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How accurate is the Power Tap when measuring cadence?? I have read that it is sometimes erratic.

I have cadence on my current wireless computer... and really find it very useful to know how fast I am spinning.
 

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I have a PT 2.4, and it is quite accurate...you occasionally (a few times in a 3 hour ride)see a one second spike up to 250 rpm or thereabouts in the download file, but I have never seen one reading out on the head unit. Of course, I'm not looking down at it all the time, either.

For $50, you can also buy a PT wireless cadence sensor which mounts on your chainstay and is conceivably less prone to any spikes.
 

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i think when reading from the hub only, it can be off a bit at times, but then gets back in line.
 

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In the normal range, the virtual (calculated, not measured) cadence seems to be reasonably accurate. At high RPMs, i.e., 125+ rpm, it's not accurate at all.
 

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The PT virtual cadence is usually wrong for me. I don't know if I have an especially smooth pedalling style, a poor one, or just don't make enough power. But whatever the problem, it's often 1.5-2x what my real cadence is.


If I cared about cadence, I'd get the extra sensor.
 

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I have used just the hub for measuring and the cadence senor for measuring and they are more or less the same. the hub works off of sensing the pulsing in the hub and then translates that into a cadence number, i find that if im on a bumpy road or i hit a big bump that it throws off the number for a second but then falls right back in line. I just find that the actual cadence sensor is alot smoother in its cadence numbers
 

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I have the 2006 version of the wired PT. It never registers over 150 rpm even though the speed at gearing indicates well over that (I ride the track and can do 200+ rpm as measured by a conventional cadence sensor or by simply doing the math based upon speed and gearing). So my PT is internally inconsistent, hence provably broken at high rpms.

My theory is that their virtual cadence algorithm senses right/left pulse and calculates the rpms based on that - and doesn't have the resolution to sense/distinguish the pulses at the higher rpms. But as I noted earlier, it seems reasonably accurate at typical rpms.
 

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The FAQ says an upper limit of 130. This isn't an "experiment", as I had no control, but yesterday I did cadence drills outdoors, with cadence increasing as the interval length decreased, and I saw an average cadence ceiling of around 120:
 
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