In Oregon, a bicycle is legally required to be able to stop. ORS 815.280 Violation of bicycle equipment requirements legally requires a bicycle be "equipped with a brake that enables the operator... to stop the bicycle within 15 feet from a speed of 10 miles per hour on dry, level, clean pavement."
What is not defined in that statute is what constitutes a "brake" in the context of bicycle brakes. Since the term is not defined in the statutory law or any case law in Oregon, we must turn to the Webster's Dictionary definition:
"1. a device for arresting or preventing the motion of a mechanism usually by means of friction.
2. something used to slow down or stop movement or activity."
So, a bicycle in Oregon must be equipped with some device that arrests or prevents the motion of a mechanism, or that is used to slow down or stop movement.