It is said that Wakyu was made long for durability and strength because it was made from plant material such as wood and bamboo which were less elastic, while Tankyu was made from animal material which were more elastic.
これは高い弾性限界を持つ動物素材を用いる短弓と違い和弓は弾性限界の低い木・竹を張り合わせる植物素材で作られているため、耐久性と威力を求めた結果、長大になったとも言われる。