is my first foray into HRMs. I'm thinking about giving my brother back his Forerunner and buying the Edge.
 

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ahaid said:
I don't have anything else to compare it to. This is my first foray into HRMs. I'm thinking about giving my brother back his Forerunner and buying the Edge.

I would not get too wigged out. As you play with other HRMs you will likely find that they can be finicky and different brands will be finicky in different situations.

I really doubt that the forerunner and the edge will behave much differently from one another.

The more you use any piece of equipment, the more you will learn about what it does well or poorly...and how to maximize its utility. Considering that you have little experience with HRMs and no basis for comparison, it would appear you may have pulled the "P.O.S." trigger a little early?
 

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JustTooBig said:
I have an arrythmia, and have often wondered if it is a factor in the occasional spurious readouts I see in my HRM (coincidentally, they are usually in the 220-230 bpm range).
Tell me more, if you don't mind, about this arrythmia. I am curious about some things I've noted about myself, lately, on a very unpredictable basis. As an FYI, my dad's cause of death was sudden heart arrythmia, which has been about 6 years ago now. Nothing quite like losing a loved one to make you come into reality about your own mortaility.

Thanks for the info, btw...
 
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