hac4 computer loses heart rate on descents

[Andrew Smit]

Recently purchased a HAC4.

I've been using it for a couple of weeks now and find that on descents
, the hear rate readings either jump around wildly or just stay on
zero.

The problem also seems to occur when riding fast on the flats.

It is almost as if the receiving unit is unable to process the data
it is receiving quickly enough - from the wireless transmitter on
the fork and the heart rate monitor chest strap . I have moved the
fork-mounted transmitter as close to the rim as possible to shorten
the distance between bar-mounted receiving unit and the
trasmitter but this did not seem to improve things.

The speed readings are also flakey when riding > 25 mph. I do have
another magnet and a wired speedo on my front wheel (on the right
side - the HAC4 is mounted on the left) - i don't know if this could
be an issue.

When riding at moderate speeds , Heart Rate and speed data seemes
reliable.

I haven't yet tried changing batteries of cleaning contacts - odd that
it is only when going fast that this is an issue.

Any help appreciated

 

[Terry Morse]

Andrew Smit wrote:

> Recently purchased a HAC4.
>
> I've been using it for a couple of weeks now and find that on descents
> , the hear rate readings either jump around wildly or just stay on
> zero.
>
> The problem also seems to occur when riding fast on the flats.

I have a Polar 720, not a HAC4. But I see the same problem on
descents, which for me is caused by the chest transmitter contacts
drying out. I now use electrode cream on the contacts, which almost
always prevents this problem from happenning:

http://froogle.google.com/froogle?q=signa cream

--
terry morse Palo Alto, CA http://bike.terrymorse.com/

 

[Francesco Devittori]

Terry Morse wrote:
> Andrew Smit wrote:
>
>
>>Recently purchased a HAC4.
>>
>>I've been using it for a couple of weeks now and find that on descents
>>, the hear rate readings either jump around wildly or just stay on
>>zero.
>>
>>The problem also seems to occur when riding fast on the flats.
>
>
> I have a Polar 720, not a HAC4. But I see the same problem on
> descents, which for me is caused by the chest transmitter contacts
> drying out. I now use electrode cream on the contacts, which almost
> always prevents this problem from happenning:
>
> http://froogle.google.com/froogle?q=signa cream
>
> --
> terry morse Palo Alto, CA http://bike.terrymorse.com/

I have a Polar A5 (fairly basic model, no coded transmitter) and on
descents, fast flats or strong wind it shows the same problem: 0 or 200+
bpm. It's annoying, I never thought it could be the contacts drying out
but it seems logic.
I'll try next time!

 

[Michael J. Klein]

On 28 Jun 2004 13:54:40 -0700, [email protected] (Andrew
Smit) wrote:

>Recently purchased a HAC4.
>
>I've been using it for a couple of weeks now and find that on descents
>, the hear rate readings either jump around wildly or just stay on
>zero.
>
>The problem also seems to occur when riding fast on the flats.
>
>It is almost as if the receiving unit is unable to process the data
>it is receiving quickly enough - from the wireless transmitter on
>the fork and the heart rate monitor chest strap . I have moved the
>fork-mounted transmitter as close to the rim as possible to shorten
>the distance between bar-mounted receiving unit and the
>trasmitter but this did not seem to improve things.
>
>The speed readings are also flakey when riding > 25 mph. I do have
>another magnet and a wired speedo on my front wheel (on the right
>side - the HAC4 is mounted on the left) - i don't know if this could
>be an issue.
>
>When riding at moderate speeds , Heart Rate and speed data seemes
>reliable.
>
>I haven't yet tried changing batteries of cleaning contacts - odd that
>it is only when going fast that this is an issue.
>
>Any help appreciated

At Cybex, we found that a person running on a treadmill over 6 to 7
mph could not have his heartrate reliable measured by contact due to
muscle noise. We did not find that to be true on the chest strap
system. I wonder if the dynamics of biking create more muscle noise
than running and its interfereing with the pickup system. Hmmm

Michael J. Klein [email protected]
Dasi Jen, Taoyuan Hsien, Taiwan, ROC
Please replace mousepotato with asiancastings
---------------------------------------------

 

[Andrew Smit]

While out riding this weekend, I spoke to a guy who also had a HAC4
but didn't report any heart rate reading issues on descents. He did
say he used the electrode gel.

I'll give the gel a try too although since my problem is so quick to
occur on a descent, I can't believe the sweat from the transmitter has
time to dry out and then start working again as soon as I hit the
flats.

