dangle wrote:
GreenPlease wrote:
The hub based ones are not
precise enough for VE testing.
Genuine question, is there anything to back up that statement?
Thanks for the replies. I had just been a hardcore lurker in this thread until today. I really only care about A:B testing, so it's
precision that I'm after vs. accuracy. After perfectly matching two B runs last week, I was feeling good until seeing these links. Thanks for contributing to a great thread.
Edit: The DCR link above also said that he was using it on a big Powertap hub (transmitting it's own info) and Saris/Cycleops said that it was likely causing interference. DCR said he would have an update in the Edge 1000 review after trying it on a different wheel. I clicked over to that and the speed sensor data is WAY cleaner and he said he had no problems recommending it now.
The exact page is here. The exact text is below:
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In my initial testing in my earlier post I saw some oddities with speed and noisiness of the data using the new sensor, compared to traditional magnet-based sensors. Garmin did some poking and believed it was due to the new sensor being installed on a PowerTap hub, which they believe may have introduced some electronic interference. So instead, I moved it to both a different wheelset, as well as to the front wheel. In doing so, here’s the data I saw on about a 90 minutes or so ride:
(Note: Data is in wheel rotations, in order to ensure everything matches exactly, it’s not in precise speed which is simply a function of the wheel circumference) Here’s a smaller section (1,000 to 1,800) zoomed in:
And, zoomed in one step further (250-500 of the above chart):
As you can see, it’s far cleaner now, and I’d have no problems recommending it.
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This would lead me to believe that there's no reason the magnetless sensor wouldn't work. Or more accurately, it may invalidate the reasons above against using the magnetless sensor.