This pair of front end caps is designed to fit 6-bolt E-sync OS and Neo OS hubs when used with older, traditional 20mm axles found mostly on DH forks prior to 2019. 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. 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 |
