Polar S720i and Power Output Sensor

[Per ElmsäTer]

I know that Power sensors have been discussed and I have taken part of the different comparisons
between Polar, SRM etc. However since I do happen to own a Polar S720i HRM already it seems
logical for me to choose the Polar Power Output Sensor. I know that it isn't 100% but neither are
the others.

What I'd like to know is if those of you that have been using the Polar option for some time are
satisfied with what you've got or not? I'll be happy as long as it's consistent. If it's 300W or
350W in reality doesn't matter to me as long as it's the same readout every time.

Do the pedaling index really work? Ie does it help in producing an even roundpedaling motion?

--
Perre

You have to be smarter than a robot to reply.

 

[Andy Coggan]

"Per Elmsäter" <[email protected]> wrote in message
news:[email protected]...
> I know that Power sensors have been discussed and I have taken part of
the
> different comparisons between Polar, SRM etc. However since I do happen to own a Polar S720i HRM
> already it seems logical for me to choose the Polar Power Output Sensor. I know that it isn't 100%
> but neither are the others.
>
> What I'd like to know is if those of you that have been using the Polar option for some time are
> satisfied with what you've got or not? I'll be happy as long as it's consistent. If it's 300W or
> 350W in reality doesn't matter to me as long as it's the same readout every time.
>
> Do the pedaling index really work? Ie does it help in producing an even roundpedaling motion?

Since you've already got the heart rate monitor (and assuming you've only use one bike), then the
Polar may be a reasonable option. I would just make sure that it is giving consistent power numbers
in all gears (the Polar's major limitation, apparently). That can sometimes, but not always, be
achieved by making sure that the chain is very, very close to (even sometimes touching) the sensor
at all times (not possible on all bikes/with all gearing combinations).

Note that the Polar doesn't work well, if at all, on a trainer.

I don't recall if you're a member of the wattage list or not, but if not you might ask for
additional opinions there: www.topica.com/lists/wattage/read

Andy Coggan

 

[Per Elmsäter]

Andy Coggan wrote:
> "Per Elmsäter" <[email protected]> wrote in message
> news:[email protected]...
>> I know that Power sensors have been discussed and I have taken part of the different comparisons
>> between Polar, SRM etc. However since I do happen to own a Polar S720i HRM already it seems
>> logical for me to choose the Polar Power Output Sensor. I know that it isn't 100% but neither are
>> the others.
>>
>> What I'd like to know is if those of you that have been using the Polar option for some time are
>> satisfied with what you've got or not? I'll be happy as long as it's consistent. If it's 300W or
>> 350W in reality doesn't matter to me as long as it's the same readout every time.
>>
>> Do the pedaling index really work? Ie does it help in producing an even roundpedaling motion?
>
> Since you've already got the heart rate monitor (and assuming you've only use one bike), then the
> Polar may be a reasonable option. I would just make sure that it is giving consistent power
> numbers in all gears (the Polar's major limitation, apparently). That can sometimes, but not
> always, be achieved by making sure that the chain is very, very close to (even sometimes touching)
> the sensor at all times (not possible on all bikes/with all gearing combinations).
>
> Note that the Polar doesn't work well, if at all, on a trainer.
>
> I don't recall if you're a member of the wattage list or not, but if not you might ask for
> additional opinions there: www.topica.com/lists/wattage/read
>
> Andy Coggan

Thanks. I will go check out this list, didn't know about it at all. What do you mean that it doesn't
work out on a Trainer? I see nothing different on the trainer than on the road. As far as I
understand it will be easier on the trainer to keep the chain consistent by not changing gears as
much and instead changing the resistance on my trainer. I have the Tacx Swing trainer.

--
Perre

You have to be smarter than a robot to reply.

 

[Per Elmsäter]

Andy Coggan wrote:
> I don't recall if you're a member of the wattage list or not, but if not you might ask for
> additional opinions there: www.topica.com/lists/wattage/read
>
> Andy Coggan

I am a member now and have started to plow through the list, starting with the FAQ. Thanks for
letting me on to more info than I'll ever be able to swallow

--
Perre

You have to be smarter than a robot to reply.

 

[Jens Kurt Heyck]

> Thanks. I will go check out this list, didn't know about it at all. What do you mean that it
> doesn't work out on a Trainer? I see nothing different on the trainer than on the road. As far as
> I understand it will
be
> easier on the trainer to keep the chain consistent by not changing gears
as
> much and instead changing the resistance on my trainer. I have the Tacx Swing trainer.
>

Strictly speaking, it doesn't work on *many* trainers. This is probably due to vibration from the
resistance unit and tire (the Polar uses chain vibration and tension to measure power). The Polar
readings on my Tacx Imagic didn't appear too bad. Of course, it's pretty clear the Imagic power
readings are off to begin with, so it's hard to say for certain how well the Polar was doing.

Also, the chain need not touch the sensor, unless you're running a really big gear range and using
the extreme combos. I used it on my 52-42-30 triple with 12-25 and got reliable readings on all
reasonable gear combinations without it touching.

Anyhow, you can talk all that I say with a grain of salt since I'm selling mine. I got a Powertap
wheel and gave my brother my s710, so I haven't any use for the power unit anymore.

-- Jens

 

[Robert Chung]

Per Elmsäter wrote:
> Andy Coggan wrote:
>>
>> Note that the Polar doesn't work well, if at all, on a trainer.
>>
> What do you mean that it doesn't work out on a Trainer? I see nothing different on the trainer
> than on the road.

He means this: http://mywebpage.netscape.com/rechung/wattage/testing/testprotocol.html

Installation hints can be found here:
http://mywebpage.netscape.com/rechung/wattage/installation/s710photos.html

 

[Per ElmsäTer]

Robert Chung wrote:
> Per Elmsäter wrote:
>> Andy Coggan wrote:
>>>
>>> Note that the Polar doesn't work well, if at all, on a trainer.
>>>
>> What do you mean that it doesn't work out on a Trainer? I see nothing different on the trainer
>> than on the road.
>
> He means this: http://mywebpage.netscape.com/rechung/wattage/testing/testprotocol.html
>
> Installation hints can be found here:
> http://mywebpage.netscape.com/rechung/wattage/installation/s710photos.html

Thanks. Lots of interesting reading.

--
Perre

You have to be smarter than a robot to reply.

 

[peterwright]

Originally posted by Per ElmsäTer
Robert Chung wrote:
> Per Elmsäter wrote:
>> Andy Coggan wrote:
>>>
>>> Note that the Polar doesn't work well, if at all, on a trainer.
>>>
>> What do you mean that it doesn't work out on a Trainer? I see nothing different on the trainer
>> than on the road.
>
> He means this: http://mywebpage.netscape.com/rechung/wattage/testing/testprotocol.html
>
> Installation hints can be found here:
> http://mywebpage.netscape.com/rechung/wattage/installation/s710photos.html

Thanks. Lots of interesting reading.

--
Perre

You have to be smarter than a robot to reply.

I have just changed from the Polar unit to an Ergomo and would urge you to look at other options before buying the Polar. It does seem like a good deal if you already have the HR monitor but...

It is very hard to install to get consistent readings and I also found that about one in four rides I would find something not working due to a sensor that i had knocked or dislodged.

It is impractical and inconsistent and at best a compromise.

Why not look at an ergomo and get a reliable and harder wearing device that is more accurate and easier to use.

Good luck

Peter

 

[Robert Chung]

peterwright wrote:
>
> Why not look at an ergomo and get a reliable and harder wearing device that is more accurate and
> easier to use.

http://mywebpage.netscape.com/rechung/wattage/ergomo/ergomo-pt.html