There are times that your bike derailleur is damaged, which prevents the bike gears from shifting. The way to
fix bike gears that won’t shift: You should locate your bike derailleurs accurately. Bike derailleurs are responsible for shifting the bike gear and keeping the bike chain in place. To determine the shifting problem, you can determine whether your bike won’t shift to the highest gear front. Identify the cables that lead to the derailleurs and look for the adjusters. Rotate the cable adjuster anticlockwise if you observe that shifting is difficult while lowering the gear, keep the adjuster tight. Ensure that the derailleur shifts successfully in every turn of the gear wheel.