I wish they would ride single file so people could get by, instead of taking up the whole street.
It would be nice if they would ride their bicycles behind one another instead of side by side.
ーI wish they would ride single file so people could get by, instead of taking up the whole street.
「道を塞がないで一列で乗ってくれたらみんな通れるのに。」
ride single file で「一列で乗る」
take up で「ふさぐ・奪う」
ーIt would be nice if they would ride their bicycles behind one another instead of side by side.
「互いの横に並ばないで、後ろに（並んで）自転車に乗ってくれたら良いのに。」
behind one another「互いの後ろに」
instead of「〜の代わりに」
side by side「並んで」
ご参考まで！
カナダ 
