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fine detective work on your part; you did just fine on your own without any interference from us kibbitzers
there are forum posts which give the history of Sekai and identify the manufacturer(s) of the cycles
recall it was begun by a retail shop owner in the Seattle area
seems to have been active only about four year
REI was a major stockist for them back when the marque was in operation
there seems to have been agreement of folk in the trade that they represented excellent value
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