The optional axle kit for the Topeak Journey TX is available with three different threads (with varying pitch) and is required for 12 mm thru axles with a maximum length of 180 mm. The kits come with various spacers and are designed to fit different thru axle lengths. Note: The thread pitch must match that of the bike. If you have any questions regarding this, please do not hesitate to contact us directly or reach out to your local bike shop. We are happy to assist you.