The Hummvee "Waterproof Trouser" is a classic from the Scottish brand Endura. They are available in sizes between S and XXL, but only in black and not separately as women's trousers. They should be suitable for both sexes. The trousers are made of thin, lightweight material and can be folded up very small in the bike bag...

... However, the Hummvee trousers have Endura's Clickfast system: corresponding inner trousers can be connected to the Hummvee with press studs on the inside. However, this only makes sense if the combination is not worn as a cover over the everyday trousers, but as the trousers on their own...