Deals + Steals - Forum Archive

May 25, 2013 at 07:49 PM

Figure I'd weigh in here as another that has been using the PowerCal all season. Yacks and I have been experimenting with it and sharing notes. Unlike him, I don't have a computrainer or other means of determining if my powercal readings are close to accurate. As an absolute measurement of power it may or may not be accurate, it is likely luck with a +/-5% margin. For me it is a guesstimate based on my physiology. I suspect it is overstating my power by 20-30 watts for any given time period of 5 mins or more. However, it is very consistent, which for purposes of training serves me reasonably well. I've effectively never trained with power so take everything I saw with a grain of salt.

The last couple of weeks I've been using it to train within specific power and HR zones and I set up the garmin that way. For a 5 min VO2max effort or a 20min LT effort I can simply watch the zone numbers and measure my effort that way. While I've been focusing on the HR zone more, the Pwr zones seem to work reasonably well too and could be used as a guide during a training ride for the interval. To be clear, I'm not watching a power number in watts - it is simply saying I'm in zone 4 (4.2, 4.5 etc) which is based on the standard Hunter Allen power zones as a percentage of FTP. I might with more experience be able to dial in where I want to be even further e.g. 4.7 rather than 4.2.

The other great thing about it is I can download the data and it'll compute TSS/Bikescore for the ride and I can track my training load in Golden Cheetah's performance manager chart. (WKO, training peaks, Strava all have an equivalent). I use the PM chart along with the power curve chart to see if I hit the top part of the curve for the zone/period I was aiming for (5min, 20 min, 1hr etc) - note I don't bother with anything less than 5min as I don't think it is that accurate for shorter periods and for those short periods I think I can get to where I need to be based on RPE and HR.

Here are the downsides - I have no idea what my FTP is, what my true 20min power is etc. I don't know how many watts/kg I can put out. So I can't compare my engine with yours. (mine is a 3.5 hp Briggs & Stratton lawnmower engine and yours is a 3.0 liter 310hp supercharged Audi engine). The biggest down side is I can't see improvements in power / fitness. This point isn't the most intuitive so I'll explain. The power figures are based off of the rate of change of my HR and the HR during an effort. If my HR goes from 160 to 170 in the same span of time, the powercal doesn't know if that change is during my first week of training in March or in the middle of May when I am actually reasonably fit. To the algorithm in the powercal it looks like my effort and change in power are the same. I realized this after watching my power curve in Cheetah for weeks and my CP curve didn't move despite my knowing that I'm getting fitter. Other objective measures like my 5 and 20 min efforts show that I'm stronger since I'm going further at higher average speeds for the same period of time given similar conditions on the same road. It is effectively a measure of my effort level, rather than my power level.

So here (in DCrainmaker fashion) are some pros and cons:

Pros:

+ inexpensive - effectively $30 more than a standard ant+ HR strap (~$80 on sale online)

+ effectively tracks training load and allows for the use of standard analysis software

+ can be used to pace longer efforts (=>5min) by power zone or HR zone

+ post ride analysis of power curve peaks for specific efforts =>5mins effective

+ portable - take it on vacation and rent a bike, use a spin bike, etc and you can still record (with Garmin or other head unit) workout for import into software when you get home

Cons

- not a true measure of power - can't join in on the bragging that I did 420 NP for 2 hours (mine has never come close. My best one hour power is 264 according to the powercal and I think that is over stated)

- doesn't measure/capture improvements in power output over time

- can't use to pace short efforts

- given limitations, it may not work for coaches that want to look at power files (I haven't asked but have thought about this a bit lately)

Happy to answer any questions. I still long for a true power meter and may still get one but I'll see what I can and can't do with this for a while longer before dropping some more cash on a quarq or stages pm.

edit: I wanted to throw in the quote "it never gets easier, you just go faster" somewhere in there but didn't. The quote fits since for the same level of effort I will go faster since that effort level will produce more power as I get fitter.

Adam

Jun 03, 2013 at 06:32 PM

So, with the Powercal thing.

I wanted a Powermeter for only one of my workouts. That is the hour TT that I do, inside on a stationary trainer. What I do is go by HR at present. The thing that is a little frustrating is that if you hit the same HR all season, there is no measure of if you are actually going faster or not. Would this be identical for the Powercal then, seeing as it too is simply measuring HR and re-badging it with a transformation?

