Any string experts in the house? I've got a 18 strand BCY X string and the serving is a little small for Gold Tip nocks. Anyone no what size I need for 18 strands of BCYX and GT nocks.

.026 Halo for a loose fit.
.030 Halo for a snug fit.

Sorry should have specified BCY power grip is the brand I'd be using, just need to find out which diameter for the 18/BCY X

Agree with Ted, or
just wrap a layer of dental floss around serving at nock position to tighten it up.

I see over 200 views so maybe this will help someone else. The answer for 18 strands of BCYX and power grip serving is .021 for GT nocks. I don't use Halo but I think it is a little smaller than the PG.