I have replaced all the batteries (except the chest transmitter
since the unrelaible HR readings are also a problem when I use a
polar chest transmitter ) - I'll see if that fixes the problem first.

If those things don't work, I'll experiment removing the other wheel
magnet (not sure if that is somehow effecting things), riding without
cell phone/blacberry (?) and riding with the HAC4 strapped to the
handlebar but not mounted on the receiving unit.



Francesco Devittori <frenkatfrenkdtcm> wrote in message news:<[email protected]>...
> Terry Morse wrote:
> > Andrew Smit wrote:
> >
> >
> >>Recently purchased a HAC4.
> >>
> >>I've been using it for a couple of weeks now and find that on descents
> >>, the hear rate readings either jump around wildly or just stay on
> >>zero.
> >>
> >>The problem also seems to occur when riding fast on the flats.
> >
> >
> > I have a Polar 720, not a HAC4. But I see the same problem on
> > descents, which for me is caused by the chest transmitter contacts
> > drying out. I now use electrode cream on the contacts, which almost
> > always prevents this problem from happenning:
> >
> > http://froogle.google.com/froogle?q=signa cream
> >
> > --
> > terry morse Palo Alto, CA http://bike.terrymorse.com/
>
> I have a Polar A5 (fairly basic model, no coded transmitter) and on
> descents, fast flats or strong wind it shows the same problem: 0 or 200+
> bpm. It's annoying, I never thought it could be the contacts drying out
> but it seems logic.
> I'll try next time!

 

[Blair P. Houghton]

Michael J. Klein <[email protected]> wrote:
>At Cybex, we found that a person running on a treadmill over 6 to 7
>mph could not have his heartrate reliable measured by contact due to
>muscle noise. We did not find that to be true on the chest strap
>system. I wonder if the dynamics of biking create more muscle noise
>than running and its interfereing with the pickup system. Hmmm

About 18 months (and 40 lbs) ago, I had a treadmill test
at my doctor's office.

Total washout. Saw maybe one good P-wave in a 5-minute
walk.

Flab is a terrible medium for efficient collection of
coordinated electrical signal data. The constant motion
of the electrodes and the slightly larger distance from
the signal source (the heart) and strange impedance
seems to send even expensive EKG machines into the weeds.

So maybe there's some of that in what you saw. Unless you
hire real bikies with 0.8% bodyfat. Muscle noise will
definitely get involved, too.

However, it sounds a lot like the problem that began this
thread is due to the increased input rate. Either the
pulses from the wheel sensor are coming in too fast to be
polled, or they're driving interrupts too fast for the CPU
to keep up. Either way, you're going to lose something.

Makes me leery of getting a combo heart/bike computer, now.

--Blair
"For 80 bucks, I want the thing
to automatically download security
patches..."

 

[Terry Morse]

Blair P. Houghton wrote:

> However, it sounds a lot like the problem that began this
> thread is due to the increased input rate. Either the
> pulses from the wheel sensor are coming in too fast to be
> polled, or they're driving interrupts too fast for the CPU
> to keep up. Either way, you're going to lose something.
>
> Makes me leery of getting a combo heart/bike computer, now.

All of the heart monitors seem to have the same problem, combo or
not. Blame it on RF interference or a poor skin-strap contact.
--
terry morse Palo Alto, CA http://bike.terrymorse.com/

 

[Tim McNamara]

IME heart rate monitors don't work well on windy days, descents, etc.
I've never tracked down the cause, and since I don't use them any more
I am not very motiated. I always suspected that it was simply the
wind drying out the contact between the transmitter belt and my skin,
since this did not happen in the winter when I was riding bundled up
and hence was very sweaty, and it never happened on rollers or
trainers. You can get some electrolytic gel for improving the contact
with the skin at many pharmacies- that might solve the problem.

 

[H. Morgan]

On Thu, 22 Jul 2004 19:04:01 -0500, Tim McNamara
<[email protected]> wrote:

>IME heart rate monitors don't work well on windy days, descents, etc.
>I've never tracked down the cause, and since I don't use them any more
>I am not very motiated. I always suspected that it was simply the
>wind drying out the contact between the transmitter belt and my skin,
>since this did not happen in the winter when I was riding bundled up
>and hence was very sweaty, and it never happened on rollers or
>trainers. You can get some electrolytic gel for improving the contact
>with the skin at many pharmacies- that might solve the problem.


The signal from the pickup gets blown out behind you before the
receiver can pick it up when you are going really fast. I think,
anyway. Maybe. Yup, that's gotta be it. You could have the guy behind
you wear your receiver and yell out your heart rate to you.