Ritterview

There was a time when there had been some controversy over whether power measurement was helpful or not in training.

Was.

merlinextraligh

I don't get the power cal straps. IMHO, you might as well just train with heart Rate.

We used to tain with perceived effort. Which had its limitations.

Then we trained with HR to help overcome the problems with perceived effort.

Now we train with power to overcome the problems with HR.

Power Cal calculates power from HR. I don't see how going back to HR, and extrapolating does much to improve the problems with HR. Might just as well stay with a HR based progeam.

Carbonfiberboy 

Agreed. I think you may have misinterpreted my comment. The gadget in question is not a PM. I'm certainly not arguing that a PM isn't a good tool. Just not worth the money to me.

twocicle

PowerCal had not been mentioned in this thread so I looked into it a bit.

Whether or not any power data is of importance to one person or another, reading through the links provided has some quantifiable data and a good indication of what to expect for both pro and con.

The implementation of PowerCal does seem weird to me too, as my petite stoker can easily get her HR up in the 160/bpm but develops maybe half my wattage at that same HR (completely ignoring HR ranges, LT, age, gender, etc). How they expect this product to produce accurate results is just... weird. While PC is probably the cheapest way to add Ant+ power data, it may be otherwise a useless addtion.

merlinextraligh

The summary of my take on Look Polar Keo Power pedals:

Look Polar Keo Power Pedal Wrapup



So, after a two week trial, they're boxed up and going back.

I couldn't get them to work on any consistent basis. It's possible that something in mine is defective and could be fixed such as with a new transmitter. However, my total experience with the pedals is such that I don't want them even if they could be made to work.


1) the lack of Ant+, combined with antiquated head units from Polar are the biggest weakness. One huge problem is that it can only display instantaneous power, which limits it's utility for pacing intervals. The short memory is also a problem. If you use a one second record rate, and record other data fields (HR, GPS,) you're down to a couple of hours. Use a longer record rate and to my understanding you're compromising the power data, most notably normalized power.

2) the user interface of the head unit is antiquted. Everything about the head units is just antiquated, from a non intuitive menue decision tree, to a balky IR upload (as opposed to a micro usb port), difficult, and limited ability to customize displays, non integrated gps unit, hieroglyphics for displays instead of english. The power meter itself has to be turned on each use, and takes 10-15 seconds to synch, not a huge problem, but more of a PITA, than hopping on the bike and pedaling backwards 4 revolutions.

Basically, Cateye circa 1998, called and wants their operating system back.

3)Ease of setup and swapping. Other than the limited case of using these on a tandem (my purpose) the major proposed advantage for these is to be able to easily swap out pedals across bikes. It is a bit harder to install these pedals, than just installing regular pedals, given that you have to precisely allign the pedals, then plug in the transmitters, and zip tie them down. Having done it 3 times now, I'm getting pretty quick with it, but it's still slower and a bit more complicated than swapping a crank based power meter.

4) Durability. The portion of the transmitter that sticks in the pedal spindle, just doesn't seem very robust. There are 2 tiny grommets on each one that tend to come off when you unistall the transmitter, and their are small exposed electrical connections. I'd be concerned about their longevity if you were moving the pedals around regularly. At a minimum you'd be buying a lot of replacement grommets, and zip ties.

5) Reliability. My sample of 1 proved to be completely unreliable. The anecdotal evidence I've gathered, however, indicates I might not be alone. The Competitive Cyclist customer service rep told me that they sold a few, and had a number of negative reports. My CTS coach has only heard bad reports, and the only other consumer reports I've seen on the web are also negative.

6) Customer Service. Twice a Polar rep told me he wasn't familiar with the product, and someone would get back to me. Only after escalating things with the help of a poster here at BF, a Look rep, and a negative facebook post. did I get any actual attention from Polar, at which point the horse had left the barn.

7) Price. At $2500, it's very hard to justify this system, even working as intended against a Quarq, or a Power Tap.


Polar pretty much admits that their core competency is heart rate monitors for runners and swimmers, and that developing cycling products, particularly power for cyclists is an evolving process. They indicate that better head units, and low power bluetooth are in the pipeline.

