Introducing PowerCal a new kind of Power Meter

[dracs]

And yet the reviews (i.e actual data) out there indicate that it gives better data than heart rate alone and much better data than an online estimator like Strava. It doesn't give the same accuracy as a true direct force PM (nor does it claim to), but then it doesn't cost R9000+ either.

 

It's a reasonable compromise between cost and accuracy. I am seriously considering one as a load (i.e. TSS) estimator for MTBing, rather than shelling out R12,000 for another direct force PM.

exactly. I don't know the voodoo it uses but it works

I think its bull if you know how your heart works then it has nothing to do with power. Just go read joe friel's heart rate training bible, Your heart is unique individual and works differently every day. And depending on a million of factors like illness, fatigue, food, etc the rates changes, I am no doctor but from the bit i know and have read Im damn sure theres no way to get an acurate power reading from your heartrate. Other factors are the delay in HRM's as they dont poll often enough, the time it takes for your heart rate to get up to tempo after prolonged excessive length the curve goes down. Which means your heart rate starts dipping even though maintaining the same speeds/effort.

 

And the only reason you have power meters is because they are more accurate than heart rate monitors for training. Even if the formula comes close its still not acurate and wont help you in the slightest besides having "interesting" data. Sort of like the way strava works out your "power" output based on heart rate.

it doesn't use heart rate but heart rate variability. Just anectdotally when riding with the thing if I freewheel after a really hard effort with my hear rate still at say 160, or freewheel after low effort with heart rate at say 120, the bloody think registeres 0 or close to zero watts....

 

Intuitively I agree it should not work - but it does to (to a certain level of accuracy anyway)

Edited November 30, 2012 by dracs

[covie]

exactly. I don't know the voodoo it uses but it works

it doesn't use heart rate but heart rate variability. Just anectdotally when riding with the thing if I freewheel after a really hard effort with my hear rate still at say 160, or freewheel after low effort with heart rate at say 120, the bloody think registeres 0 or close to zero watts....

 

Intuitively I agree it should not work - but it does to (to a certain level of accuracy anyway)

 

Go read a couple of books on power training, what makes power effective is its extreme accuracy and the fact that you can change your training thanks to the accurate data given by a power meter. Hence why i said this would give you "interesting data" but as far as a proper training mechanism its not on par.

 

I would'nt mind semi acurate data for interest sake but i would prefer acurate data for training.

[dracs]

 

Go read a couple of books on power training, what makes power effective is its extreme accuracy and the fact that you can change your training thanks to the accurate data given by a power meter. Hence why i said this would give you "interesting data" but as far as a proper training mechanism its not on par.

 

I would'nt mind semi acurate data for interest sake but i would prefer acurate data for training.

sure it comes back to cost / benefit I suppose. Probably if you have used proper power data this won't cut it, but for a newbie like me its interesting

[SeaBee]

Agreed, plus it gives you input into more tools (play-thingies! ) from which at least you now get some form of TS values, etc. Even if just for guidance, I find it handy.

 

I do get the odd weird spike, but I think you even get that on full-blown PT's. And as dracs mentioned, I've also seen high HR values correctly yielding lower power values, orat low HR values it shows high power values long before HR pops up. More than "just interesting" to me.

 

No, I haven't yet tried it for full-blown power-based intervals, etc. Give me a break, I've hardly touched the roadbike! But may very well see what gives in those terms during Dec.

[FrancoisO]

(play-thingies! ), think it would still be more accurate for calculating TSS, than guessing from your heart rate.

[Jeepdude Bertus]

So all you hubbers who bought the PowerCal, how is it working for you?

i was so excited tostart using it... and have been very succesfully and pretty close to other powermeters.... then i hit a snagg. i have started using blood pressure meds , went through quite a few variants in a very short time... the longest of which i was on a beta blocker , which effectively made the Powercal useless as a PM , the beta blocker keeps your heart rate low... so i was doing 4 hour rides at 120-130 avg bpm heart rate , lucky i am off those now but it was pretty frustrating

[Blackadder]

Jeepdude - how did the beta blocker impact your power output readings on Powercal? Assuming your heart rate is 25 odd bpm lower than normal, was the power output consistently lower than your output before you took the betablocker? Or did it fluctuate wildly, which would indeed render the Powercal useless.

 

I ask as I am in the same boat.

Edited December 28, 2012 by Blackadder

[Jeepdude Bertus]

Jeepdude - how did the beta blocker impact your power output readings on Powercal? Assuming your heart rate is 25 odd bpm lower than normal, was the power output consistently lower than your output before you took the betablocker? Or did it fluctuate wildly, which would indeed render the Powercal useless.

