funny you ask, I was reading this blog the other day. The author is a San Diego based coach and exercise physiologist

http://www.crankcycling.com/...-this-is-ridiculous/

This seems like a gimmic to me. Not saying thay HR and power are not correlated normally but as most know our HR varies as a result of a multitude of other factors. Sure maybe in a normal situation on a normal day our HR will correlate to X power but what about on the abnormal day...ie. race day. We are a little anxious, a little nervous, is the correlation still the same? I doubt it. If you are going to use HR to "guess" your power then why not just use HR.

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Supported by Compressport Canada | F2C Nutrition | Element | Argon 18 | 4iiii Innovations | Read my Blog

That was my impression. Still hoping for a review from someone who has used both.

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maybe she's born with it, maybe it's chlorine
If you're injured and need some sympathy, PM me and I'm very happy to write back.
disclaimer: PhD not MD

It's not bad actually. Been using it on and off.

In steady state riding - it's really darn precise. Within a few percent in my experiance. In surges, or drills - it tends to be off (initially for surges). Drills are tough because if you're doing for example one-legged or high cadence, the driver for that is more aerobic than leg power. But honestly, that's fine. The author of that article doesn't appear to grasp who the market of this device is for.

And honestly, it's not for most on ST.

It's for people like my dad. He loves to go out, ride, maybe do a few century rides a year, and just enjoy time on the bike. He's not about to lay down $800+ for power meter. But he's curious. His riding doesn't include drills, nor too many random surges. So for that price, it gives him a rough order of magnitude on his power.

Having been to the CycleOps product launch about it - their goal isn't to be 100% accurate. Thier goal is to be within a few percent. And based on my testing thus far, it does that. I'll be posting a full in depth review, but I've been spending less time on the bike the past month so I didn't have all the time to get all the rides that I wanted with it.

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My tiny little slice of the internets: dcrainmaker.com

So, how about for winter usage for a girl who is not good on the bike but can run and swim. I'd be using it on the trainer to do intervals. If a PM is a perfect 10 for that, what would you rate this, 1-10, for that use? Can you compare that use to just a HRM (same, better)?

Thanks :-) I appreciate your feedback and time. I'd love to read your review when it's written.

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maybe she's born with it, maybe it's chlorine
If you're injured and need some sympathy, PM me and I'm very happy to write back.
disclaimer: PhD not MD

Depends on the length of the intervals. Assuming more than 30-45 seconds - then it'll do fairly well in my experiance. If you're doing 30x30's, not as much (at least initially). It'll give you a road order of magnitude.

Now, depending on your trainer - check out TrainerRoad, they can do Virtual Power as well, worth a shot and probably a bit more accurate (since it's mostly simple math).

As for a scale #, I'd put it at a 7 in your case. It's not perfect, but not failing either. It gives you a rough order of magnitude. Just ensure as you improve you continue to recalibrate (Read: Find a friend with a PM or CT).

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My tiny little slice of the internets: dcrainmaker.com

The little ad for it on cycleops web site claims it needs to be calibrated against a powertap hub. If that's the case, how is it useful for people who don't want to own a powertap hub? (or am I not interpreting the ad correctly).

You can calibrate it against any ANT+ enabled hub. I calibrated mine against a Cinqo (all I had).

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My tiny little slice of the internets: dcrainmaker.com

Actually, to clarify, you need a Joule head unit - the actual PM doesn't matter. I'd have to think if I can import a non-Joule file into PowerAgent and base it on that (which is where you can do calibration). Don't have it handy at the moment.

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My tiny little slice of the internets: dcrainmaker.com

OK, good to know. So you need a friend with a PM to get the Cyclops Thing up and off the ground.

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maybe she's born with it, maybe it's chlorine
If you're injured and need some sympathy, PM me and I'm very happy to write back.
disclaimer: PhD not MD

Sounds like it would depend on the type of intervals.

Just to give you an idea of the type of variability you can expect between HR and power, here are plots (at one-second intervals) for the same guy in three different types of races.

