Originally Posted by
Brian Ratliff
Given the issues with resolving losses that are a two or three of orders of magnitude smaller than the input power (the issue is with subtracting two large numbers, each with independent uncertainties, to assertain a very small number - uncertainty might be well more than 100% of the small number), it is doubtful that Zinn could even repeatably resolve fractional watt losses unless he did the measurement very carefully, or with some clever, robust, indirect method of measurement.
Needless to say, the losses due to seal drag are extremely small. I mean, it is the reason why we now use grease filled, industrial cartridge bearings instead of oil lubricated free bearings for all four bearing locations on a bike. And it's why many pedal bearing systems simply use a journal bearing instead of going through with the expense of using roller or pin bearings.
And, if the price difference were $10-15, then you know that we'd all be rushing out to get this newest latest and greatest thing.
Indeed.
I can't remember if Zinn actually did the test himself or if someone else set it up and he observed/reported on the results. The had a pretty decent testing setup from what I recall, but I would be guessing if I tried to recall any of the specific numbers or their repeatability.
The takeaway from that one was that a well worn in Campy voloce or mirage level square taper sealed BB had the lowest drag of all of them. Shouldn't really surprise anyone who understands what's going on, but it seemed to throw a lot of people.