I recently switched a pair of mavic aksiums with a pair of mavic cosmos wheels(old 19mm rim 20f 24r). Same bike, same set up and tyres.
Aksiums based on kysriums but heavier. Cosmos built on something that resembles an open pro rims. Hubs on both are cartridge, but aksiums have mavics new style chunky hub while cosmos have smaller profile.
The aksiums are significantly slower going downhill. Anecdotally, the cosmos seem to keep up with zipp, mad fibre, other carbon rims when coasting down steep grades.
I have the opinion it is not equipment but rider. However, this is one situation where I notice a significant performance decrease. Any ideas why?
I didn't find the right solution from the internet.
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