Originally Posted by
Godsight
Any TT that is made with a visor will have worse aero drag without the visor.
testing does not bear this out.
There are helmets that test faster with visors, and some that do not.
Additionally, that's not uniform from individual to individual, I had a helmet that tested faster on me with no visor, but faster on a teammate of mine with the visor.
The only immutable rule of aero: "Testing Rules Everything Around Me"