aka_finto wrote:
Has there actually been any direct testing of rim brakes vs. disc that proves that discs are actually slower? I'd assume the disc brake itself causes drag, but can that not be offset?
Yes. http://www.tririg.com/...irst_Look&num=33
That's one of the best examples since it's the most "apples to apples" comparison (i.e. aero optimized design for both technologies)
Also, IIRC, in the comparison of the Venge Vias and the Venge Vias Disc, the disc version was still slightly slower, even though they had a second chance at designing the disc version and built on the "lessons learned" of the orignal rim brake design (which started as a disc design, and then mid-stream was changed to a rim caliper design, i.e. "compromised")
Many of the test examples typically pointed to which show "little or no difference" are comparing a disc design against a non-aero optimized rim caliper setup and/or don't account for the lower spoke counts allowable for equivalent wheel strength on rim caliper designs...and then don't look at the translational AND "power to rotate" drag hits for the higher spoke count wheels necessary for separate braking discs. It's not a true "what's the best I can do with either technology" comparison in regards to aerodynamics.
http://bikeblather.blogspot.com/