Only a maximum of one third of the overall length of the extended fork should overhang the original fork, meaning that a minimum of 66% of the fork extension should be supported by the original fork.
As an example, if your original forks are 1200mm, then you may increase them by a maximum of 600mm (50%) using fork extensions.
- A maximum of 50% increased length is allowable
- A maximum of 33% overhang, from original fork, is allowable.