My suggestion is that if you don't run away from this product entirely, that you at least wait for the bluetooth option, and some time for Polar to iron out bugs, and develop some institutional knowledge to provide customer support for the product.

twocicle

Hey, the Polar power talk reminded me... we have 2 Polar S710 watches + 1 Polar Power Kit (the chainstay/vibration pickup) no longer in use. The Power kit has all new wires as I had them redone a couple years ago, but never reinstalled it. This setup can be installed on a single or tandem, though due to wire lengths will reach only the stoker compartment. It includes the speed/cadence/power all in the wired config, with no wireless bike sensors required. The Polar Power Kit setup was rated fairly well, and especially for the cost.

The watches (monitors) and power kit tech are a bit dated but work well. If anyone is interested, PM me or email: twocicle AT g mail DOT com

Ritterview

Wow, that is an informative and credible review. DC Rainmaker, move over!

waynesulak

I read recently that Polar has recalled all the power units for a fix. Not sure of the timing but it seems consistent with this report.

djconnel

They tested lowest measured power of the six units tested by German magazine Triathlon.

Blog post here.

Now the magazine article was fatally flawed, since there is a distinct possibility the company making the trainer used as a power reference calibrates their power measurement to an SRM, which thus happened to "win" the test as "most accurate". So all you can really say is the different units used disagreed, you can't say which is most accurate. But that Polar was such an outlier doesn't suggest wonderful things for its accuracy.

Hermes

On a different but equally interesting subject using real time power and speed from ANT+ devices to generate aerodynamic drag coefficient is this technology at the Velo Sports Center indoor track in Carson, CA. My wife had a session using the technology and it is amazing and better in person than described in the article.

Individual power measurement would not be required for captain and stoker and an ANT+ power tap wheel will do the trick. All one has to do is ride constant speed and the system picks up power and speed and you ride around the track and provides real time aerodynamic drag. IMO, the amount of testing possible for different positions and equipment for a tandem team is significant.

merlinextraligh

Just skimmed the link, and it looks cool.

My understanding is you can do this yourself with an Ibike aero, and a power meter, maybe not with the same degree of precision.

Ritterview

Just starting or Saturday tandem ride, I noticed that a rider waiting at the light had an attachment to his Keo style pedals. That was a prototype Garmin Vector, and the rider is Clark Foy, one of the original founders of Metrigear, which Garmin acquired. He said it was one of 12 prototypes in the field, and that the Vector was soon to be in production (consistent with the late Summer release the Garmin CEO used in the conference call).




I said that the Vector is the only practical means for tandems to have power measurement, and he says that has been discussed, with speculation that the quantitative revelation about relative power output would would enliven conversation and relations between captains and stokers.

twocicle

On occassion during rides I've begun tapping into my stoker's Garmin Ant HR belt ID (we each have an Edge 800) just to see what she's actually doing back there. Sometimes her HR is way too high, sometimes low. Her perceived effort rarely matches her HR level %, and it is difficult for me to tell by feel how hard she is working. When we set out with a goal (easy, mid, hard), this seems to help herd the cats. Other feedback such as excessive panting or talk are two additional inputs I use to gauge her

I've speculated, knowing a competitor's ANT ID could be quite interesting in a race. You'd see when they were pegged or not. Our belts seem to work from ~80ft away, so there is a lot of stealthness available

Carbonfiberboy 

My stoker uses a cheap Polar HRM for her HR and, as navigator, also has the 800, which displays - my HR. She just matches hers to mine, the same or a few beats different, depending on what she thinks of our comparative states of recovery, feeding, and hydration. Our LTHRs are maybe 2 beats apart. I have a Bontrager Node 2.1 to get my information.

IME, over say a 5 minute or longer period, HR reflects output and therefore stress, regardless of RPE. We've both been using HRMs for about 15 years. There's lag between us of course when the grade changes or I cause an acceleration or deceleration, but that all evens out. And if I want an attack, I still have to call it. This setup cost us about $200 more than a single 800.

The Node is the only weak spot - it loses the Garmin wheel sensor signal frequently, but I have a Flight Deck for that information anyway. Worked OK on captain's bars, but the new mount on the aero bars is apparently 6" too far away. Wish I knew of a more sensitive receiver.

You still have that Polar power kit?

Ritterview

Our Node 1 having a loose grasp on the Garmin speed/cadence sensor ANT+ signal became a nuisance, such that we converted to my old Garmin 705 for the stoker.

