Polar Power/720i Cadence magnet problem

[Michael Hathawa]

Today, in a race, something happened to "shut down" the cadence function. The 720i stopped
displaying cadence/power after that point, while HR, speed and clock continued to perform . After
the race, I dis-assembled the caence magnet from the crank, and tried "flashing" it by the power
strip (on the chainstay), and I am not getting any reading. Is it possible to either a) break the
magnet, or b) break the cadence part only of the power strip? (I don't know the actual name of the
"power strip" part on the chainstay).

Any other ideas/suggestions would be greatly appreciated. Otherwise, it is off to the bikestore to
try to replace the cadence magnet, hoping to solve the problem.

Thanks, Mike Hathaway

 

[N2vx Jim]

On Sun, 18 Jan 2004 23:11:41 GMT, Michael Hathaway
<[email protected]> wrote:

>Today, in a race, something happened to "shut down" the cadence function. The 720i stopped
>displaying cadence/power after that point, while HR, speed and clock continued to perform . After
>the race, I dis-assembled the caence magnet from the crank, and tried "flashing" it by the power
>strip (on the chainstay), and I am not getting any reading. Is it possible to either a) break the
>magnet, or b) break the cadence part only of the power strip? (I don't know the actual name of the
>"power strip" part on the chainstay).
>
>Any other ideas/suggestions would be greatly appreciated. Otherwise, it is off to the bikestore to
>try to replace the cadence magnet, hoping to solve the problem.
>
>Thanks, Mike Hathaway

How strong is the magnet? I've seen some that are marginal. Replacing with a chunk of rare earth
magnet helped.

Jim

 

[Michael Hathawa]

On Mon, 19 Jan 2004 03:18:04 GMT, "Jim, N2VX"
<[email protected]> wrote:

>On Sun, 18 Jan 2004 23:11:41 GMT, Michael Hathaway <[email protected]> wrote:
>
>>Today, in a race, something happened to "shut down" the cadence function. The 720i stopped
>>displaying cadence/power after that point, while HR, speed and clock continued to perform . After
>>the race, I dis-assembled the caence magnet from the crank, and tried "flashing" it by the power
>>strip (on the chainstay), and I am not getting any reading. Is it possible to either a) break the
>>magnet, or b) break the cadence part only of the power strip? (I don't know the actual name of the
>>"power strip" part on the chainstay).
>>
>>Any other ideas/suggestions would be greatly appreciated. Otherwise, it is off to the bikestore to
>>try to replace the cadence magnet, hoping to solve the problem.
>>
>>Thanks, Mike Hathaway
>
>How strong is the magnet? I've seen some that are marginal. Replacing with a chunk of rare earth
>magnet helped.
>
>Jim

Well, I bought a new magnet (though not a super powerful one). I tested that it would trigger the
light on the power strip (it did), and I attached it to the crank arm. It registered on the power
strip AND on the 720i monitor - for a minute or so. After a minute, it stopped registering. I tried
to move it around (thinking it had slipped/moved), but it no longer registered. After taking it off
the crank arm, I tried it and the original magnet, but neither of them will even trigger the light
on the power strip.

Question: is it possible to have a broken cadence reader in the power strip? (the speed meter -
magnet on the wheel still works and registers.) I am bummed because all of my trainer and road
workouts are power-based.

Thanks to anyone who can help, Mike

 

[Matt J]

> Question: is it possible to have a broken cadence reader in the power strip? (the speed meter -
> magnet on the wheel still works and registers.) I am bummed because all of my trainer and road
> workouts are power-based.
Perhaps the battery is shot? Make sense if it stops working after a minute or so, I suppose Matt

 

[Per Elmsäter]

Michael Hathaway wrote:
> Well, I bought a new magnet (though not a super powerful one). I tested that it would trigger the
> light on the power strip (it did), and I attached it to the crank arm. It registered on the power
> strip AND on the 720i monitor - for a minute or so. After a minute, it stopped registering. I
> tried to move it around (thinking it had slipped/moved), but it no longer registered. After taking
> it off the crank arm, I tried it and the original magnet, but neither of them will even trigger
> the light on the power strip.
>
> Question: is it possible to have a broken cadence reader in the power strip? (the speed meter -
> magnet on the wheel still works and registers.) I am bummed because all of my trainer and road
> workouts are power-based.
>
> Thanks to anyone who can help, Mike

