It doesn't matter when you're out on a bike, relaxed, and everything is going well, but your negligence can lead to accidents. It can also cause different levels of damage, which can be large or small, and if you can know some common sense, you can minimize the damage, and it may save your life at a critical moment. 
If you're out cycling alone, take a few seconds to leave a note or send a message to your loved one or friend telling them where you're riding and when you'll return. Often, riders want to say that it is just a quick ride.
Twenty or thirty kilometers, no special explanation is required. But if no one knows where you're going, it's hard to find you, especially if you're cycling on a remote route, leaving a message is even more important.
Riders must wear helmets when riding, and don't have a fluke mentality! In the unfortunate event of a crash, the probability of a head injury is very high, so be extra careful. In particular, some people may get up as if nothing had happened after a car crash and hit their head. But after a while, you may start to feel uncomfortable, and sometimes you will experience bleeding in the brain, which may even lead to death.
Cracked helmet:Because it means a hard blow to the head.
Headache:It is not the pain of the trauma at the beginning, but the headache that does not alleviate the discomfort of the head after the fall, but gets worse and worse.
Tinnitus:If there is no trauma after a fall, but the ears are always stuffy or there is a buzzing sound, you must do a check-up, most likely brain**.
Vision loss:If you can't see clearly after getting up, you also need to see a doctor.
Another common part of cycling injuries is a blow to the chest with a handlebar or other equipment, but there is no external injury, so many people think they are okay after a crash and don't want to go to the hospital, but are you sure it's okay? At this time, try to take a deep breath, if it is difficult to breathe and it hurts, there is definitely a problem. It is likely that the ribs are cracked, and the cracked ribs may have sharp edges and can puncture the lungs if moved.
There are many soft tissues and organs in our abdomen, which may also be injured by the handlebar collision, so palpate the abdomen with your own hands, if there is a part of the abdomen that is abnormally soft to the touch, it may be an internal injury; If the abdomen becomes swollen or hard, it may also be a sign of visceral bleeding.
Neck and back injuries are serious, and you can usually tell if you're in good shape by examining your fingers and toes. If there is a numbness or tingling sensation, it is most likely a spinal injury; You can also try to slowly turn your head 45 degrees to the left and right, and if you feel uncomfortable, stop and seek medical attention as soon as possible. If there is bleeding from a wound in your body, unless you are a trained professional, don't be careless and just wrap it around it with a tourniquet. If it is judged to be only a skin injury, it is fine, but if it is bleeding due to internal injury, it is a very risky behavior, and it is likely that there will be more damage. The best thing to do is to do basic first aid measures, use clean things to directly pressurize the wound to stop the bleeding, and quickly dial 120 to wait for rescue.
The above injuries are basically judged under your own conscious situation, if the accident is relatively large and you are completely unconscious, what should you do? It is best to carry a personal information card with you before departure, write your basic medical information and emergency contact person** on it, and store it in a wallet or mobile phone case so that emergency responders can easily find it. And can rescue you as soon as possible. If necessary, you can also write down your medication and allergy history to avoid misuse of medication during the first aid process, which may cause more harm.