How to adjust bike gears shimano?

To adjust the gears on a Shimano bike, follow these steps: 1. Start by shifting the chain onto the smallest chainring and smallest rear cog. This will release tension on the cables and make it easier to make adjustments. 2. Locate the barrel adjusters. These are small screw-like devices located where the cables enter the derailleur or shifters. Turning the barrel adjusters clockwise will tighten the cables, while turning them counterclockwise will loosen the cables. 3. Shift to the middle chainring and adjust the front derailleur. Use the barrel adjuster to fine-tune the alignment of the derailleur. If the chain is rubbing against the derailleur, tighten the cable tension by turning the barrel adjuster clockwise. If the chain is having trouble moving up or down, loosen the cable tension by turning the barrel adjuster counterclockwise. 4. Shift to the smallest rear cog and adjust the rear derailleur. Again, use the barrel adjuster to make small adjustments. If the chain is having trouble shifting onto larger cogs, tighten the cable tension. If the chain is having trouble shifting onto smaller cogs, loosen the cable tension. 5. Test the gears by shifting through all the gears and make further adjustments if necessary. Make sure the chain moves smoothly and quietly onto each cog or chainring. Remember, adjusting gears may require some trial and error. It's important to make small adjustments and test the gears after each change. If you're still having trouble, it may be best to consult a professional bike mechanic for assistance.