The Rhine Cycle Route between Bingen and Remagen (left side of the Rhine) is built as a separate cycling path and can be cycled fairly easy. The path sometimes follows the banks of the river closely, sometimes it leads through the towns and along the promenades and sometimes the path is built as a separate cycling path next to the roads. It is thoroughly signed with the official EuroVelo 15 signet.
A trip along the Rhine Cycle Route surely belongs to the most scenic ways of discovering the unique cultural landscape of the Romantic Rhine. The region offers two UNESCO World Heritage Sites: the beginning of the Upper-Germanic Rhaetian Limes in Rheinbrohl and the Upper Middle Rhine Valley lies between Bingen/Rüdesheim and Koblenz. All of the neighbouring rivers that issue into the Rhine, like the Nahe, Moselle, Lahn and Ahr, offer cycling paths along the river as well. That way you can easily combine a cycle trip along multiple riversides.