Suppose you have a frame with a 1-1/8" to 1. 5" tapered head tube and a fork with a 1-1/8" straight steerer tube. It's not a problem, you simply need this 110-Series 52/30 Conversion Crown Race to adapt the fork's 30mm o. d. crown race seat to the 1. 5" lower bearing in your Cane Creek Headset. While we also sell the 40-Series version (and it's exactly the same dimensions as this one), this 110-Series Crown race is their finest offering. It's made of stainless steel and features a Dual-Seal to mate with the lower cup to keep out any gunk that could hamper your headset function.