Are you sure it wasn't just the LED quit flashing after a minute or so? I just mounted the original
LED a couple of days ago from my new Polar Power package and I have no problems. Even though the
magnet is almost 10 mm away from the sensor. It didn't work until I mounted it on the top of the
crankarm. I had it on the botom at first and that did not work. What you have to be aware of is that
the LEDs will only blink for the first 50 revolutions of your crank or wheel. After that the LEDs go
out, but you will of course be able to monitor your cadence and speed on your S720i display. You
will have to completely stop pedaling and rolling your tire for a minute or more before the LEDs
once again will signal activity.

BTW do you ever see a yellow LED blinking indicating that the chainspeed sensor is active? I see a
red and green LED but no yellow. However the red LED blinks in places where the magnet on the wheel
is not active. This makes me suspect that there is no yellow LED, but two red and a green???

--
Perre

You have to be smarter than a robot to reply.

 

[Per Elmsäter]

Per Elmsäter wrote:
> Michael Hathaway wrote:
>> Well, I bought a new magnet (though not a super powerful one). I tested that it would trigger the
>> light on the power strip (it did), and I attached it to the crank arm. It registered on the power
>> strip AND on the 720i monitor - for a minute or so. After a minute, it stopped registering. I
>> tried to move it around (thinking it had slipped/moved), but it no longer registered. After
>> taking it off the crank arm, I tried it and the original magnet, but neither of them will even
>> trigger the light on the power strip.
>>
>> Question: is it possible to have a broken cadence reader in the power strip? (the speed meter -
>> magnet on the wheel still works and registers.) I am bummed because all of my trainer and road
>> workouts are power-based.
>>
>> Thanks to anyone who can help, Mike
>
> Are you sure it wasn't just the LED quit flashing after a minute or so? I just mounted the
> original LED a couple of days ago from my new

I meant of course to say that I mounted the original magnet, not LED.

> Polar Power package and I have no problems. Even though the magnet is almost 10 mm away from the
> sensor. It didn't work until I mounted it on the top of the crankarm. I had it on the botom at
> first and that did not work. What you have to be aware of is that the LEDs will only blink for the
> first 50 revolutions of your crank or wheel. After that the LEDs go out, but you will of course be
> able to monitor your cadence and speed on your S720i display. You will have to completely stop
> pedaling and rolling your tire for a minute or more before the LEDs once again will signal
> activity.
>
> BTW do you ever see a yellow LED blinking indicating that the chainspeed sensor is active? I see a
> red and green LED but no yellow. However the red LED blinks in places where the magnet on the
> wheel is not active. This makes me suspect that there is no yellow LED, but two red and a green???

--
Perre

You have to be smarter than a robot to reply.

 

[Paulus]

The LED flashes for the 1st minute to show it is sensing the magent. After that it stops flashing
and needs to received no signal for about 10 minutes before it flashes again.

Overhead powerlines and traffic signals tend to make my s720i start and stop as well as give me huge
HRM's, speeds and cadences. Being 'dead' and doing 150kph is most annoying!

