ToKnowMore wrote:
Tom A. wrote:
ToKnowMore wrote:
QRNub wrote:
You are not applying force at the hub, the chain is. There are strain gauges within the hub, just as there are crank assembly of crank based meters.Is there any power loss through the chain? Is a crank based power meter more accurate because that is where you are applying the force?
Yes, there is power loss in the drivetrain...but, both types of power meters (correctly calibrated and maintained) are equally accurate. One is just "upstream" of the drivetrain losses, while the other is "downstream".
Personally, I prefer crank-based for monitoring the "engine" (i.e. training purposes) and hub based for monitoring the "load" (i.e. field testing), since both choices reduce the variables for each purpose.
Thank you, Tom. That makes sense. Have you ever ridden with both at the same time and compared the results?
Yes...and it's partly how I discovered I was losing over 10W in my drivetrain due to some "misadjustments"! Of course, prior to this I made sure that the torque slope calibration of the 2 was within 0.5%.
I've also had more than just the 2 PMs mounted to my bike at one time... ;-)
And, in the past, I've ridden with more than just the 2 :-)
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