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View Full Version : PowerTap PowerCal - experience/opinions?..


Pastashop
12-27-2014, 05:34 PM
http://www.powertap.com/collections/powercal/products/powercal-bluetooth-smart

... uses known correlations between speed, heart rate, and power output to spit out power output estimates based on measured heart rate and speed. The info I've seen online suggests that it's reasonably close to actual power produced.

Anyone have experience with this? Does it come with a speed/cadence sensor already, or is that a separate purchase? Any recommendations on whether to get the Ant+ or the BlueTooth model?

Bruce K
12-27-2014, 05:43 PM
Variations from hub or crank based power can be up to 15% in my experience but for situations where it's close enough it is s fairly cheap way to get a sense of what your are doing

You will need to buy a speed/cadence sensor to commute the information you are looking for

I still use mine when I'm on my cross bikes just as a way to make sure I don't overdo things

BK

Pastashop
12-27-2014, 06:37 PM
Is it able to account for improvements in efficiency over longer periods of time with training (i.e more power at a given heart rate), or does that not happen to an appreciable extent?

Bruce K
12-27-2014, 07:35 PM
You can use it to account for improvements in power/fitness etc

Just be aware that the numbers may be off overall

BK

kramnnim
12-27-2014, 09:38 PM
DC Rainmaker for anything like this.

http://www.dcrainmaker.com/2012/11/cycleops-powercal-in-depth-review.html

SpeedyChix
12-27-2014, 10:15 PM
His reviews are pretty spot on. I picked one up to see how it was, have used it on the mountain bike a bit. Probably one of the more challenging uses for it (as I'd expect CX to be as well). The unit reports better over more sustained efforts.

They have been sold with a mix of setups from just the strap, strap and speed/cadence .

Pastashop
12-28-2014, 12:31 AM
Thanks for the link to the review!

From the review and comments, it seems like they got rid of the requirement to calibrate, and the sensor now doesn't need any speed/cadence information whatsoever to spit out the "power" number. And it's able to do so for different people, so it seems like there's some sort of algorithm that's processing either the raw heart rate or some variation in the heart rate into power.

A simple "look-up" table of data or a curve fit presumably covers some range of target users...

https://www.cyclinganalytics.com/blog/2013/06/heart-rate-vs-power-chart

http://www.toppfysik.nu/wp-content/uploads/2012/01/The-relationship-between-heart-rate-and-power-output-during-road-cycling-competitions.pdf

but how wide of a range?.. And, of course, as fitness improves, the simple curve fit for heart rate vs. power won't work anymore:

http://www.joefrielsblog.com/2011/05/speed-power-heart-rate-and-fitness.html

... so if it is to stay accurate over time, or for different people, there must be some other calculation going on, or more being measured than just a single beats-per-minute... If it's just a calculation with beats vs. time, then in principle any Bluetooth or ANT+ sensor can provide the data to be crunched in an app. If it's something else being measured that the PowerCal sensor is configured to pick up, then it's a different story.

Pastashop
12-28-2014, 12:34 AM
System And Apparatus For Correlating Heart Rate To Exercise Parameters
US 20110288381 A1

https://www.google.com/patents/US20110288381?dq=cycleops+heart+rate+power+meter&hl=en&sa=X&ei=o5WfVLrKIo-ryQSK1YGQDg&sqi=2&pjf=1&ved=0CB0Q6AEwAA


System and apparatus for correlating heart rate to exercise parameters
WO 2011149922 A1

https://www.google.com/patents/WO2011149922A1?cl=en&dq=cycleops+heart+rate+power+meter&hl=en&sa=X&ei=o5WfVLrKIo-ryQSK1YGQDg&sqi=2&pjf=1&ved=0CCsQ6AEwAg

aramis
12-28-2014, 03:25 AM
Used powertaps are so cheap now I would just look for that imho. Saves all the futzing around and lets you actually know.

KonaSS
12-28-2014, 05:39 AM
If I needed a new heartrate strap, I might buy one as the premium over other ant+ straps isn't that great and it might be a fun diversion on my bikes where I don't have power.

If I was truly looking for a tool to measure my fitness......I would save for a real power unit.

Web1111a
12-28-2014, 08:12 AM
Are power tap and cycleops related companies?

Or did cycleops sell the power cal to power tap

Thanks

SpeedyChix
12-28-2014, 08:27 AM
Are power tap and cycleops related companies?

Or did cycleops sell the power cal to power tap

Thanks

Same company. They finally started to use PowerTap as a separate name to help create a standalone identity for the power gear.

If I needed a new heartrate strap, I might buy one as the premium over other ant+ straps isn't that great and it might be a fun diversion on my bikes where I don't have power.

This is what had me pick it up. Needed a HR strap and another speed/cadence sensor so it was a reasonable way to go.

Web1111a
12-28-2014, 12:45 PM
Does gat mean my cyclops branded one can be resold for a premium

:)