P

"Michael Hathaway" <[email protected]> wrote in message
news:[email protected]...
> On Mon, 19 Jan 2004 03:18:04 GMT, "Jim, N2VX" <[email protected]> wrote:
>
> >On Sun, 18 Jan 2004 23:11:41 GMT, Michael Hathaway <[email protected]> wrote:
> >
> >>Today, in a race, something happened to "shut down" the cadence function. The 720i stopped
> >>displaying cadence/power after that point, while HR, speed and clock continued to perform .
> >>After the race, I dis-assembled the caence magnet from the crank, and tried "flashing" it by the
> >>power strip (on the chainstay), and I am not getting any reading. Is it possible to either a)
> >>break the magnet, or b) break the cadence part only of the power strip? (I don't know the actual
> >>name of the "power strip" part on the chainstay).
> >>
> >>Any other ideas/suggestions would be greatly appreciated. Otherwise, it is off to the bikestore
> >>to try to replace the cadence magnet, hoping to solve the problem.
> >>
> >>Thanks, Mike Hathaway
> >
> >How strong is the magnet? I've seen some that are marginal. Replacing with a chunk of rare earth
> >magnet helped.
> >
> >Jim
>
> Well, I bought a new magnet (though not a super powerful one). I tested that it would trigger the
> light on the power strip (it did), and I attached it to the crank arm. It registered on the power
> strip AND on the 720i monitor - for a minute or so. After a minute, it stopped registering. I
> tried to move it around (thinking it had slipped/moved), but it no longer registered. After taking
> it off the crank arm, I tried it and the original magnet, but neither of them will even trigger
> the light on the power strip.
>
> Question: is it possible to have a broken cadence reader in the power strip? (the speed meter -
> magnet on the wheel still works and registers.) I am bummed because all of my trainer and road
> workouts are power-based.
>
> Thanks to anyone who can help, Mike

 

[Michael Hathawa]

Thanks for the clarification. What I meant to say is that I first noticed the cadence function not
working based on 00 reading on the 720i. And without cadence, power is also 00. That is my biggest
frustration as all of my workouts (rollers and road) are based on power ranges. Arrrggggh! After
getting the 00 reading for cadence, and being unable to modify the magnet on the crankarm to get a
reading, I ran a simple check: does the magnet even trip the LED anymore? The answer to that was no.
So then I bought the new magnet, got an LED reading, got on the rollers and began riding. After
about 30 seconds, the 720i again stopped showing the cadence/power.

<one note: in the original malfunction, it had been working correctly for about 5 months, several
times a week, including hard rides and races. the malfunction occurred during the final sprint at a
criterium on Sunday>.

So, since the speed function continues to work, and the LED flases red from the wheel (but no longer
green from the cadence), I have determined it is broken and am returning it to the retailer
(Performance said they would take it since it is only 6 months old and seems to be defective). I
have also ordered a replacement - I just hope it gets here soon.

Thanks again for all the help and insight. Oh well....

Mike

On Thu, 22 Jan 2004 11:07:44 GMT, "Per Elmsäter" <[email protected]> wrote:

>Per Elmsäter wrote:
>> Michael Hathaway wrote:
>>> Well, I bought a new magnet (though not a super powerful one). I tested that it would trigger
>>> the light on the power strip (it did), and I attached it to the crank arm. It registered on the
>>> power strip AND on the 720i monitor - for a minute or so. After a minute, it stopped
>>> registering. I tried to move it around (thinking it had slipped/moved), but it no longer
>>> registered. After taking it off the crank arm, I tried it and the original magnet, but neither
>>> of them will even trigger the light on the power strip.
>>>
>>> Question: is it possible to have a broken cadence reader in the power strip? (the speed meter -
>>> magnet on the wheel still works and registers.) I am bummed because all of my trainer and road
>>> workouts are power-based.
>>>
>>> Thanks to anyone who can help, Mike
>>
>> Are you sure it wasn't just the LED quit flashing after a minute or so? I just mounted the
>> original LED a couple of days ago from my new
>
>I meant of course to say that I mounted the original magnet, not LED.
>
>> Polar Power package and I have no problems. Even though the magnet is almost 10 mm away from the
>> sensor. It didn't work until I mounted it on the top of the crankarm. I had it on the botom at
>> first and that did not work. What you have to be aware of is that the LEDs will only blink for
>> the first 50 revolutions of your crank or wheel. After that the LEDs go out, but you will of
>> course be able to monitor your cadence and speed on your S720i display. You will have to
>> completely stop pedaling and rolling your tire for a minute or more before the LEDs once again
>> will signal activity.
>>
>> BTW do you ever see a yellow LED blinking indicating that the chainspeed sensor is active? I see
>> a red and green LED but no yellow. However the red LED blinks in places where the magnet on the
>> wheel is not active. This makes me suspect that there is no yellow LED, but two red and a
>> green???