Craig Zolan

Jun 03, 2013 at 07:00 PM

@Adam - based on my experience you'd have the same problem with the powercal as you do with HR alone for your trainer TT sessions. There are two online companies that can give you a power curve for specific trainers and then you can convert your time and speed on the trainer into power figures. I've heard these are relatively accurate. That would allow you to measure your progress on the trainer over time. I can't remember the name of the companies off the top of my head but can find them if you want.

Marc Bertucco

Jun 03, 2013 at 07:02 PM

Adam, I'm going to let Yaks answer your question most directly, because he's got that Powercal knowledge inside and out...

But, you can also consider going a little more old school with your training/measurement. If for example you log in a "Perceived Rate of Exertion," along with distance from an old-school cycling computer with a rear magnet/mount, and you set up the trainer the same way, the tire at the same pressure, the weather/temp conditions roughly the same. Then, even without heart rate, you will have at least a fair sense of what kind of improvement you might have had over the year.

Craig Zolan

Jun 03, 2013 at 07:54 PM

here are a couple of the powercurve companies:

http://www.trainerroad.com/
(DC rainmaker's review http://www.dcrainmaker.com/2011/09/inside-look-at-trainerroad-way-to-make.html)

http://www.peripedal.com/ (just stumbled upon this one now)

Adam

Jun 03, 2013 at 07:57 PM

Craig-thanks for the response. I was hoping for a cheap/quick power answer but it seems that the reason that you pay so much for a meter is that it's not that easy. I will stick with the HR monitor then.

Marc-Good suggestion and those are the things I have been doing. I even make a note of the room temperature as my Garmin calls it, trying to keep as many variables constant. I think that is how it's going to be unless I am willing to spend the money to get a real meter. For those interested, I have attached some of the graphs that I have on my data.

A couple of things. My obsessive number crunching exposes my scientist-ness. Second, I do a 15 minute warmup followed by a full gas, 50 minute TT. The Garmin HR graph (this corresponds to the TT on 15 May BTW) shows what I look like throughout. Notice the 4 'dips' in my speed throughout the session, that's when I have to stand up for 10 seconds to allow the blood to flow back into my crotch! I don't do the full 60 minute TT as the whole thing like this is 65 minutes and is absolutely killer. At the end, when I do this exercise properly,you couldn't pay me $10,000 to do another 10 minutes! At the end I spin for 5 minutes.

The bars (left hand side Y axis) show my average HR. The line (right hand side Y axis) shows my average cadence. This basically shows you the variability in my approach. I pump up the rear tyre to the same 120 psi with the same pump, use the same bike and the trainer should be set the same. Same gear ratio. It's hard to draw a lot of conclusions for the data as is. Before racing season, I do this once per week. As you can see, the more training I did, the worse it got in terms of the HR I sustained (I would force the issue even if I knew that day wan't going to be spectacular). It's great training even if you can't do a 'full gas' effort. I do the exercise less as I get outside do more and more interval-type stuff and race. It's hard to do this for real as you need a good rest before the day and after. The last one, on 15 May, was after a very long training block and after a rest period. I felt great at the time. It was the highest HR I hit all year (185-my highest I had in 2012 was 186), but according to the cadence (97) would have "moved me less distance" than the considerably weaker effort (HR 174) on January 15th (cadence 99). This is simply the variation with this method I feel.

In short, HR is very subjective. What felt 'horrible' in some sessions was easy in others. Hence, the interest in a more objective power measurement.

HR.png

HR_15_May.png

Jules

Jun 04, 2013 at 12:15 AM

@Adam, you've got enough bikes - fork over for a power meter and be done with it, already, eh

(I hear Craig L is selling a nice one cheap)

As for variations in HR; they are so subjective based on hydration caffeine, temperature, etc... it's is damn hard to compare. If anything I'd ditch HR and just see how far you can go. You definitely have the intensity right.

As a bit of reference; I rode my first Power Tap for like years and years until it needed servicing - and then it cost a couple of hundred bucks to get it back in working order. Thousands and thousands of miles. It's still on Lisa's bike, happy to measure as ever. These things LAST.

twoyacks

Jun 04, 2013 at 01:06 AM

buy this ONLY if you are ready to take your performance to the next level...

