ホイールに剛性があると、・・・の安定性は増す。

Rigid wheels give sufficient stability to a low-speed vehicle steered by outside forces.

見た目には優しそうだけど、彼って皆から外柔内剛の結構なタフネゴシエータと言われているよ。

He seems like a softy on the surface, but at the core he's got an iron will that makes him an extremely tough negotiator.

なるほど彼は剛速球投手だが、よく荒れる。

It is true he has a good fast ball, but he is often wild.

彼女は１０マイル競争を走るほど剛健だった。

She was strong enough to run a 10-mile race.

柔よく剛を制す。

Soft words win hard hearts.