There's scientific truth to the saying that you never forget how to ride a bike. Even if you can't remember phone numbers, birthdays, or where the hell you parked your car, it's likely that even if you haven't been on a bicycle in decades, you can climb on and ride away just fine. Why? Neuropsychologist Boris Suchan of Germany's Ruhr University Bochum lays it out as best we know in Scientific American:
As it turns out, different types of memories are stored in distinct regions of our brains. Long-term memory is divided into two types: declarative and procedural.
There are two types of declarative memory: Recollections of experiences such as the day we started school and our first kiss are called episodic memory. This type of recall is our interpretation of an episode or event that occurred. Factual knowledge, on the other hand, such as the capital of France, is part of semantic memory. These two types of declarative memory content have one thing in common—you are aware of the knowledge and can communicate the memories to others.
Skills such as playing an instrument or riding a bicycle are, however, anchored in a separate system, called procedural memory. As its name implies, this type of memory is responsible for performance…
According to one idea, in the regions where movement patterns are anchored fewer new nerve cells may be formed in adults. Without this neurogenesis, or continuous remodeling in those regions, it's less likely for those memories to get erased.
"Why Don't We Forget How to Ride a Bike?" (SciAm)