Did you ever try it? The Brompton may look funny but ergonomics are similar to a normal bike (in opposite to many other folders), therefor longer trips are not a problem (again in opposite to many other bikes that may look less funny but behave worse). I.e. last weekend a bunch of Brompton-riders here in Germany did the Berlin-Wall-Route in one day - 165km. The third year in a row, it starts to become a tradition. This is the track: Cycling route Berlin | Berliner Mauerweg | GPSies This year not everyone did the whole trip, mainly due to really bad weather-conditions, but some still did. So obviously it is possible to ride longer trips on a Brompton w/o serious discomfort.