Ortlieb are the EU go-to for these kinds of bags: https://www.ortlieb.com/en/hinterradtaschen/ https://www.ortlieb.com/en/hinterradtaschen/ You can find cheape

Ortlieb are the EU go-to for these kinds of bags: https://www.ortlieb.com/en/hinterradtaschen/ https://www.ortlieb.com/en/hinterradtaschen/ You can find cheaper but these bags are very durable. They’ll last many years.