Chris King 15mm Conversion Kits: Convert your ISO QR front hub or 20mm front hub into a 15mm for the new QR 15mm forks. Chris King 15mm thru-axle conversion kit is designed to work with standard ISO Disc front hub with 9mm QR axles. The 15QR axle is a collaborative effort between fork and hub/wheel manufacturers to improve the security and performance of the front wheel by replacing the 9mm quick release with a 15mm thru-type axle.