Paul Patzkowsky said "...Benelux mark 7 ... shifting is horrible... freewheel is a 5 speed 13-21... chainrings have 38 and 48 teeth. Is the difference in teeth too much?..."
catalog spec for the Mark 7 is 15 tooth capacity so you're over spec. To use Cyclo on that gearing, use the Tourist (earlier) or the Tourist Mark 8 (later). Both have 35 tooth capacity, and be sure to use the labelled five speed model.
Peter Brueggeman
La Jolla California USA
4peebee(at)peterbrueggeman.com