Ooooh, scatterplots! Thanks. Me likey.

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maybe she's born with it, maybe it's chlorine
If you're injured and need some sympathy, PM me and I'm very happy to write back.
disclaimer: PhD not MD

It's not that hard getting something that's close on average -- what's hard is figuring out the conditions when it's not, and when the average isn't good enough.

Just to give you a bit more context, here's a different rider in a road race. First, the raw HR and power data (HR in red, using right hand scale):



It's obvious that there is *some* relationship between HR and power but it's very, very noisy. Here's a first cut (i.e., not what I'd do if I were really interested in modeling the HR-power relationship but it'll give you an idea of the degree of difficulty), which is smoothing the raw data over 60 second spans:



Better, eh? Still, even at 60-second smoothing, what's the correlation?



That correlation coeff means that the R^2 is still < 70%.

Now, this is, of course, a naive model of an inherently bursty power demand so it's likely that if the demand were closer to steady-state the fit would be better. How much better is the issue. As I said, it's not how close you can get on average -- it's knowing the conditions when it's not.

I thought Dede Demet had a restraining order on you using her data ;-)

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http://bikeblather.blogspot.com/

The term is "courting," thank you. The restraining order says "no-no," but her eyes say "yes-yes."

 
I have a feeling the word she would use is "stalking"... ;-)

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http://bikeblather.blogspot.com/

Tigerchick,
Did you check out TrainerRoad.com yet? If you are planning on trainer based interval rides for the winter, it may be just what you are after.

I am not affiliated, just a happy customer.

I think some of the saris guys are on here.....maybe they will chime in. I am definitely excited about a $250 power meter even if it's more of a guide than a provider of hard data. Seems like plenty of info to be useful for many of us. I'd think it would be better than training/racing with no data if its used properly. There are still some folks that manage to pace themselves and train effectively without power meters out there though ;)

I'm liking this for 60-90min spin classes at the gym over the Winter, when I'm not on a PT-enabled bike or Computrainer. At present, I'm just using TRIMPS, and might do better.

I'm confused. How is this better than a heart rate meter? Could I not just go through a calibration process and learn that at 150bpm im probably putting something that once evened out should be about 150 watts, and 200 watts at say 170bpm???

Am I missing the point here.

why are you anti-business?

I second the suggestion for trainerroad.com. Really cool program and really cheap at 10 bucks a month.

That looks the most feasible if I get a Garmin HR monitor and the ANT+ usb device.
When you use it in HR mode does it tell you power output?

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maybe she's born with it, maybe it's chlorine
If you're injured and need some sympathy, PM me and I'm very happy to write back.
disclaimer: PhD not MD

If you have certain trainers it will do Virtual Power. There's a bit thread here on it, and the guys behind it (Nate and Reid) will happily answer questions all day long.

As far as Power Cal guys, I've still gotta write something up - but the market largely isn't folks on ST, but rather our friends and family that just want a rough order of magnitude for $150. For that, based on my tests, it does pretty well. I wouldn't use it to pace an Ironman by power, but if you're out there doing a few hour rides for fun, it's interesting (and generally, based on what I've seen - for most conditions, fairly accurate).

Conditions it slacks in: Drills, high cadence, some low cadence, very short power surges/sprints (less than enough time to get your HR up significantly). For lower sprints/surges it tends to do better.

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My tiny little slice of the internets: dcrainmaker.com

I have a really old mag trainer that probably isn't compatible with anything.

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maybe she's born with it, maybe it's chlorine
If you're injured and need some sympathy, PM me and I'm very happy to write back.
disclaimer: PhD not MD

If you go on their website, they have a list of trainers that the program is compatible with. THe list is on this page http://www.trainerroad.com/virtual-power. You can't do it without a speed and cadence sensor on your bike. You don't need to have any sort of computer such as a garmin forerunner or anything like that, instead, all of the data goes from the sensor to the usb stick to the program on the computer.

