Out for a chilly ride yesterday in Philly, and as usual, had all the vents open on my helmet (Shoei RF-1000). And, as usual, had to crack the visor (Shoei has a setting on the visor) because of fog (hot breath + cold air = fog). On the highway, I thought I'd close all the vents ... and ... there it was, clear visor!
My guess? With the bottom front vent washing cold air up onto the visor, combined with hot breath from my nose, you get fog. Close the vent ... no cold air ... no fog. Even stayed clear sitting at lights sitting with the visor closed until it got way too cold (and then I only needed to crack it at the lights--not while riding).
My guess? With the bottom front vent washing cold air up onto the visor, combined with hot breath from my nose, you get fog. Close the vent ... no cold air ... no fog. Even stayed clear sitting at lights sitting with the visor closed until it got way too cold (and then I only needed to crack it at the lights--not while riding).