Originally Posted by Jim from Boston

My beater bike has a rear rack, and I had a Jandd trunk bag for years, but now I have an Ortlieb roller pannier bag, and I think it meets almost all your requirements, including in contrast to the trunk bag described above, it may well fit a Macbook, and is easy to close. All the other good features apply, but no rear light attachment, though a brightly reflective triangle is on both ends.

It served me well, with enough room to carry all the extra stuff during Boston’s historic brutal winter.