My Mu SL was 20lbs 7oz with pedals and stock tires. I'm sure the current 1.35" Kojaks added a little weight. I believe there were like 2 Helios models that were lighter than that. Don't know why the current crop of folders are as heavy as they are.
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C'dale BBU('05 and '09)/Super Six/Hooligan8and 3,Kona Dew Deluxe,Novara Buzz/Safari,Surly Big Dummy,Marin Pt Reyes,Giant Defy 1,Schwinn DBX SuperSport,Dahon Speed Pro TT,Brompton S6L/S2E-X