Fork Legs & Tubes
About Fork Legs & Tubes
Fork tubes are the polished inner shafts that slide inside the fork legs, and the legs, also called sliders or lowers, carry the axle and brake mounts. Riders shop here to replace a bent tube after a crash or pothole, to replace tubes whose chrome has pitted and chews up seals, or to change the look or length of the front end.
Match the tube to your bike by diameter, length and finish. Diameters in the listings include 39, 41, 43, 47 and 49 mm, and lengths are given in inches. Finishes include hard chrome, black anodized and gold coatings; they change the appearance and how the surface wears, but the size and length decide the fit. Left and right legs can differ, and leg listings often state the brake setup, such as single or dual disc and whether a factory brake caliper mounts to it. Tube extensions add length and raise the front end, so check fender and tire clearance. A holding tool keeps the tube steady while you work.
Brands listed here include JIMS, Drag Specialties, PSR, Arlen Ness and RACE TECH. Pick your bike in the Ride Finder at the top of the page. New tubes should go in with fresh seals from Fork Seals & Gaskets or a kit from Fork Rebuild Kits. See also Complete Forks and Triple Trees.
FAQs on motorcycle fork tubes and legs
How can I tell if a fork tube is bent?
Remove the tube and roll it on a flat surface, looking for a wobble or gap. A bent tube can cause stiff or sticky movement and leaking seals. Replace a bent tube instead of trying to straighten it.
What does the diameter in a fork tube listing mean?
It is the outside diameter of the tube, in millimeters, and it must match your fork. Look it up in the manual or measure it with calipers. A tube that is off by even a little will not seal or clamp correctly.
Does the finish on a fork tube matter?
Hard chrome is the traditional finish. Black anodized and gold coatings change the look and the surface, but they do not change the fit. Choose by diameter and length first, and then by finish.
Do I need new fork seals when I fit new tubes?
Yes, as a rule. Old seals have worn to the old tube and can leak on a new one, and the fork is open anyway. Fit new seals and fresh oil as the service manual describes.
What do fork tube extensions do?
Fork tube extensions lengthen the fork, which raises the front of the bike by the stated amount, such as 2 inches. This also changes steering geometry and ground clearance, so check fender and tire clearance and the handling afterward.
