I ride both the Specialized Alias and Avatar in regular clothes comfortably (especially the Avatar). The Alias has less cushioning, but is pretty comfortable after a little getting used to it and it is definitely lightweight with a carbon fibre shell and hollow titanium rails.
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Reason is a scoundrel, stupidity is direct and honest. –Ivan Fyodorovich Karamazov
Man's mind, once stretched by a new idea, never regains its original dimensions. –Oliver Wendell Holmes