Tube Forks, Not Tube Socks!

Jul 21, 2010

While most people are familiar with this form of fork, (not to be confused with the one you eat with) many have no idea what is actually going on internally with this component. Here’s the scoop. A tube fork incorporates an internal shock and spring in one sealed cylinder unit. The smaller tube slides in and out of the slightly larger tube that is sealed around it. Sound pretty simple, right? The more detailed mechanics of it are that the internal springs and hydraulic fluid serve to dampen the movements of the tube forks to smooth out the ride, (providing the active suspension for the front wheel).

Traditionally the rigid portion of the tubes are joined to the frame, via the triple trees, while the wheel axle is fastened to the active (live) forks. (NOTE TO SELF: Hydraulic fluid levels should be checked periodically to insure proper operation). Tube forks are available in conventional (traditional) and inverted configurations. Conventional tube forks have the smaller tubes fixed to the triple trees, while inverted tube forks have the larger tubes mounted to the triple trees. Both configurations essentially work the same way. Inverted tube forks have been used on sport bikes for years and can be found on a number of bikes built by Guilty Customs. Tube forks provide good dampening qualities for most applications where rake (angle from vertical) does not exceed 35 degrees. When used in higher rake applications the dampening affect will be reduced by side-loading stresses (aka pinch points) exerted on the tubes.

Tube forks are manufactured in several diameters, widths (distance between fork centers) and lengths. 41 and 39 millimeters are the industry standards for tube diameters, though other offerings are available. Fork widths vary from 10 inches (H-D Wide Glide) to narrower (Sportster) styles. Some manufacturers have recently introduced the Mid-Glide widths that fall in between the wider and narrower styles. So, whether your up for wide vs narrow vs mid-glide, rest assured that the tube fork has had years of use and refinement for pretty much any application. Now, where is my dinner fork, i’m hungary!

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