Bicycle MTB T6 CNC Top Cap Expander Bung Headset fit 1" fork Replaces Starnut. Headset Top Cap & Fork Expander Bung 1 "（ Does not fit 1 1/8" fork 28.6mm ）. Expander Bung. Conventional star nuts will scratch the inside of carbon fork steerers which can cause catastrophic failure.
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