PowerCal.jpg

Marc Bertucco

Jun 04, 2013 at 01:17 PM

Adam, you know, just based on your post alone, I have a feeling you are a precision-oriented guy. If you can afford it, I would think you would be happier with a strain-gauge-based power meter.

(also, I personally think that doing a full on 50 minute TT effort every week, even during the off season, is too much.)

Adam Fabian

Jun 04, 2013 at 01:33 PM

I'm beginning to think Yacks is a paid spokesman for PowerCal.

Jules

Jun 04, 2013 at 03:24 PM

Marc Bertucco said:

Adam, you know, just based on your post alone, I have a feeling you are a precision-oriented guy. If you can afford it, I would think you would be happier with a strain-gauge-based power meter.

(also, I personally think that doing a full on 50 minute TT effort every week, even during the off season, is too much.)

I don't know about that Marc. If someone can handle it (ie: doesn't burn out mentally) then fine - I mean we're all aiming to accumulate much more than 50 minutes a week of threshold.

What do coaches Ragot & PBerg think?

Adam

Jun 04, 2013 at 03:40 PM

Marc-I have sort of penned in buying a power in the coming off season. I'm generally looking into options at the moment, hence the interest in 80 dollar "semi" power meters. I think that the evidence out there is all simply pointing to a strain-based option. Will see. Now we don't have Cyclops on board there's no real easy choise.

About the TT being too much. As it's an indoor trainer session, which was pretty much 70% of my riding January/February because of weather (I refuse to go out below 32 deg.F), it actually split up the horrendous nature of indoor intervals throughout the week. Nice to mix it up if you are on the trainer 4 days per week. But yes, if you look through my January data you can see the efforts get worse. It's not possible to go max out for this exercise every week, like I said, to do it properly, you need a real rest both before and after. However, Even doing an hour or so at ~90% threshold I think is a great way to train. I swear by that exercise though, I am feeling the benefits of that 'base' training at this point of the year.

Ryan J

Jun 04, 2013 at 03:53 PM

Adam Fabian said:

I'm beginning to think Yacks is a paid spokesman for PowerCal.

If so they need to work on their messaging ... as someone who trains for bike racing on his bicycle I'm not sold by marketing speak such as:

"u can't really use it on the bike" and/or "power readings on the bike are useless with the power cal."

Adam Fabian

Jun 04, 2013 at 04:22 PM

Ryan J said:

Adam Fabian said:

I'm beginning to think Yacks is a paid spokesman for PowerCal.

If so they need to work on their messaging ... as someone who trains for bike racing on his bicycle I'm not sold by marketing speak such as:

"u can't really use it on the bike" and/or "power readings on the bike are useless with the power cal."

I never said he was good at it.

twoyacks

Jun 04, 2013 at 06:03 PM

Ryan the Powercal data is good when you download it....true you can not hold a power # on the bike as the power #'s fluctuate wildly. This goes for riding indoors as well. If you have a trainer that measures watts, you are covered. I had a power tap and I could never really focus on holding power numbers as I needed to watch the road...perhaps the Google glasses will solve this dilemma some day? The Powercal will not tell you your sprint wattage either as it under reports this # pretty dramatically. What is does do is give you information on how hard you worked. This information can help guide your recovery. I would rather have a power cal than a power tap because I have 3 sets of wheels and I use them all. Indoor training wheels, outside training wheels and race wheels. A crank based meter would be ideal...but I'm not dropping $1200 + on one of those.

Adam your remarks are emotionally charged. May I suggest less emotive language and more equivocal language? My messaging is not good compared to what? How accurate is any power meter in relation to another? Test a powetap against a Quarq against a Computrainer against a Powercal. You can run all four at the same time and all four will give you different #'s. My powercal has been consistent when performing the same workouts in a controlled environment (my computrainer). My philosophy of training orbits around these words, "If it hurts...it works". Heart rate and cadence are all you need to get really fit. We are all at different levels of suck...our power #'s just make the word suck a bit less abstract.

Ryan J

Jun 04, 2013 at 06:31 PM

twoyacks said:

Adam your remarks are emotionally charged. May I suggest less emotive language and more equivocal language? My messaging is not good compared to what?

