How to Repair Timberline Bikes

The Timberline is a hardtail mountain bicycle built by GT. A hardtail refers to the back end of the bicycle having no suspension system. Over time a bicycle requires repairs or tune-ups, and the Timberline is no exception. Depending on the issue, repair the Timberline in your own bicycle workshop. Novice mechanics should fix issues like flat tires, loose brakes or sour shifting off the derailleurs. For more advanced repairs, study and do the repair with an experienced mechanic to prevent injury.

Things You'll Need

  • Bicycle workstand
  • Fully equipped bicycle workshop
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Instructions

    • 1

      Place the Timberline in the bicycle work-stand. Turn the pedals and shift through the gears, watching for any loose shifts on the rear cassette -- the toothed metal rings in a cluster in the center of the rear tire. If there are sloppy shifts, locate the barrel adjuster on the rear of the back derailleur. This is the black plastic barrel where the cable attaches to the derailleur.

    • 2

      Turn the barrel to the left to loosen the shifting, or to the right to tighten. Make one-quarter turn adjustments and turn the pedals going through the shifts until the rear cassette shifts smoothly and no gears are missed. For the front shifter/derailleur go to the shifter on the left hand side handlebar and find the barrel adjuster at the cable connection. Turn in one-quarter increments to the left or right until the front shifts through the three chainrings next to the pedal cranks.

    • 3

      Squeeze both handlebar brake levers. If there is slack in the braking, turn the brake barrel adjusters -- at the end of the brake levers -- to the right to tighten to your desired setting.

    • 4

      Grab both sides of the pedal cranks. The cranks are the large circular fixtures the pedals attach to. Forcefully try to pull and push them in toward the bicycle or out from the bicycle. If there is motion like this, use an Allen wrench and insert it into the center Allen screw. Tighten the screws on both sides of the crank by turning the wrench clockwise as tight as possible.

    • 5

      Turn the cranks and hold the bicycle chain oil at the back end of the rear derailleur. Squirt oil/chain lubricant over the chain as it spins over the cassette. Let this oil soak in to alleviate rust build up or grungy chains.