Cervelo (and maybe others) supply a metal sleeve which you glue inside your steerer after cutting it. The star nut fits into that, so it never touches carbon. That is the only circumstance in which it is permissible to use a star nut inside a carbon steerer.
Cervelo (and maybe others) supply a metal sleeve which you glue inside your steerer after cutting it. The star nut fits into that, so it never touches carbon. That is the only circumstance in which it is permissible to use a star nut inside a carbon steerer.