(1) The operator of a motor vehicle may not: (a) intentionally interfere with the movement of a person who is lawfully riding a bicycle; or (b) overtake and pass a person riding a bicycle unless the operator of the motor vehicle can do so safely without endangering the person riding the bicycle. (2) The operator of a motor vehicle shall yield the right-of-way to a person who is riding a bicycle within a designated bicycle lane.
Right-Of-Way For Bicycles
Mont. Code Ann. § 61-8-320, under Vehicle Operating Requirements.
Mont. Code Ann. § 61-8-320