I wonder if the Node 2 performs better in this regard?

waynesulak

I also tried a Node 1 and found it unrelaible. I liked the fact that it would use separate cadence and speed sensors rather than the combined unit. Finally gave up on it. Does anyone know of any other ANT head unit that will use separate speed and cadence sensors?

CaptainHaddock

I have found that by having our HRM's cross linked, and talking a lot allows us really figure out our perceived vs. measured output. However, I cannot wait until there is a truly good system which allows us to measure two outputs.

twocicle

Yes, we have a box full of Polar S-series parts... 2-710i watches, 1-like new power kit, oodles of speed & cadence sensors and a couple IR data transfer units in a pear tree. I really do need to setup my own eBay store.

merlinextraligh

Looking at another possibility for at least measurement of the captain's power on the tandem.

https://www.stagescycling.com/stagespower

According to the customer service people at Stages, it will go on a Shimano R601 crank. It would be turning backwards, becaue the off crank arm in this case would be the right not the left, but apparently that's not a problem.

I hadn't seriously considered the Stage's power meter before because of the early bad reviews. But it appears they've ironed out a lot of kinks. https://www.dcrainmaker.com/2013/06/s...ew-update.html

I'm thinking of giving it a try. I'd like to upgrade our FSA Gossamer cranks anyway, and the price of the Stages power meter itself is relatively cheap by power meter standards.

Ritterview

I was interested in that as well. The backwards crank is probably an easily fixed problem, but I'd figure that it would require talking to Stages, and the minute that tandem is mentioned, they'd probably say, "Oh", and not provide any help whatsoever (with a vision of the tiny sliver of tandems on the bicycle market share pie chart). So, if somebody else wants to go through that, that'd be great. I'd just get indignant at the lack of respect shown tandems, and fume.

The thing with the Garmin Vector and a tandem, is that it will be easily transferable to the half-bike, so is a power-meter two-fer.

merlinextraligh

Here's my email exchange with them:

Hey Bob,

Just got your voicemail. The interface between your existing crank and the power meter will work just fine even though you are running on the opposite side it will not make a difference as the power meter will still register a load.

Thanks!


Evan From: Bob Stewart [mailto:]
Sent: Tuesday, July 16, 2013 8:35 AM
To: Stages Cycling Admin
Subject: compatibility with Shimano R601

Will the Ultegra Stages power meter with a Shimano R601 crank? The R601 is an “ultegra level” crank for the captain on a tandem. My assumption is that it would physically fit.

The arm would end up going on the right, not the left side, with a conventional cross over tandem set up, so it would be running backward. Would that create a problem for the power meter reading accurately?

djconnel

[QUOTE=merlinextraligh;15857326]it appears they've ironed out a lot of kinks. [/url]


Indeed -- they now do a credible job of measuring power generated by the left leg. However, all the data I've seen suggests assuming this is also the right leg power represents a considerable error, well in excess of the 2% claimed accuracy. If measuring power to within, for example, 10% is good enough then Stages is a good option.

Here's a screen shot from the Polar power meter, showing a 56% power balance:



If the 56% is the left, I get 112%. If the 44% is the left, I get 88%. The correct number is 100%.

merlinextraligh

[QUOTE=djconnel;15875192]The latest DC Rainmaker review indicates that Stages has improved considerably.

As for the right/left leg imbalance, for me, my Quark data ( which splits the pedal stroke in half, giving you effectively seperate right left power) indicates that I'm typically less than 1% different side to side.

Also, as long as the data's repeatable, being skewed 1% high or low due to leg descrepancies isn't a significant problem for training.


BTW, my experience with the Polar power system was a disaster.

waynesulak

I have been thinking about the stages power meter. Since it measures stress on the crank arm between the pedal and the spider I don't see why it would not work for the stoker as well. The the measurement is made before the captain's power is entered into the mix. If she is soft pedaling then there is less stress on the crank arm regardless of how much or how little the captain is working. I suppose that if the stoker is applying negative pressure to the arm that would foul the data but assuming the stoker is putting out some positive power it could work.

merlinextraligh

It comes as the left arm of certain cranks. At least now they don't retrofit it. Using a two sided setup, it wouldn't work because the left arm for the stoker has the spider for the timing chain built in.