The objective of this study is to develop a model that can estimate when motorcyclists should stop riding due to a decreasing in riding ability caused by aging. Accident rates tend to decrease with the increasing age of riders, but for those aged over 50 years old, the accident rates rise again. The study was conducted in Riau Province, Indonesia, with a total of 860 respondents. Data collection was carried out through interviews. The results show that elderly motorcyclists are likely to have a high level of alertness at 57%, adult motorcyclists at 68%, and adolescent motorcyclists at 75%. Scenario 1 shows that elderly motorcyclists whose vision is obstructed while riding are likely to have a high level of alertness at 47%. Scenario 2 shows that elderly motorcyclists ride on a roads that have roadside variability are likely to have a high level of alertness at 57%. Scenario 3 shows that when elderly motorcyclists ride in fatigued condition, they are likely to have a high level of alertness at 56%. Scenario 4 shows that elderly motorcyclists ride on pothole-ridden roads are likely to have a high level of alertness at 57%. The findings of this study indicated that the riders aged 46 until 65 years (elderly riders) is highly vulnerable to accidents due to having the lowest level of alertness compared to other age groups. Thus, it is recommended that motorcyclists aged 46-65 years (elderly riders) should stop to ride motorcycles.