Modern derailleur systems use very narrow chains that won't tolerate being dirty. A hub gear setup with a 1/8" chain (or an old 5-speed derailleur setup) will t

Modern derailleur systems use very narrow chains that won't tolerate being dirty. A hub gear setup with a 1/8" chain (or an old 5-speed derailleur setup) will tolerate much more abuse. A traditional roadster bike (stadsfiets) with full-length mudguards and an enclosed chaincase throws much less dirt into the drivetrain than a sporting bicycle with neither.