Alivio is a collection of recreational mountain bike components produced by Shimano. The rear derailleur (one of these components) has the crucial responsibility of transferring the drive chain from one cog to another. These cogs represent a portion of the bicycle’s gears, and without an operable derailleur, the gear selection will be limited. Adjusting the derailleur periodically ensures proper settings (cable tension and range) and optimum shifting performance.
Use the gear shifters on the handlebar and shift the chain to the outermost (smallest) rear cog and outermost (largest) front chain ring. Using a 5mm Allen key, loosen the cable pinch bolt on the underside of the rear derailleur. The pinch bolt secures the derailleur cable to the derailleur.
Stand behind the rear derailleur and observe its proximity below the rear cog (the cog on which the chain currently sits). The two should be perfectly in line. To adjust the position (or range) of the derailleur, use a Phillips screwdriver and turn the high-range screw at the back of the derailleur. The screw will be marked with an "H". Turning the screw clockwise will move the derailleur to the left (closer to the bike).
Turn the adjuster barrel at the back of the rear derailleur all the way in to the body of the derailleur. Once all the way in, give the barrel two turns in the opposite (counter-clockwise) direction. This barrel can be found where the derailleur cable enters the body of the derailleur.
Pull the end of the derailleur cable taught with needle nose pliers, removing all slack from the cable, and re-tighten the pinch bolt on the underside of the derailleur onto the cable.
Use the shifters on the handlebar, and shift the chain to the next rear cog over. If the chain shifts sluggishly (or not all) turn the barrel adjuster on the rear derailleur counter-clockwise until the chain completes the shift.
Use the shifters once again, and shift the chain to the innermost (largest) rear cog and innermost (smallest) front chain ring. If the chain refuses to shift onto this rear cog, the low-range screw on the back of the rear derailleur counter-clockwise. This screw will be marked with an "L". Turning the screw counter-clockwise will move the derailleur to the left (closer to the bike). Ideal adjustment is achieved when the derailleur is positioned directly beneath this cog.