This Is Why Your Bike Gears Won’t Shift and How To Fix Them

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Are you struggling to shift gears on your bike? Shifting issues are something that most cyclists deal with on occasion.

So what causes gears to stick?

Problems with the shifter, derailleurs, and brake cable are the most common reasons why your bike gears won’t shift. If one of these components is damaged or not properly set, the rear derailleur may not shift the chain to a different cassette.

Rear derailleur that is causing bike gears to not shift
There are many components, from the rear derailleur to the gear cables, that can cause your bike gears to not shift properly.

Let’s take a deeper look at why your bike gears won’t shift and how to solve the problem:

How Bikes Shift Gears

If the gears fail to shift, you should inspect the various bicycle parts responsible for shifting. You should also understand how the parts work together to change gears.

Shifters are typically integrated with the brake levers and connected to the brake cable. When you press the shifter, the derailleur shifts the chain from one gear to a higher or lower gear. The gears are held on a cassette.

Bicycles may include only a rear derailleur (which might be equipped with a bicycle clutch) or both a front and rear derailleur. The front derailleur shifts the chain between chainrings. A bike with a 10-speed rear cassette and 3 chainrings on the front has 30 speeds.

How To Troubleshoot a Bicycle That Won’t Shift

Bike gear shifter that might be causing bike gears to not shift

Check the following bicycle components for damage, looseness, tightness, and other issues that may interfere with the movement of the gears:

  • Shifters
  • Derailleurs
  • Limit screws
  • Gear cables
  • Bike chain

If you want to fix the problem, you may need a couple of tools, such as a Phillips screwdriver and a set of Allen keys. You should also grab some lubricant and cleaning supplies to deal with any debris limiting the function of the gear set.

Check for Damage to the Derailleurs

You should first check the derailleurs. This requires you to freely spin the wheels. If you don’t have a bike stand, you can turn your bike upside down.

Visually inspect the front and rear derailleurs for signs of damage and buildup. Make sure that nothing is blocking the operation of the derailleurs. Use a damp cloth to clear away mud, leaves, and debris.

After looking at the derailleurs, attempt to shift gears. Move through the full range of gears, from the lowest gear to the highest. If you notice inaccurate shifting or stiff shifting, the derailleur may be misaligned or damaged.

The rear derailleur hanger should be perpendicular to the rear axle when you’re looking at it from the rear of the bike. The Park Tool DAG-2.2 Derailleur Hanger Alignment Gauge makes it very easy to realign your derailleur hanger:

Park Tool DAG-2.2 Derailleur Hanger Alignment Gauge Check availability

This video shows you how to use the tool to realign your derailleur hanger:

The front derailleur includes a curved section that holds the chain. The outer derailleur cage should be parallel with the chainring when viewing it from above.

This video shows you how to adjust a front derailleur:

Align the derailleurs and attempt shifting again.

Inspect the Tightness of the Limit Screws

If your shifting problems continue, check the derailleur limit screws. The limit screws limit the distance that a derailleur can move to reduce the risk of the chain hitting the spokes or the bike frame.

The screws are typically marked with an H and an L. The H screw limits the outer movement of the derailleur while the L screw limits the inner movement. Move the chain to the smallest sprocket when adjusting the H screw and the largest sprocket when adjusting the L screw.

When adjusting the limit screws, the upper pulley should be perfectly aligned with the sprocket. Check the alignment with both screws.

This video shows you how to properly adjust the limit screws on your rear derailleur:

Check for Damage to the Gear Cables

Sometimes a bike may fail to shift due to a problem with the gear cable or brake cable. The cable may eventually break due to wear and tear. The gear shifter or cable can also get stuck due to buildup.

Open the shifter cover to determine if the cable is broken. If it’s broken, replace it with a new one. If the cable is intact, check to see if it’s stuck. You may need to use a lubricant to get it moving again.

Lubricant may also be needed on the shifter if the cable moves freely but fails to move when you press the lever.

Inspect the Condition of the Chain

Accumulation of rust and debris on the chain may keep the derailleur from easily shifting gears. Debris may be an issue if the shifting action appears sluggish.

Use a degreaser to remove buildup from the chain. The best chain cleaners include a chain cleaning brush that wraps around the chain. You backpedal to pull the chain through the cleaner and remove debris.

An old toothbrush can also work in place of a specialized chain degreaser brush. Apply degreaser to the toothbrush and scrub each section of the chain.

Rinse the degreaser from the chain using soapy water. After the chain dries, apply a lubricant.

Man lubricating bike chain after learning why bike gears won't shift

Most lubricants only require a small drop on each roller for optimal lubrication. Use a clean cloth to remove any excess lubricant to avoid attracting more dirt.

While you’re at it, use a chain checker tool to see whether or not your chain needs to be replaced. The Park Tool CC 3.2 Chain Wear Indicator makes it very easy to determine if your chain needs replacing:

Park Tool CC-3.2 Chain Checker Check availability

Take Your Bicycle to a Bike Shop

Hopefully your bike now shifts properly. But in some cases, you may need to take your bicycle to a professional bike mechanic.

Mechanic repairing bike after learning why bike gears won't shift

Your local bike shop should offer repairs, which saves you the hassle of attempting to troubleshoot the problem yourself. Along with getting your bike to shift again, an experienced bicycle mechanic can ensure that everything is properly aligned.

Last Thoughts on Why Your Bike Gears Won’t Shift

A bike may fail to shift if any of the parts connected to the gear set are damaged, loose, or too tight. Debris may also obstruct the normal operation of the derailleur, making it more difficult to shift.

Always start by inspecting for debris. You should also check the alignment of the bike parts and look for any signs of damage. If all else fails, visit a bike shop.