How Long Of Fork Extension Can I Get For My Forks?
Putting too long of an extension on your forks poses a safety problem. The added leverage on the extension places an incredible amount of force on the underlying forks, frame and host machine. Also, because fork extensions are built hollow to accommodate the host forks, they are not as rigid, and can fail when used improperly.
The Occupational Health and Safety Administration (OSHA) has created guidelines and regulations that you should familiarize yourself with when using fork extensions.
In general however, fork extensions should not be longer than 50% of the host forks. For example, if you are purchasing 72” fork extensions, your host forks should be at least 48” long. Anything longer than a 72” extension on a 48” fork will not work.