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the most common Zeus steel headset is a model termed the Gran Sport - it is very good

on this model the thread is marked in two places:

a) on one of the spanner flats of the locknut

b) on the "cheek" of the adjustable race

the catalogue states it was offered in metric and in BSC, not in Italian

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here are shown the thread markings on models 2000, New Racer and Cosmos:

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