Rear Derailer

• 1). Use the rear gear shifter to shift the rear derailer to its outermost position, away from the bicycle frame. Lift the rear wheel and rotate the pedal forward to shift the chain. The chain will shift to the smallest rear cog.
  
  
• 2). Use the rear gear shifter to shift the chain to the next smallest cog. Again lift the rear wheel and rotate the pedal forward to complete the shift. If the chain doesn't shift, or if it hesitates, the derailer cable is indeed loose.
  
  
• 3). Locate the barrel adjuster at the rear of the Shimano derailer. Before entering the body of the derailer, the cable passes through the barrel adjuster.
  
  
• 4). Give the barrel adjuster a one-quarter turn toward the bike. Try shifting again, repeating the procedure from Step 2. If the chain still refuses to shift, give the barrel adjuster another quarter-turn. Continue the adjustment until the chain shifts cleanly.
  
  
• 5). Shift the chain gradually over each of the rear cogs. Whenever the chain hesitates, use the barrel adjuster to tighten the derailer cable. Make small adjustments, and check the adjustment each time.
  
  

Front Derailleur

• 1). Use the front gear shifter to shift the front derailer to its innermost position, closest to the bicycle frame. Lift the rear wheel and push the pedal forward. The chain will shift to the smallest front chain ring.
  
  
• 2). Use the gear shifter to shift the chain to the largest front chain ring. Again lift the rear wheel and rotate the pedals forward. If the chain shifts sluggishly, or not at all, the derailer cable is loose.
  
  
• 3). Locate the front derailer cable barrel adjuster. For road bikes, the barrel will be located midway along the down tube of the bicycle frame. For mountain bikes, the adjuster is found where the cable enters the shifter on the handlebar.
  
  
• 4). Give the barrel adjuster a quarter-turn in the counterclockwise direction. Repeat the procedure from Step 2 above to check the adjustment. If the chain still refuses to shift, continue your adjustment. The adjustment is complete when the chain shifts crisply onto the largest chain ring.