ローラー台だい

noun

bicycle rollers

A training device consisting of rotating cylinders on which a bicycle is placed, allowing the rider to cycle indoors while the bike remains stationary.

• 冬ふゆは外そとで走はしれないので、ローラー台だいで練れん習しゅうしている。

  I can't ride outside in winter, so I train on bicycle rollers.