Polar S-710 and power sensor

[JøRn Dahl-Stamn]

Anybody using it? Would like to hear about experiences with it.

Jørn Dahl-Stamnes, EDB Teamco AS e-mail: [email protected] (remove nospam first)
web: http://spiderman.novit.no/dahls/

 

[Andy Coggan]

You might wish to visit www.topica.com/lists/wattage/read. (In general, peoples' experiences with
the S710 haven't been great.)

Andy Coggan

"Jørn Dahl-Stamnes" <[email protected]> wrote in message
news:[email protected]...
> Anybody using it? Would like to hear about experiences with it.
>
> Jørn Dahl-Stamnes, EDB Teamco AS e-mail: [email protected] (remove nospam first)
> web: http://spiderman.novit.no/dahls/

 

[Jens Kurt Heyck]

I've got one. Installation was a bit of a nuisance. Since I installed it, I seem to have a
high-level of chain noise that I can't seem to eliminate. Haven't figured that one out yet.

Other than that, I'm pretty happy with it. I have some reason to doubt its accuracy, as it always
gives me different readings than the computrainer. See the following website for Sandiway Fong's
analysis of this issue:

http://external.nj.nec.com/homepages/sandiway/bike/feather/tt/s710/index.htm l

Although the accuracy probably ain't perfect, it seems like one of the easier ways to measure power.
I've found it to be a pretty useful training tool for evaluating the effectiveness of riding
position, etc.

-- Jens

"Jørn Dahl-Stamnes" <[email protected]> wrote in message
news:[email protected]...
> Anybody using it? Would like to hear about experiences with it.
>
> Jørn Dahl-Stamnes, EDB Teamco AS e-mail: [email protected] (remove nospam first)
> web: http://spiderman.novit.no/dahls/

 

[Bbc3]

"Andy Coggan" wrote:
> You might wish to visit www.topica.com/lists/wattage/read. (In general, peoples' experiences with
> the S710 haven't been great.)

I have been using the S710 for almost a year now and I have been very pleased with it. I added the
power sensor last month and it works quite well -- no complaints. The software that comes with the
Polar is great.

Interesting comparison:

Polar S710 vs. Power Tap vs. SRM http://www.monkeyhillcs.com/chung/rosetta/rosetta.html

Overall the SRM and the Powertap are probably more accurate at reading individual power spikes, but
the Polar seems to turn out very reliable data.

--
Bill

 

[Robert Chung]

"BBC3" <[email protected]> wrote
> "Andy Coggan" wrote:
> > You might wish to visit www.topica.com/lists/wattage/read. (In general, peoples' experiences
> > with the S710 haven't been great.)
>
> I have been using the S710 for almost a year now and I have been very pleased with it. I added the
> power sensor last month and it works quite well -- no complaints. The software that comes with the
> Polar is great.
>
> Interesting comparison:
>
> Polar S710 vs. Power Tap vs. SRM http://www.monkeyhillcs.com/chung/rosetta/rosetta.html
>
> Overall the SRM and the Powertap are probably more accurate at reading individual power spikes,
> but the Polar seems to turn out very reliable
data.

The Polar appears more sensitive to the way it's installed than the other two: a good installation
appears to produce reliable data but a poorly-installed unit definitely does not. One of the
problems is that the LEDs might light up even if the installation is poor, so without testing you
don't know which situation applies. See:

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

This is not meant as a slam on the S710. The SRM and Power Tap also have their, um, idiosyncracies.

 

[Andy Coggan]

> "BBC3" <[email protected]> wrote
> > "Andy Coggan" wrote:
> > > You might wish to visit www.topica.com/lists/wattage/read. (In
general,
> > > peoples' experiences with the S710 haven't been great.)
> >
> > I have been using the S710 for almost a year now and I have been very pleased with it. I added
> > the power sensor last month and it works quite well -- no complaints. The software that comes
> > with the Polar is great.
> >
> > Interesting comparison:
> >
> > Polar S710 vs. Power Tap vs. SRM http://www.monkeyhillcs.com/chung/rosetta/rosetta.html
> >
> > Overall the SRM and the Powertap are probably more accurate at reading individual power spikes,
> > but the Polar seems to turn out very reliable
> data.

Yeah, now if only every S710 sold came with custom installation by one of the co-inventors,
everything might work okay (except on a trainer or rollers). ;-)

(BTW, note that there may be reasons to question the accuracy of the SRM Amateur crank used in that
comparison.)

Andy Coggan

 

[Robert Chung]

"Andy Coggan" <[email protected]> wrote
> Yeah, now if only every S710 sold came with custom installation by one of the co-inventors,
> everything might work okay (except on a trainer or rollers). ;-)

The S710 certainly seems to have a higher fiddle-with-it coefficient than the Power Tap or the SRM.

> (BTW, note that there may be reasons to question the accuracy of the SRM Amateur crank used in
> that comparison.)

Have you heard anything specific, or is this an allusion to what we've already discussed?

 

[Andy Coggan]

"Robert Chung" <[email protected]> wrote in message
news:[email protected]...
>
> "Andy Coggan" <[email protected]> wrote

> > (BTW, note that there may be reasons to question the accuracy of the SRM Amateur crank used in
> > that comparison.)
>
> Have you heard anything specific, or is this an allusion to what we've already discussed?

It is pure speculation, based upon:

1) the approximate age of the SRM crank in question;
2) the fact that Adam hasn't calibrated it;
3) the fact that it is an Amateur model; and
4) the fact that at some time points the SRM and PowerTap agreed very closely, but at other times
they didn't. Whether that is due to power losses in the drive train, errors in the SRM data due
to off-axis torques, or merely reflects random error, I don't know (although the answer might be
in the data), but I find it bothersome.

In any case, my point is merely that a single three-way comparison is hardly proof of anything, yet
people often cite this example as the final word on the subject.

Andy Coggan

 

[Robert Chung]

"Andy Coggan" wrote
> (BTW, note that there may be reasons to question the accuracy of the SRM Amateur crank used in
> that comparison.)

and

> It is pure speculation, based upon:

[snip]

Possible, though I think that even if the SRM wasn't accurate, it certainly seems that its accuracy
couldn't be horrific. Some of the difference between the SRM and PT is surely due to the different
ways they got to 2-second and
2.52-second reporting intervals.

> In any case, my point is merely that a single three-way comparison is
hardly
> proof of anything, yet people often cite this example as the final word on the subject.

I'm sure it doesn't surprise you that I agree. I think of it as far closer to the first word on the
subject than the final one, and that's why whenever I notice people pointing at the three-way
analysis I point at the aberrant readings analysis. I think good statistical analysis doesn't
provide answers as much as it makes you think of new questions. (That analysis makes me think of
lots of new questions so it must be pretty good).