Protective helmet and opening for securing the helmet

1. A helmet comprising:

a protective shell shaped to protect a head of a user, the protective shell having an exterior surface, an interior surface, at least two rear vents at a rear end of the protective shell, the rear end comprising no more than a rear quarter of the protective shell, the at least two rear vents each extending from the exterior surface to the interior surface, and at least one opening extending from the exterior surface to the interior surface,

wherein the protective shell comprises an exterior shell and an interior shell, the protective shell has at least a first top vent extending from the exterior surface to the interior surface, the at least two rear vents include a first rear vent and a second rear vent, and the interior shell has at least a first air channel extending from the first top vent past at least one of the first rear vent and the second rear vent, wherein the at least one of the first rear vent and the second rear vent extends across at least a portion of the width of the first air channel,

at least one detachable cap sized and shaped to fit into the at least one opening, and

a tether for retaining the at least one detachable cap such that the at least one detachable cap is operatively coupled to the helmet when detached, wherein the tether extends through the at least one opening when the at least one detachable cap is detached, and wherein the tether is attached to the at least one detachable cap and to the protective shell.

2. The helmet of claim 1 , wherein the helmet includes at least one air scoop operatively coupled to the first air channel at the first top vent such that the at least one air scoop is in fluid communication with at least one of the first rear vent and the second rear vent or the rear end of the helmet.

3. The helmet of claim 2 , wherein the at least one air scoop is detachable from the helmet.

4. The helmet of claim 1 , wherein:

the first top vent is located at a top of the helmet,

the interior shell has a second air channel extending from the first top vent past at least one of the first rear vent and the second rear vent, and

the first air channel connects the first top vent to the first rear vent, and

the second air channel connects the first top vent to the second rear vent.

5. The helmet of claim 4 , wherein:

the interior shell has a third air channel, and

the third air channel connects the first top vent to the rear end of the protective shell.

6. The helmet of claim 1 , wherein the at least one opening is sized and shaped to receive a U-lock therethrough.

7. The helmet of claim 1 , wherein the at least one opening is circular, further comprising a circular ring covering a sidewall of the at least one opening.

8. The helmet of claim 1 , wherein one of the at least one detachable cap or the helmet has a first magnet, and the other of the at least one detachable cap or helmet has a ferrous member or a second magnet, positioned so that the first magnet and the ferrous member or second magnet holds the at least one detachable cap in the at least one opening.

9. The helmet of claim 1 , further comprising means for attaching the at least one detachable cap to the at least one opening.

10. The helmet of claim 1 , wherein the at least one detachable cap has a lip protruding from an exterior surface of the at least one detachable cap, and a cavity beneath the lip.

11. The helmet of claim 1 , further comprising a ledge formed in the exterior shell in the at least one opening.

12. The helmet of claim 11 , wherein the at least one detachable cap has a raised edge on an exterior surface of the at least one detachable cap.

13. The helmet of claim 1 , wherein the at least one of the first rear vent and the second rear vent extends across the entire width of the first air channel.

14. A helmet comprising:

a protective shell shaped to protect a head of a user, the protective shell having an exterior surface, an interior surface, at least one opening extending from the exterior surface to the interior surface, and a plurality of vents, each of which extending from the exterior surface to the interior surface, wherein the at least one opening is sized and shaped to receive a U-lock therethrough, and wherein the at least one opening is entirely positioned on a lower half of the protective shell and on a rear third of the protective shell, said lower half being between a lower rim of the protective shell and a top of the protective shell, and said rear third being closer to a rear end than a front half of the protective shell,

at least one detachable cap sized and shaped to fit into the at least one opening, wherein the at least one detachable cap has a lip protruding from an exterior surface of the at least one detachable cap, and a cavity beneath the lip, and

a tether for retaining the at least one detachable cap such that the at least one detachable cap is operatively coupled to the helmet when detached, wherein the tether is attached to the at least one detachable cap and to the protective shell.

15. The helmet of claim 14 , wherein one of the at least one detachable cap or the helmet has a first magnet, and the other of the at least one detachable cap or helmet has a ferrous member or a second magnet, positioned so that the first magnet and the ferrous member or second magnet holds the at least one detachable cap in the at least one opening.

16. The helmet of claim 14 , further comprising a ledge formed in the exterior shell in the at least one opening, wherein the inner diameter of the ledge is smaller than the inner diameter of the at least one opening.

17. The helmet of claim 14 , wherein the at least one opening is circular, further comprising a circular ring covering a sidewall of the at least one opening.

18. The helmet of claim 14 , further comprising one or more air channels extending between two or more of the plurality of vents.

19. The helmet of claim 14 , further comprising an air scoop attached to the protective shell at one of the plurality of vents.

20. The helmet of claim 19 , wherein the air scoop is detachable from the protective shell.