I'm interested the "Da Brim" for sun protection, but since it is mostly out of stock at the moment, I'm left to deliberate my decision to buy one. What I wonder is to what degree the brim affects the helmet's protection. It seems like the brim would be crushable and not likely to severely deflect or rotate the helmet provided the strap was adjusted properly. This is only speculation though, and without any evidence.
According to
https://helmets.org/visors.htm , there appears to be some concerns with hard plastic visors causing lacerations. This would not be a concern with a soft brim. The same site
https://helmets.org/helmet22.htm also published, "
We recommend looking for a helmet that fits you well, pleases you as wearing apparel and has a rounded, smooth exterior with no major snag points."
The "rounded" shape is something that is proven. Arai, a premier motorsports helmet producer, has since the 1970's maintained a loyalty to what they call their R75 shape -- a round shape with a minimum of 75mm radius curves. https://parts.araiamericas.com/the-arai-difference/r75 I am a loyal Arai user for over 25 years. Some independent tests have shown the R75 shape to be just as effective as MIPS at managing rotational energy. This is an objective fact that can be measured. I do appreciate that what this means for injury is much more ambiguous. It seems intuitive to me that a round helmet will direct forces tangentially whereas a helmet with sharp radii, protrusions, or square edges has the potential to snag, increase neck torsion, and especially in the case of a lower-coverage bicycle helmet, deflect the helmet out of the position that's necessary for maximum protection.
I am currently looking to replace my helmet, a Giro MIPS model, simply because it is worn out, and to possibly add Da Brim so I don't have to goop-up my face, head and neck so much.