た弾みに / た拍子に【たはずみに / たひょうしに】

た弾みに and た拍子に are used to express that at the very moment some action occurred, something unintended or unexpected happened as a result. Both convey the idea that a sudden, often involuntary movement or event inadvertently triggered an unplanned outcome.

The key nuance is that the result is unintentional and accidental – the speaker did not mean for it to happen. The triggering action is usually something physical or abrupt (stumbling, sneezing, bumping, turning around, etc.), and the result is typically negative or surprising.

た弾みに vs. た拍子に

These two expressions are largely interchangeable, but there are subtle differences:

• はずみ弾み (literally "bounce" or "momentum") emphasizes the physical force or momentum of the action that caused the result. It often appears with actions involving movement or impact.

  ころんだ転んだはずみ弾みに、かぎ鍵をおとしてしまった落としてしまった。

  The moment I tripped, I accidentally dropped my keys.

• ひょうし拍子 (literally "beat" or "timing") emphasizes the timing or coincidence of the moment. It focuses on the instant at which something happened.

  くしゃみをしたひょうし拍子に、こし腰をいためた痛めた。

  The moment I sneezed, I hurt my back.

In practice, most sentences work with either expression.

Structure

Both patterns attach to the た-form of a verb:

• Verb[た] + 弾みに
• Verb[た] + 拍子に

Important notes

• The result clause almost always describes something unintentional – often something falling, breaking, getting hurt, etc.
• These patterns are used for one-time, sudden events, not habitual actions.
• They are common in written Japanese and somewhat formal speech, fitting their N1 level.