Technical FAQ: Installing Campagnolo cassettes By Lennard ZinnPublished Aug. 25, 2014 << Back to StoryOpen full size in new window.These are Larry’s remaining cogs. You can see that they are incorrectly installed on the PowerTap freehub body. This is the same problem depicted in the previous photos of the blue Zipp freehub. You can see that this freehub has the same design flaw as Zipp's — it allows the cog to slide on in the incorrect position because the rail just counterclockwise from the freehub body’s stepped rail is angled on its leading edge (rather than being wider and squared-off). The cog’s low step adjacent its narrow tab (aligned with the “11-23B SF3” stamp) is able to slide on over the angled back edge of the rail. When installed in this position, the narrow stepped tab (aligned with the “16A” and “CAMPAGNOLO” stamps) is the cog’s only contact point with the freehub body, and this led to its eventual breakage. Photo: Larry C.