Originally Posted by thugpipe

as far as I can tell all you want is a bike that you can carry up the stairs and might not take up too much space in your apartment, right? have you considered a small wheeled non-folding bike? can't tell your price range but folding bikes are typically heavier than non-folding bikes, you might want to take a look at a bike like the mercier nano or the respect cycles mini velo

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https://respectcycles.com/

both are steel framed bikes but neither is very expensive or particularly heavy, not sure if this is what you are looking for just thought I would throw it out there as an option.