When they were introduced in 1965 to the Keihin-Tohoku Line, where distances between stations is longer than two kilometers, their suitability as commuting cars was tested by adjusting the gear ratio for a little bit more high-speed or by using MT54.
ただ、昭和40年度から2キロ台の駅間距離のある京浜東北線での運用開始に際し、103系のギア比を少し高速よりにセッティングする事や、MT54による通勤電車の可能性を模索した。