Does anyone have experience with the Polar S720i and the optional “Polar power system”? Talked to my lbs and they said they have had bad experience with the polar power system. Any info?
yup… +/- % of error is big versus powertap 1-2% SRM less than 1%
You can get it to work pretty well but the fiddle factor is high.
If you’d like to try it out I’d sell mine cheap!
same thing as Kevin said, works but more fussing with it. Pretty consistent though once you get it set up. I need to get mine together and sell it as well. Nothing wrong with it I just realized that although power is cool I don’t really care. HR, now that I’m addicted too.
It takes a good long time to get it set up correctly, then there is no way to calibrate it except to put another powermeter on the bike and compare the two or do a timed climb on a bike with a powermeter then do it with the Polar power. It also is only good for long measured efforts, like a flat course or for pacing on a five minute or longer climb due to the very long minimum update time - power is only updated once every five seconds. The one nice thing about it is that one can use whatever wheel or crank or bottom bracket one desires.
http://www.midweekclub.com/powerFAQ.htm
I’ve used Polar, SRM, and PowerTap. You save money on the front end when you buy Polar but you pay it all back in time spent on maintenance of the system. All of them are somewhat finicky in some way but Polar is head and shoulders above the others.
What are your goals for using a power meter? What’s your budget? Do you already have a Polar S720i?
You can probably get one for about half price on EBay if you just want to try it. SRM and PowerTaps go for roughly 70 to 90 % of retail on EBay for comparison.
I used it for almost a year (have a unit for sale, great condition, $390 including the s725 watch if interested) and it works well, I just gravitated toward Powertap with Rotor Cranks, and the SRM/Rotor Q-rings that I am testing
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Yah everything SWOO said!
I picked one up in Performance Bike’s outlet store for 40% off. Fast forward 3yrs later and I have a CT now. I was typically seeing a +/-40 watt difference from what PPM was telling me versus what CT was telling me. there are 3 or 4 factors that you can use to tweak numbers.
If you can find one cheap try it, if $$$ isn’t an issue I would say powertap or one of the other higher cost models out there that are proven to be more accurate with less tweaking.
knowing what I knwo about it now, I definately wouldn’t pay full price for it, find a discount or 2nd hand one if you already own a S7xx series HRM and want to add the functionality.
I don’t have the power option, but I do have a S720i with the speed and cadence sensors. I’m not inclined right now to add another component to the system, given how temperamental the other pieces are. Even with the signal jumpers set to the max, I rarely complete a ride with both speed and cadence sensors 100% operational. Lately, even the HR signal has been a little inconsistent - it seems like it is hard to find a spot for the watch where it can pick up all the signals at once.
If you haven’t already set both SPD and CAD sensors to HIGH, that is where to start. I’ve got my SPD sensor mounted on the back wheel and get a good reading whilst on aerobars. I’ll lose CAD when I’m out on the cowhorns but that’s it.
I haven’t noticed any significant decrease in battery life; I also change them every yr though.
HOW TO: carefully unscrew the sensor, slide the circuit card out, move jumper onto the two outer most pins, re-assemble.
Thanks. I did that already and, while it did help, it was only an incremental improvement - I’d say things went from working 60% of the time to 80% of the time or something along those lines. It’s definitely worth doing, though.
here’s a link to a detailed study comparing the different power meter out there:
http://biketechreview.com/archive/pm_review.htm
I ended up going with the SRM Pro and use the S720i for heart rate and altitude only; the installation of the Polar unit is a mess and takes a long time to get right; also if your chain tension varies your power readings are not comparable over time; not to mention if you crash there’s a lot to replace
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