This pair of front end caps is designed to fit 6-bolt E-sync OS and Neo OS hubs when used with 20mm Boost axles. The end caps feature a low-friction U-cup seal that snaps into place and stays secure even when your wheel is removed from your bike. DH forks went through a change in disc brake caliper position in 2019, creating a new 20mm Boost fork spacing that differs slightly from previous 20mm designs. More information about the difference between 20mm and 20mm Boost here. Not compatible with Centerlock or non-OS hubs. Not compatible with M-pulse hubs.
Here is a simple, easy-to-understand breakdown of the differences between 20x110mm (Standard/Non-Boost) and 20x110mm Boost front axle standards.
The Short Answer
Both standards use a 20mm thick axle and measure 110mm total width across the fork. However, they are not directly cross-compatible.
The main difference comes down to disc brake rotor placement and how wide the hub is built.
What’s the Difference?
| Feature |
20x110mm Standard (Non-Boost) |
20x110mm Boost |
| Axle Diameter |
20mm |
20mm |
| Fork Spacing Width |
110mm |
110mm |
| Brake Rotor Position |
Closer to the wheel center |
Pushed 5mm further outward toward the fork leg |
| Hub Flanges (where spokes attach) |
Narrower |
Wider (pushed out 5mm on each side) |
| Main Goal |
Older downhill/heavy-duty standard |
Creates a stiffer, stronger wheel |
