Girvin Flexstem: Mountain Bike [F Handlebar]

Sellers Description: Girvin Flexstem Mountain Bike   Condition: NEW IN BOX!
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Girvin Flexstem: Mountain Bike [F Handlebar]

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The extension Girvin refers to as a "dog bone" because it has two large joints at the ends of a smaller cylinder, like the caricature dog bone has. The extension is made of Cro-moly steel, and painted in Taiwan. It has a 28.9mm diameter cro-moly steel tube TIG welded, perpendicular to the extension at each end. At the quill end, there is a drilled out steel plate, with several "breaks", (bends in the metal to give it structure), creating a box shape that reinforces the quill/extension swivel against metal fatigue and failure. The quill end tube has a Delrin, (Teflon-like material that has a slippery surface), bushing pressed into each side.

This bushing surface is what the extension swivels up and down against. Through the bushing, a machined aluminum rod, that is threaded, end to end, is pressed. This serves as the axis point for the swivel. The extension at this point slides into the quill head. From the outside, on both sides, machined aluminum caps, (like the ones used on the top of quills on other stems), with bolt head recesses are slid in. The back of the cap is turned to a 15.9mm diameter which passes through the arms of the head into the machined rod in the extension, then a bolt goes through the cap, arm, and threads into the machined rod. This forms a very stable and well supported swiveling arm.

Beneath the arm, is the shock absorbing bushing, which slides over a hollow steel spindle, then the box shaped plate rests over the spindle, with another bushing, then a steel plate that has the brake cable "macaroni" welded to it. A bolt goes through all of these pieces and anchors in the tubing, bonded inside the quill head. It's less complicated than it sounds, but there's no better way to describe how solid the joint is. The binder fitting is made of machined steel rod, that's drilled and tapped for the binder bolt, welded to the front of the tube, then the tube is cut through to make the cinch system.

The expander bolt is made of chrome plated steel and has thin steel washer to reduce friction when tightened. It is 135mm long, with 8mm threads by a 1.25mm thread pitch, has a 6mm hex head, and weighs, with washer 48 grams. The binder bolt is made of nickel plated steel, has a 6mm hex head, with 6mm by 1mm thread pitch, is 20mm long, weighing 6 grams. The wedge is made of cast aluminum, with light machining to finish it's shape and tap the threads. The extension on the Flexstem comes painted in a Pearl Grey or Glossy Black color. The stem is made in 100mm, 120mm, 135mm, and 150mm extension lengths, in the 1", 1 1/8" or 1 1/4" diameters.

The elastomer bushings will last between 6 and 12 months of rigorous use, then should be replaced. Replacements are available though us, below. All Flexstems come from the factory with the Red, (medium density), elastomer bushing, and fit 25.4mm diameter handlebars without a shim. A 135mm long Flexstem with a 1" diameter quill weighs 511 grams. Specify length, diameter and color when ordering.

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