Which trainer? Sometimes the manufacturers publish the curves. Other times we've had people ride them with power meters to develop them.

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CEO at TrainerRoad
Co-host of the Ask a Cycling Coach Podcast

Hi Nate,

I am impressed; you may have it.


My trainer says "Minoura Mag 500." There's no /850LW .

I'll send you a PM...

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maybe she's born with it, maybe it's chlorine
If you're injured and need some sympathy, PM me and I'm very happy to write back.
disclaimer: PhD not MD

A little more detail on the calibration here http://www.youtube.com/watch?v=5RHw0YzOQZk Supposedly it will be at distributors 20Jan to ship.

From your comments, it sounds like it WOULD be better over a longer period of time - like pacing an IM. I am small and found that my power meter yielded very little help over what I would have from HR. I know that HR trails power, but I am also interested in the power cal. Will wait for more info from you.

Yes and no.

My concern with an IM pacing on it, is that your HR will slowly erode, especially the last 30-40 miles - meaning you may be impacting your HR to power ratio beyond what the test will predict.

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My tiny little slice of the internets: dcrainmaker.com

Are you sure? I think it actually would be very useful for people who use a power meter regularly because it should allow them to correlate cross training workouts to their bike workouts.

For example, my PowerTap is laced to a carbon aero hoop. I'm not using it on the road now that the pavement in the northeast is cratered from freeze-thaw. Rather than buy another PowerTap training wheel, I'm thinking I can use the PowerCal to easily gauge my winter rides against my summer rides (+/- 5% which is fine for this purpose). Or when it snows and I go X/C skiing instead of riding, I can use the power conversion to pace myself to simulate a bike workout. And if I decide to take a spin class with my friends, rather than a spin in the freezing cold, I can still ride with power feedback. But I would still have my PowerTap on the trainer at home for cross-checking the calibration.

Naturally it is going to be useless for pacing rapid intervals--at best it will tell you what you did wrong on the last one. And it's not going to be good for pacing deep into an endurance event because of heart rate drift. Plus it's rather pricey for a heart rate strap with a programmable calibration table. But we're paying for the development and the convenience of being able to get power equivalent where we don't have access to a power meter. Now that I have been using a PowerTap for training and pacing, I've calibrated my thinking in Watts. So I think the PowerCal would let me expand this framework beyond the bike.

Has anyone had a chance to try any of these applications on the PowerCal yet?

Those are indeed valid secondary uses - and one of the reasons I think it's a cool product. But, I would say that for many on ST, as a primary product (first power meter), I think most will align with a direct force power meter (DFPM), like you have.

Enjoy!

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My tiny little slice of the internets: dcrainmaker.com

Just like the original poster, I've been looking for a powermeter, just happened upon the powercal product and done what little reading is available.

The issue I would see being a problem is the need to re-calibrate every 4-8 weeks, meaning regular access to a Joule computer!.

That aside, can't seem to find if the product has actually been released yet, regular searching doesn't bring up any suppliers.

Anyone know where I can check one out?

TIA

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Glen

That is not accurate information, although that was what I had been told by Saris/Cycleops. The fact is they dumbed down the product. Cut the price in half, $139.99 for the deluxe model. And turned out an absolute worthless piece of junk!!! I have 4 Powertap wheels and 2 Computrainers so I am very accustom to training with power. I wanted the PowerCal for CX and Mtb. Absolutely pure junk! The power/watt readings I get are typically 100 to 150 watts BELOW the effort! And it is not real time; it is an average. I have been coasting at 450 watts and then, while doing an effort, be riding at 40 watts!
Do not waste your money! I am trying to return this junk!

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Russell DeBarbieris

Apparently not necessary now. It's inherent (in)accuracy is not bettered by regular calibration;

Quote:

Why does it no longer have to be calibrated?
After years of research and reevaluation of the algorithm it was determined that the calibration process added no more accuracy than the algorithm alone. Due to the variability of heart rate, both between and among individuals, calibration did not statistically increase accuracy of translated energy expenditure. Some individuals may see improved accuracy through calibration but, as a whole, the results show the algorithm alone is able to translate heart rate to power as well as individual calibration.

