表示“骑自行车(出行)”,强调出行方式是使用自行车。(也可写作 by bicycle。)
/baɪ baɪk/
I go to work by bike.
我骑自行车去上班。
Even though it was raining, she decided to travel across the city by bike to save money and avoid traffic.
尽管下着雨,她还是决定骑自行车穿过整个城市,以省钱并避开拥堵。
by 在这里表示“通过某种方式/手段”;“by + 交通工具”是英语里常见的方式状语结构(如 by bus, by train)。bike 是 bicycle 的口语缩写,逐渐在日常表达中固定下来,因此 by bike 成为常用说法。