Main article: Calvin's killer bicycle
On several attempts, Calvin has tried to learn how to ride his bike. His dad even occasionally helps him. But when his parents aren't looking, the bicycle seems to spring to life and attacks Calvin with a vengeance. Calvin can never fully ride the bike without someone helping him, partly out of fear. If an adult is not present, the bike will throw Calvin off the bike and chase after him. Calvin runs for his life, but usually to no avail. He is often hit by the bike and becomes a dirty mess.
In earlier strips, Calvin is shown riding or mentions a tricycle that does no harm to him.
Calvin's dad, on the other hand, will take his bike out on a sunny morning and ride around. He is often seen riding at what the rest of his family calls insane hours.
Calvin's dad sometimes tries his best to teach Calvin how to ride his bike.