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Trust me I’m a doctor!
Well, I have a PhD :-)

I'm playing with it and will do a full post later. Short version is you can't use it to manage an active workout (intervals) but it seems like it might be useful to track summary power and fitness over time.

Good for things like when you are on a borrowed bike, can't afford a real power meter, or maybe even spinning/crappy hotel gym bikes.

Does anyone know if this algorithm is similar to what Strava uses to determine power?

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AirlineBagFees.com/bicycles
Going on a bike trip? Find out what it costs flying with a bike on the airlines.

No, it is not. Strava uses grade & speed to gauge power... on flats Strava's power estimate can be extremely inaccurate due to wind speed.

This device uses heart rate variation (the change in heart rate, rate and magnitude) to determine power.

What I don't get:

if there is not calibration anymore, how can it have any idea of your basic zone ?

I red all the Faq and nothing about it (http://www.cycleops.com/...qs/powercal-faq.html)

for example: Lance is probably @200W when cursing @100bpm, on my side I will be more @100w for the same HR...

So how can it be accurate at all ? Ok if you were coupling it with GPS data and Speed it may have a better idea (as for Strava), but with only HR I don't get it...

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Head coach and owner at BartCoaching.com

This was our initial concern as well and why we assumed a calibration would be needed.

However, in testing that assumption in the lab it was pretty clear the calibration did not provide a significant improvement across our intended customer base.


We concede the product won't work for Lance. We've set it up for a reasonably fit athlete knowing that the established issues with using heart rate to determine energy expenditure are bigger limiters for PowerCal than the absolute power to heart rate relationship of a given individual relative to another.


Hope this helps-

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Jesse Bartholomew

Thanks for your answer Jesse, I was referring as Armstrong as an extreme to emphases on my argument, but the same can be apply between an average Age Grouper and an AG qualifying for Kona. (or even easier: between boys and girls)


Here is a screenshot from my first test...

Using a PowerTap, with the yellow computer, and the PowerCal with my Garmin 910XT.

I've been out for a recovery ride.

I took several Split while cursing.

Here is a comparison from the same split (ignore de start time, as I started the YellowComputer later)

On the left is the PowerCal value, on the Right is the PowerTap.


You will notice a huge difference between the two value.

Ok, we know there is no more calibration, so I can still live with the idea that there is an offset that I need to add between my real Power and the PowerCal value.

Next step: I will be testing on Treshold Intervals, to see if there is an offset or any logical relation that make this tool more useful than just a cardio belt.

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Head coach and owner at BartCoaching.com

Is your "cruising" heart rate really < 125bpm? That's really low and outside the normal range assumed in the PowerCal algorithm, which roughly speaking would assume a bpm of 140 to 150 for an all day type pace.

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Jesse Bartholomew

140-150 will be more my HIM pace, between 145 and 160 I will be around FTP -10 to 20mn intervals-, around 325w.

I'm quite sure any good AG will be below 120 bpm when cruising. (my easy ride are around 100bpm)

But I will test it during Tempon and FTP session, were Power information is more useful than when cruising.

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Head coach and owner at BartCoaching.com

Jesse, I sent you a PM.

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Head coach and owner at BartCoaching.com

Bump.

Any updates or more recent opinions on this?

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VDOT O2 Run Coaching
Team INFINIT Discount Code: RowanJones

This is why I never bought one of these. My threshold is around 310 watts, maybe a little more when I'm really fit. In any case, I think this watch is calibrated for the less serious bike rider that has a threshold closer to 220. Which means the watts would read low if I were to use it.

Had they added even a simple calibration screen that asked what your threshold power was, I think that would have helped.

I use it and tested it against what the compu trainer WATTS numbers where giving me and I was a good 25% BUT when you look at HR and WATTS it balances things out.

