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Polar power puzzle
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I must have jinxed myself with a thread last month about my problem-free installation of a Polar power meter. It has now gone flaky on me. I have lots of clues about what must be wrong, but I can't put it all together. Can anyone help me solve this mystery?

On my last outdoor ride, the cadence & power output disappeared for the last hour of the ride. But I did NOT lose the speed reading. I'm pretty sure that means all the connections must be good.

I thought perhaps the cadence magnet was out of position (and that the power reading depends on cadence). But I get green LED flashes when the crank arm passes the pickup, so the sensor is definitely registering the cadence, but the signal doesn't make it to the display on the bars.

On a trainer ride today, the cadence & power came back, but intermittently. Under effort, I'd get cadence and power readings, but when Coach Troy told me to soft pedal, I'd lose them both. I still had a speed signal the whole time.

Last clue: even when I had power, the power numbers were crazy. They registered at 700 - 1200 W, when they should have been reading 150 - 300 W. After seeing this, I tried repositioning the chain speed sensor, but that didn't seem to change the power readings. I also tried moving the big "cigar" sensor around a little, with no luck.

I'm stymied. Can anyone tell me which component is likely to have gone bonkers? And whether it's any use to try reinstalling / repositioning, or should I go straight to Polar?
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Re: Polar power puzzle [sjstuart] [ In reply to ]
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Could be a couple of things
1) the surfboard has been knocked out of position (I sometimes get this when loading/unloading the bike from the car). It often doesn't take much to get is misallinged if its not zip-tied very tightly, this normally manifests itself by only getting power readings in certain gears. In this case you should get cadence readings unless you have moved the surfboard too far from the cadence magnet (doesn't seem to be your problem though)

2) the wire to the chainspeed sensor is loose/broken, this isn't always obvious - the cable can look intact, but wiggling it can cause it to make/break the connection. I managed to break mine when fixing a flat - I'm afraid its back to Polar to get it fixed if this is the problem. When this was the problem I wouldn't get the light on the surfboard registering the chainspeed sensor (i.e. it would only flash for cadence and speed). The watch will only display/record speed/distance (not cadence or power).

I think your problem sounds more like the 2nd one, but its worth double checking the alignment of the surfboard just in case.

My sensor was out of warranty, so it cost me £15 (around $30) to get it fixed and checked by Polar in the UK, turnaround time was pretty quick at 3days.
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Re: Polar power puzzle [doug_steel] [ In reply to ]
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Thanks, doug. I actually have NEVER gotten a light (amber?) for the chainspeed sensor, even when everything was working fine. I only get green cadence and red speed flashes. I guess that's another clue.
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Re: Polar power puzzle [sjstuart] [ In reply to ]
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sjstuart

I hope this suggestion is not a insult because of the obvious! But.... Have you changed the battery in the watch cradle? When I had mine, I had to change it frequently.

DB
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Re: Polar power puzzle [Dbeitel] [ In reply to ]
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Definitely not too obvious -- I had to go check to make sure the watch cradle actually had a battery. I'll try that just in case, but I doubt that's it. I've only got ~150 miles with the power meter on the bike. Although maybe the battery was old when I got it, who knows.
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Re: Polar power puzzle [Dbeitel] [ In reply to ]
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I changed the battery, just in case, and that appears to have fixed it. So thanks for the advice!

Next question: do I really have the change the battery that often? According to my log, I have been on the bike about 11 hours since I installed the powermeter. You say you had to change yours "frequently" -- how frequently?
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Re: Polar power puzzle [sjstuart] [ In reply to ]
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You'll need to replace it fairly regularly, maybe every 4 months or so just to be sure. The major problems are:

No reading at all
- cadence sensor out of line
- power unit out of line
- watch not aligned on battery compartment
- battery totally dead
- connector pin slightly out of line
Weird readings
- battery dying
- speed sensor not close enough
- chain speed sensor not close enough to chain
- connector pin slightly out of line

Hope that helps

Xav

AeroCoach UK
http://www.aero-coach.co.uk
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Re: Polar power puzzle [sjstuart] [ In reply to ]
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I've had to change mine once in three years. Which is about as often as I can deal with shopping at Radio Shack, the only place that carries the battery locally.
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Re: Polar power puzzle [sjstuart] [ In reply to ]
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Before you go all crazy check and make sure the watch is seated properly on the pins and that the pins that connect tot he back of the watch are not corroded.
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Re: Polar power puzzle [sjstuart] [ In reply to ]
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I'm glad that seemed to help it. I just remembered that when I had mine, when it started to act flakey, I changed the battery first.

The other posters have some good suggestions, but it might been as simple as the battery that you put in not having a full charge!

DB
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