Rider-assistance system, data structure, and control method

A control method for a rider-assistance system (1) that assists with driving by a rider of a straddle-type vehicle (10), the control method comprising:

• executing, via an electronic controller (16), a rider-assistance operation to assist with driving by the rider, and further comprising:
• generating, via the electronic controller (16), travel guide information on a curved road (R2) by performing a process of extracting turning travel information based on a parameter from a dataset (D1) including turning travel information on the curved road (R2) acquired by each of plural straddle-type vehicles (10) on the curved road (R2) and/or weighting the dataset (D1) on the basis of the parameter, wherein
• before the straddle-type vehicle (10) enters the curved road (R2), the electronic controller (16) executes the rider-assistance operation based on the travel guide information that is generated by the electronic controller (16), wherein the parameter includes newness/oldness degree information of the turning travel information, and the turning travel information includes information on a swept path.