531Aussie

I just got an s725x as a gift.

Anyone know much about the power sensor kit?
Is it accurate?
It looks a bit cumbersome

badsac

Geez, someones sucking up to ya. Of course it's worth getting it. You'll get sick of it after a month and never use it. But still, gadgets are cool.

The_Convert

stay away!

531Aussie

have you got one?

OB1

I have one. Works great while on the road but forget the trainer; totally erractic. I've heard other report their's work fine on the trainer.

thebchessl

I heard it is not accurate or consistent from a friend who had one. He went to a Power Tap and has been happy.

shawneebiker

I've had one for about a month now. It was a bit fussy to set up. Had to replace the battery out of the box. Trainer watts don't seem to be really accurate. Road watts on average seem to be accurate. Forget about getting accurate watts on sprints due to the 5 second recording rate.

Now with that said........

My speed sensor just stopped working for whatever reason on the unit. I now have to hassel with Polar for warranty. I think once I get it back I'm going to sell both the 725 and power unit on ebay and opt. for the PT Pro SL. If you can get the power option for cheap then give it a try. I wish I would have cut my losses sooner and gone with the PT Pro SL.

I think the 725 is great without the power option. I love the data. I just wish the power option was better.

ks1g

Only 3rd-hand experience (reviews and comments on bikeforums); the physics behind the polar power sensor are sound, but the implementation is more complicated and finicky to install than for the Power Tap system or crank-based power measurement. OTOH, the additional cost is the least since you already have the HRM.

I'd ride with just the HRM for a while and see if you think you are really missing anything by not having a power measurement. I have a 720 and while I wouldn't object to someone giving me the power sensor , and as an engineer, I love number-producing gadgets. However, I'm not even close to feeling limited by "only" having current and average HR, speed, cadence, altitude, temps, and lap splits and averages recorded during a ride. I'd rather spend the money on more useful gear for me or the bike at this point.

If you have your heart set on knowing how much power you can produce, find a place that provides calibrated power measurement. There's a cycling/tri training shop near here where I had a LTHR/VO2max test performed for $150 that properly set my training zones, gave me practical advice on improving my riding, and gave me calibrated data that is much better than anything I could capture on my own.

uga8589

I have a 725X and a 725. My wife bought me the 725x and the power output sensor for Christmas. I love the 725 and the 725x, they are both great. I just don't think I need the information from the power sensor. I never used the power sensor. If you know anyone that wants both, I have the 725X and the power sensor on the FOR TRADE thread. It's been long enough now that my wife won't even miss them.

badsac

Nup. But I paid extra for the cadence sensor for my 720 used it for a ride, got bored with it and never used it again. I'd imagine this would be similar. Although with you being ultra serious in training up to beat the nobs down beach rd, it might come in handy.

I went to a seminar on training at the recent cycling expo in sydney. The dude doing the talking had trained a lot of our sprinters (can't remember his name) and he rekons a power meter is essential for getting the most out of your training.

BTW, he said the polar power meters did a decent job and were worth it.

mloywhite

I have had a 725 for awhile, and last week added the power unit. I read a lot about installing it before I got it, so I had no problems with getting it running. It is very consistent on the road, on the trainer it has a high reading (50 watts in one, 25 in the next, then normal again) when I am in two adjacent gears on the back, but otherwise is consistent inside. I ran it at the same speed for a minute in each gear, on the trainer, and repeated a 2 minute hill climb in each gear, (not very steep) at 13 mph outside, then compared the watts it showed for each, to see if they fluctuated. Outside it looks very consistent.

You might check out:
https://www.u.arizona.edu/~sandiway/bike/s710/index.html

https://www.schererfamily.com/Joisey_.../polars710.htm

https://www.midweekclub.com/powerFAQ.htm#Q8

The top two are mostly about set-up the last has a very good compare/contrast of power units including the polar one

also see: https://mywebpage.netscape.com/rechung/wattage/ Their site can be slow, but it is worth the wait

How accurate is it? I don't know. I got a good deal on mine, and decided to give it try. If it keeps consistent readings, and I can workout with it, I will be happy with it. So far so good, I will see over time. There are websites that can give you the actual wattage needed based on weight, etc. so you can compare what your meter says to what it should actually be, to help with checking the accuracy, I have not tried that yet.

531Aussie

thanks for the replies, and thanks very much mloy for the links

merlinextraligh

Unless you're going to set up a training program based upon power, you don't. But if you want an effective training program, the power data will definitely help you design and implement a program that will get the most return for your effort. Whether the Polar unit is accurate enough to really use in a power based training program appears open to debate. For me, I found going to the the Power Tap SL for $250 more was worth it.

DrWJODonnell

What do you want to achieve? If you are looking to step into the realm of power training, Polar is an inexpensive way to do it (considering you already have the watch). Having multiple bikes, I have two power units, one watch which s about the same price as seting up one bike with the slightly more accurate SRM.

One person said that it is no good for sprints. This is true. However if set up properly (which is not really hard to do) the polar is dead accurate over the average ride or even interval longer than 30 seconds. I have had no issues with it on my trainer. I would have considered Powertap but they do not make it for disc wheels and TTing is one f the places where I woud like to have power visible during the ride. I cannot comment on ergomo's unit.

Bottom line. If you are into serious training with power and not using it for the curiosity factor go for it (I like that the polar also records altitiude which the other power units do not ??you can correct me on that guys). If you are not sure about power training, or are not a racer at all, then just wait and see if you even enjoy heart rate training first. If you have unlimited cash, then go for the SRM setup. If you have specific questions email me.

531Aussie

thanks, Doc

I'm not really sure how I'd like to use the power meter, but I'm definitely curious to see what sort of wattage I'm generating during time-trial type workouts and intervals.

I've had heart rate monitors since I bought my Polar Edge in 1992, so I've been checking that out for quite a while, so I know my HR limits, etc, very well

I've just got back to racing infrequently (about once every 3 weeks), and trying to get my fat guts (6ft, 200lbs) out of criterium corners has made me realize that I'm kidding myself thinking I'm serious at this weight. I'm disciplined enough to do the miles (averaged approx 11,000 to 12,000 miles in the last few years -- 13,051 was my best), but it's the rest, stretching and eating where I suffer

Anyway, I'm 38, and I wanna do some damage on the local scene, particularly with time-trialing, before I get too old,

531Aussie

CRIKEY!!!! The sensor kit retails down here for $723 AUS ($520 US)!!!!!

https://www.cecilwalker.com.au/category20_1.htm

I don't think I'll be getting one

I could buy another frame for that

DrPete 

It does, however, beat the $3400 ($4700 AUS) SRM Dura-Ace Crank....

I'm still in the ranks of those weekend warriors not serious enough to train with power...

DrPete

531Aussie

yeah, rediculous!! How long's it gunna be before good power meters are affordable?!