I still would like to add an *actual* power meter, but for $99 I bit. I just got it today and paired it up since I'll use it for HRM during my afternoon run. I did notice that there was a "Calibrate" in the PM menu on my 910XT. Is there anything to that or is it just a default drop down in the menu? I have a 1:30 trainer spin in the morning so I'll be interested to see what sort of numbers it comes up with (I have no idea about my FTP, etc. because I have never worked with power/a power calculator). So the 20 minute test is sort of the standard way to go to determine FTP?

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VDOT O2 Run Coaching
Team INFINIT Discount Code: RowanJones

Well, ideally a 40K TT would be the best test, or 1 hour riding as hard as you possibly can. Either of these would give you a good ballpark for your threshold. But only if you are using a real powermeter. Otherwise you are simply guessing. As I stated in my last post, if you are a relatively fast cyclist, the power will not show correctly on the PowerCal. It is calibrated for an average bike rider.

I see. I don't know where I stand as far as being +/- average (21.2 mph at my last HIM and still had good legs for the run), but if I understand that the actual numbers I'm looking at aren't 100% correct, couldn't I still use this as a way to track improvements and/or regulate efforts on long steady rides by way of comparison? So say this gives me a threshold of 250W, but it is truly and actually 275W if I were using a real power meter; I could still use that data to monitor effort and track improvements in fitness, no? I do understand that this thing is basically useless for interval training (well, that's what the internet told me anyway).

Who wants to sell me their used power meter?

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VDOT O2 Run Coaching
Team INFINIT Discount Code: RowanJones

Of course. Athletes were using just heart rate monitors for many years before powermeters came out. You just don't have as exacting of data your training. But it still works.

For many athletes, they do not train to their fullest potential on the bike anyway, so a dedicated regimented training routine using heart rate will still allow them to see large improvements.

I've been using a PowerCal for 4 months. Before I get into my impressions understand where I am coming from. I am a college student who can't afford a true PM but wanted something to more objectively compare my own efforts to those I have done previously.

First thing to note is that this isn't just a HR --> Power calculation. When I jump for a sprint my power hit 1100 to 1200 watts according to PowerCal. There is no more delay in the reading on my Garmin than I get from my speed sensor. Whereas I would simply see my HR start to increase on the HR graph. I've found that similar efforts in training match up very well. If I am in a road race though... all bets are off all the nervous moments send my HR skyrocketing and thus my power. I was nearly hit by a car once, my speed went down by my power hit 1600 watts. Yeah that didn't happen.

I am much better at pacing TT's since I got the device, I can set off from the go hitting targets instead of exploding early when the adrenaline is running and high effort levels feel easy. Did only 1 tri this year, but was able to do some awesomeness for it. I used my CP for estimated combined run and bike time to pace myself on both. Brought my Garmin with me on the run. Rode the 12th fastest split of the day (I'm 52kg so that's an accomplishment in and of itself), and ran 6:38 miles on the 5k afterwards (fastest run off the bike ever). A big part of this was that I held myself back early on both sections being able to see the "power" numbers.


I would never in my life ever compare these numbers to the power #'s of someone else though. According to my powercal I can push 5.3 w/kg for an hour, and 10 for 1 minute. Which is total BS. But I know I can use those numbers each time I'm out putting down my interval efforts. Works for what I need for now... although I'm hankering for a bit more and I'm sure an actual power meter is coming post christmas.

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Jordan Oroshiba --- Roadie invading Triathlete space for knowledge access

I might give it a shot

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Formely stef32

Great for zones once you figure them out (typical power curve relationship I have found, does not apply). Each of my zones is about 30 "watts" on the powercal. Numbers are also complete crap (My actual 5minute power is about 270w, powercal says 305w, FTP about 220 powercall gives me 280). That said I have been able to pace myself very effectively using it.

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Jordan Oroshiba --- Roadie invading Triathlete space for knowledge access