bicycle helmets prevent head injuries image
Forgetful
There is a "shell" and a "liner" in a bicycle helmet, right? what is the purpose of those things? Is the shell supposed to stop it from breaking or is the liner supposed to be crushed?
Simple language please.
thanks!!!!!
Answer
There are variations depending upon the quality of the helmet and the purpose... for example, some DH helmets are practically MX helmets now but, in general...
Bike helmets have the liner and shell as you've mentioned, the liner actually does the majority of work in saving you from a fall. The shell is really just there to prevent things like stick and such on the tral from penetrating the liner and stabbing you in the head, or to keep the liner from coming apart on hard impacts. The liner is what handles the energy transfer that prevents you from sustaining severe injury. When you take an impact, the liner is supposed to get crushed... in doing so, it converts the kinetic energy (the energy of an object in motion) of the impact into thermal energy (heat) as the liner is crushed. Remember, energy can never be created or destroyed, it can only change forms... The type of material used in the liner and the overall quality of the helmet determine just how effective it is but that's the basic principle in ALL helmets actually. Most common helmets use an EPS liner, Expanded PolyStyrine, and are good for just one serious impact... Once the liner has been crushed, it no longer has the capacity to be crushed much further to allow for the conversion of energy needed to protect your head. Some other helmets use materials that allow the energy conversion to take place repeatedly and only need to be replaced if the shell material is compromised... these are typically MX helmets or very high-end downhill helmets.
Also, it's worth noting that essentially all bike helmets pass the same certifications so there isnt a whole lot of difference in protection between a $40 helmet and a $140 helmet... Most of the extra money that you pay goes into what was spent on R&D to figure out a way to incorporate more vents into the helmet without lessening the protection offered.
There are variations depending upon the quality of the helmet and the purpose... for example, some DH helmets are practically MX helmets now but, in general...
Bike helmets have the liner and shell as you've mentioned, the liner actually does the majority of work in saving you from a fall. The shell is really just there to prevent things like stick and such on the tral from penetrating the liner and stabbing you in the head, or to keep the liner from coming apart on hard impacts. The liner is what handles the energy transfer that prevents you from sustaining severe injury. When you take an impact, the liner is supposed to get crushed... in doing so, it converts the kinetic energy (the energy of an object in motion) of the impact into thermal energy (heat) as the liner is crushed. Remember, energy can never be created or destroyed, it can only change forms... The type of material used in the liner and the overall quality of the helmet determine just how effective it is but that's the basic principle in ALL helmets actually. Most common helmets use an EPS liner, Expanded PolyStyrine, and are good for just one serious impact... Once the liner has been crushed, it no longer has the capacity to be crushed much further to allow for the conversion of energy needed to protect your head. Some other helmets use materials that allow the energy conversion to take place repeatedly and only need to be replaced if the shell material is compromised... these are typically MX helmets or very high-end downhill helmets.
Also, it's worth noting that essentially all bike helmets pass the same certifications so there isnt a whole lot of difference in protection between a $40 helmet and a $140 helmet... Most of the extra money that you pay goes into what was spent on R&D to figure out a way to incorporate more vents into the helmet without lessening the protection offered.
Do I need a permit or license for cycling in NYC?
YD
I am a cycling newbie that recently get a hybrid bike, so I just wonder if I need any bike license or need to follow any bicycle traffic rules? Like helmet is required or what if there is no bike route and something else. And how can I prevent bike stolenï¼ I bought an U-lock and cable lock, and I am gonna bring off the the front wheel and saddle every times, is it good enough?
Many thanks
Answer
Nope, you wouldn't need any permit or license or any of them trouble things to ride a bike in NYC. Just get on it and revolutionize the crank and pedal! But as a cyclist, you do need to follow the traffic lights, such as stopping at red lights. And because you're cycle, you are gonna need a helmet for sure to minimize the risk of having a head injury. There's no such thing as a "No Bicycle Route", just cycle on the roads and follow the traffic rules, do not ride on the pavement like a jerk. No, that's really too troublesome, just get three U-Locks and lock both of your rear and front wheels to the frame and another lock to lock the frame to a permanent structure.
Nope, you wouldn't need any permit or license or any of them trouble things to ride a bike in NYC. Just get on it and revolutionize the crank and pedal! But as a cyclist, you do need to follow the traffic lights, such as stopping at red lights. And because you're cycle, you are gonna need a helmet for sure to minimize the risk of having a head injury. There's no such thing as a "No Bicycle Route", just cycle on the roads and follow the traffic rules, do not ride on the pavement like a jerk. No, that's really too troublesome, just get three U-Locks and lock both of your rear and front wheels to the frame and another lock to lock the frame to a permanent structure.
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Title Post: How do bicycle helmets work?
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