Testament TN wrote:
How are any of these tests considering suspension related energy/power losses. Rolling resistance really only a part of the system and frankly an order of magnitude less significant than energy lost through getting rattled around - hence the need for supple tires run at the lowest possible pressures.Are you referring to "suspension losses" in the sense that Jan Heine has co-opted the term? That is, talking about losses from energy that gets THROUGH the tires (usually due to running too high of pressure for the conditions) and is dissipated in the rider? I find that terming it that way can be confusing since on a rigid bicycle, the tire IS (or should be) the suspension.
Think of it this way, in order to prevent those losses, it's incumbent on the rider to choose the correct pressure in order to avoid the "breakpoint" pressure (where resistance to forward motion dramatically increases - because the tires are no longer acting effectively as suspension)...and if they can't lower the pressure enough without bottoming, then they should choose a larger tire. All of that has little to do with the inherent losses in the casings of the tires themselves.
However, if the pressures AND tire sizes ARE selected adequately, then the tire is doing its job as suspension, and the REAL suspension losses are from the additional dynamic casing flexion on top of the fixed amplitude deflection caused by the wheel loading....and the losses from both types of flexing are driven by the internal hysteretic losses of the tire/tube construction...of which, a smooth roller test is a great method of determining. This also explains why adding "texture" to a roller isn't necessary. So, if you aren't over-inflating your tires and/or using too small of tires for the conditions, then the rolling resistance contribution of the tire is absolutely driven by how "lossy" the tire construction is.
So, that's a long answer to your question...so in short, the roller testing captures the real suspension losses of the tires by measuring the tire hysteresis losses. It does not capture any additional losses in the system caused by running pressures above the breakpoint pressure of the system (what Jan confusingly calls "suspension losses")...but you shouldn't be doing that anyway.
I know Jan has a bit of a "blind spot" on this, and can't quite wrap his head around the utility of roller testing...which is why I thought it would be good to more thoroughly explain.
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