Are Flip up Helmets Safe?

Obviously modular, or system or flip-up helmets are not as safe as full-face helmets otherwise they would be used in racing. The reputable UK SHARP helmet safety ratings system to which Mark refers shows modular helmets with similar ratings as full face helmets, although less than half received the full five stars.

Can you ride with flip up helmet open?

So on those rules, riding flipped up does not breach the law, if your helmet is British Standard 1869:1960 or ECE 22.05 compliant, but riding unstrapped does. BS alone would be quite scary as it has not been updated since 1975. So, in short. If you want to ride flipped-up the criminal law does not stop you.

Why Modular helmets are bad?

Along with the additional versatility modular helmets provide, there are a few cons. They tend to be a bit heavier in comparison to most full-face helmets. The hinge system and commonly included internal sun visor add weight.