 

I ask as I am in the same boat.

POWER was just WAAAAAYYYYYY down , i guess you can carry on with the lower numbers , but you dont have a true reflection on power numbers. i do suggest going off the beta blocker and finding an alternative. i was using the beta blocker during preparation for the double century and it had a very undesirable affect.. i did hours of riding but lost speed and ability to rev the engine so to speak...

[NotSoBigBen]

Does the 'absolute' number matter or is it how you use/interpret that number?

[Dr Snuggles]

Does the 'absolute' number matter or is it how you use/interpret that number?

 

if the outputs are inaccurate, but stable, then the relative change between those values are of more importance than the actual number itself. Plotted over a period of time, it will give you a fairly good indication of changes in your performance. but if the instantaneous value is inaccurate, and if there are large variations in output under the same conditions, then it's practically useless tbh. But I dont think the latter is the case with this type of powermeter simply because the algorithms that determine power from the one parameter it picks up is constant. That parameter being your HR.

So I would suggest you look at relative changes in power readings over a period of time to determine your level of performance.

[Blackadder]

 

 

if the outputs are inaccurate, but stable, then the relative change between those values are of more importance than the actual number itself. Plotted over a period of time, it will give you a fairly good indication of changes in your performance. but if the instantaneous value is inaccurate, and if there are large variations in output under the same conditions, then it's practically useless tbh. But I dont think the latter is the case with this type of powermeter simply because the algorithms that determine power from the one parameter it picks up is constant. That parameter being your HR.

So I would suggest you look at relative changes in power readings over a period of time to determine your level of performance.

 

That is my understanding. What I would like to know is what the impact of a beta blocker that lowers hr has on the algorithm that calculates power with PowerCal. If PowerCal measures changes in hr rather than absolute hr, then the impact of a beta blocker on hr should be minimal. However, whilst I get stable and predictable power readings, like Jeepdude above, I find my power readings are rather low. Perhaps it's just my poor performance and I am looking for excuses????

[Dr Snuggles]

That is my understanding. What I would like to know is what the impact of a beta blocker that lowers hr has on the algorithm that calculates power with PowerCal. If PowerCal measures changes in hr rather than absolute hr, then the impact of a beta blocker on hr should be minimal. However, whilst I get stable and predictable power readings, like Jeepdude above, I find my power readings are rather low. Perhaps it's just my poor performance and I am looking for excuses

 

If one looks at what beta-blockers actually do, and i quote from wikipedia:

 

Beta blockers target the beta receptor. Beta receptors are found on cells of the heart muscles, smooth muscles, airways, arteries, kidneys, and other tissues that are part of the sympathetic nervous system and lead to stress responses, especially when they are stimulated by epinephrine (adrenaline). Beta blockers interfere with the binding to the receptor of epinephrine and other stress hormones, and weaken the effects of stress hormones.

 

IMO:

Training is physical stress, and is reacted upon as a normal stress response by your body, and therefore, you are going to underperform according to PowerCal at the same level of exertion. If you dosage is constant, then like with inaccuracies, the relative difference between performances at the same level of exertion under the same dosage will be what's important. Absolute values are skewed because of the effect of the beta-blockers. But one must keep in mind that when under the influence of any drug, there is a peak period followed by a taper as the drug follows its degrading impact curve. One could use drug-half life as an interval during which one assumes constant impact. In reality, it tapers off as the renal system filters it out of the blood stream, and even that varies due to changes in physiology brought about by physical activity. But i'd make an assumptions of constant dose over an interval based on drug half life.

 

Knowing these periods of constant dose, one can then make better assessments of PowerCal data on a relative basis. Absolute values should be discarded IMO.

[raptor]

Were can i buy a powercal? Waiting 3 days already to hear from bicyclepower

[NISI]

Were can i buy a powercal? Waiting 3 days already to hear from bicyclepower

Maybe they only open Monday after the festive season-only good service from them.I waited 3 days to reciev my powercal

[Wallee]

Were can i buy a powercal? Waiting 3 days already to hear from bicyclepower

 

Have you tried online? www.bicyclepower.co.za

[BicyclePower]

Were can i buy a powercal? Waiting 3 days already to hear from bicyclepower

 

sorry to hear you have been waiting so long, to the best of my knowledge we have responded to all queries via e mail.

 

drop an e mail to dave(at)bicyclepower.co.za