As a final attempt I used pliers to press the plastic case of the HRM at 4 points (next to the two contact points, above and below of both). Squeezing the plastic at three placed had no effect, but one of the four did “repair” the HRM. But only for a while. I repeated the squeeze twice more, but was upset when in the mid of my runs my watches started to show “—” as HR. So that was the time of the dustbin.

I still use the strap, but as I mentioned in some of the blogs here, it was peeling off. Later I glued, but it starts to peel off again.

My whole experiment with Switch up including the accessories was a series of bad news. Never again, I stick to the hated Garmin from now, because at least one can forecast their limitations.

One question regarding the plot comparing Quarq vs Powertap power. I see in the legend that it is written Powertap x 1.10. Does it mean that Powertap measurements are around 10% lower than Quarq measurements in your case?. In other words, are you saying that drivetrain power losses are around 10% for your bike configuration?

Thanks.

Here is another one of interest:

Surprises in cycling aerodynamics

“CFD simulations validated by wind-tunnel measurements
show that drafting also benefits the leading rider,
due to the presence of trailing riders in his wake. The
drag reduction for the leading rider is up to 2.6% with
one trailing rider and up to 3.1% with two or more trailing
riders. The same effects imply that in a group of 6 or
more similarly-sized riders, the position with the largest
drag reduction is not the last, but the one-but-last. The
difference in drag reduction between both positions is
about 1%. In top competitions, where winning or losing
is often a matter of seconds, these drag reductions due
to trailing riders are significant and can be decisive.”
link to europhysicsnews.org