It's crucial to always get contact information after a crash. That's true even if you think that you're fine.
One man was riding his bike when a car near him tried to pull an illegal U-turn. He didn't realize it was illegal at the time, but the car hit him.
He got up, thinking he was fine. The driver stopped and they talked, but they never exchanged information or called the police. Both just agree to go about their business, considering themselves lucky.
Less than a mile down the road, the cyclist started to realize he was actually seriously hurt. He had pain his wrist and shoulder. Eventually, it got so bad that he went to the emergency room.
The problem was that he had no idea who hit him, and he had no way to find out. Even when he was informed that the U-turn was illegal and that the driver was at fault, it didn't make a difference. He couldn't get compensation because he didn't know who to call or who to blame.
At the same time, the driver thought the cyclist was fine. He likely thinks so to this day, not knowing that he actually sent another man to the ER and left him with significant injuries.
After a crash, don't try to determine if you're hurt and then decide what to do. Always get the proper contact information. In the vast majority of cases, it's typically best just to call the police. Yes, it can be a hassle, but it also means you can actually use all of your legal options in the future.
Source: Active, "How to Handle a Bike Accident With a Vehicle," Ryan Wood, accessed Oct. 03, 2017