The world of hub spacing can be somewhat daunting as there are an array of axel diameters and spacing options out there. You are likely buying a wheelset for a specific bike so the best way to confirm your hub spacing is to look up the make, model and year of your bike and confirm the spacing within the build spec. Alternatively, you can remove your front and rear wheel, use a set of calipers and measure hole diameter and hub width to determine your spec. Below are the most common hub spacing specs: Boost Front: 110x15 Boost Front DH: 110x20 (newer DH forks) Boost Rear: 148x12 Super Boost Rear: 157x12 Road Front: 100x12 Road Rear: 142x12 If you have any questions or would like to confirm your hub spec you can Contact Us, we're here to help!