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The single most important thing to know regarding the headset on a Styria product is whether the steerer is 26.0mm or 25.4mm in outside diameter. The fact that yours will not accept a 22.2mm stem makes me think it is the 26.0mm size. Since the bicycle is a midliner it could be either size.
Member [MENTION=185430]dddd[/MENTION] has found a replacement headset available online to fit the 26.0mm steerer.
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