I have been using the s710 for HR, cadence and altitude all of which have worked well. I am thinking about springing for the extra 350.00 and getting the power attachment. Is it worth it? Or should I save my money for a powertap? Any issues I should be aware of?
thanks…
Works great, takes a bit of time to put on. Buy on ebay–pick one up for < $200.00.
I had a Powertap & I like this just as much, if not more as it doesn’t STB like my PT was wont to.
I picked one up in Performance Bike’s “40% off room.” Don’t know if I’d pay full price for one.
Yup it’s a biatch to get dialed in. chain weight, chain link count, and a bunch of other numbers you need measure or calculate.
I did a LT test a few months back on a computrainer and was able to see how accurate the Powermeter was. It was consistenly 45-50 watts off the computratiner’s display as Chris, guy running the test, pushed up the wattage.
So I think in order to verify my numbers I’m going to have to bring my oily bike chain to a deli and ask them to weight it.
If you can find one on Ebay it’s probably the cheapest way to introduce power/wattage training into your program.
I only use it in off-season as watch needs to be mounted to bike in order to speed,cadance anlong with power reading to work. So it ain’t condusive to racing with if you want to see your speed and have to be taking your watch on and off in transistions or whilst riding.
Jim
Triman,
I stepped up to an SRM, and have my Polar power unit for sale. It worked satisfactorily even with low installation effort. The software makes pretty graphs too. 
All parts present in good working order. I even have tie straps to replace the ones I used. $175 shipped from Denver.
Joe
I have used the Polar Power device for a month or so now and I am only half satisfied with it. The thing is that the measurement seem to be dependent of either distance between the sensor and the chain or horizontal position of the chain, i.e.where the chain is on the cassette. I tend to get too high readings in the 19-25 rings compared to the 12-17 rings at the same speed. The deviation can be 20% or more. I use a 1-up trainer and compared to the power chart for the trainer, the output in the small rings match OK and the big rings are quite a bit off. Riding on the indoor trainer I can control the gears ratios and make sure my intervals are at the correct wattage, but this will not work as well at comparing outdoor sessions.
I believe that I have set it up correctly, but it may help if I move the sensor along the chain stay.
I did not use the generic 304g weight of my Ultegra chain, but deducted the weight of the piece I chopped off. I’m not sure if this is correct.
Has anyone else the same experience with the Power device?
Sindre