Yacks I think you're attributing to Adam my joke about your "messaging," made in response to Adam saying he was beginning to think you were a paid spokesman for PowerCal. I assure you I wrote that with no emotion other than humor, having gotten a kick out of the the idea that thing is useless on a bike. It was just a joke. Sorry if it came off wrong.

twoyacks

Jun 04, 2013 at 06:59 PM

My good man... I am taking an online TESOL (teaching English as a second language course) and I had the forum up and my course on a split screen at the same time so I thought it would be good sport to inject some of the jargon on my forum post. Come on guy "emotive & equivocal language"??? The only emotion I possess is humor FYI. But on a more serious note the powercal is the greatest invention since 2 ply toilet paper. (How's THAT for marketing ?!) Take that Don Draper ! The only way you could improve the powercal would be to make it out of....waiiiitttt for it....Ti.

ian ellis

Jun 04, 2013 at 09:45 PM

Deals ... or not as the case may be.

I've used Wiggle many times, always selected the free - I don't care how long it takes - shipping option, and it usually gets delivered fairly promptly by USPS.

However my last order arrived even more speedily courtesy of DHL .... and hot on the heels of that an outrageous invoice for customs charges. 12%. TWELVE. that is 3 whole percent more than NY sales tax.

(Of course I'll file this in my special 'open when hell freezes over' folder of bills alongside parking fines and medical co-pays.)

However it remains an outrage.

I awaiting a response from Wiggle on whether this is their new outrageous policy, and I'll revert when I know more.

Adam Fabian

Jun 05, 2013 at 01:30 AM

twoyacks said:

Ryan the Powercal data is good when you download it....true you can not hold a power # on the bike as the power #'s fluctuate wildly. This goes for riding indoors as well. If you have a trainer that measures watts, you are covered. I had a power tap and I could never really focus on holding power numbers as I needed to watch the road...perhaps the Google glasses will solve this dilemma some day? The Powercal will not tell you your sprint wattage either as it under reports this # pretty dramatically. What is does do is give you information on how hard you worked. This information can help guide your recovery. I would rather have a power cal than a power tap because I have 3 sets of wheels and I use them all. Indoor training wheels, outside training wheels and race wheels. A crank based meter would be ideal...but I'm not dropping $1200 + on one of those.

Adam your remarks are emotionally charged. May I suggest less emotive language and more equivocal language? My messaging is not good compared to what? How accurate is any power meter in relation to another? Test a powetap against a Quarq against a Computrainer against a Powercal. You can run all four at the same time and all four will give you different #'s. My powercal has been consistent when performing the same workouts in a controlled environment (my computrainer). My philosophy of training orbits around these words, "If it hurts...it works". Heart rate and cadence are all you need to get really fit. We are all at different levels of suck...our power #'s just make the word suck a bit less abstract.

Sorry Yacks -- I was just riffing on what Ryan said. I can't talk -- I've got the PowerCal too! (ETA: I actually got it at your recommendation.) I was just trying to make a funny. Sorry, dude!

Adam

Jun 11, 2013 at 02:10 PM

By the way, where I work is selling one of their minibuses.

2000 Dodge B3500, 15- passenger van.

Mileage app. 131200

Here's a picture of a simlar van.

http://www.motorauthority.com/photos/dodge_ram-wagon_1997#100183557

The starting bid is $650, it'll go for cheap. We have until 18th June to put in an offer.

Maybe Kissena should put in a bid, a team van would be awesome for us to get to races. Great club asset.

Board!! This is the time to step up and make this club legit. We can even get Kissena decals!

David Yang

Jun 11, 2013 at 02:21 PM

Speed holes, we definitely need speed holes.

Brendan Rigby

Jun 11, 2013 at 02:39 PM

lawyers of the club, unite! are we incorporated? who would be on the van's insurance? does it matter? can we distribute candy from the van?

dstokes

Jun 11, 2013 at 04:02 PM

Although this purchase might be manageable, I think the logistics of caring for a team van is way beyond the Board (insurance, parking, access). But its a nice idea.

Adam

Jun 11, 2013 at 04:16 PM

Expatiate please, David.

Jules

Jun 11, 2013 at 04:46 PM

But I'm sure maintenance on a 10+ year old van with 100k+ miles on it will be a breeze. What could possibly go wrong?

[spoiler]

Countdown to Ragot lamenting the loss of his old shop tools begins....

[spoiler]

twoyacks

Jun 11, 2013 at 05:22 PM

If this vans a rocking.......