Originally Posted by
cthenn
Bulk air drag is the number 1 factor in aerodynamics, followed by rolling resistance for bikes. So, probably your position or wind profile is better than others, and/or your tires/pressure/etc are better than others.
+1.
Running slightly larger tires might increase your wheel diameter marginally to account for the marginal increase in your descending speed. Probably a combination of lower drag and better rolling tires.