How To Fix Mountain Bike Gear Shifter

The gears on the back of the bike are controlled by a shifter. This is usually a lever that moves up and down or side to side. The gear shifts by moving the lever one way or another, which moves the chain onto different sprockets.

When this is not working correctly, it can be difficult to know what to do. There are many things that can go wrong with a shifter and it’s important to diagnose what is causing the issue before fixing it. If you are not sure how to fix your shifter, there are some steps you can take to troubleshoot and figure out what needs adjusted or replaced.

Why are my gears not shifting on my mountain bike?

This is usually caused by an overly tight gear cable or the low limiting screw that needs adjusting. You can test this by shifting to the lowest gear and seeing if your front derailleur is in line with the smallest chainring. If not, try adjusting the limiting screw. Alternatively, your gear cable may be too tight.^[1]

What causes gears not to shift?

Over time, dirt, debris and other tiny particles can accumulate in the transmission fluid, affecting its fluid properties. This can cause the vehicle to die when you shift into drive or reverse, allow a loss of power, transmission slip, rough shifts or even prevent the vehicle from shifting into gear at all.^[2]

Do bike shifters wear out?

Shifters can wear out too (if you ride enough), and most cannot be serviced back to health. But before you go sinking money into these more expensive components, best try a new cable/housing or get a second opinion.^[3]

How does a twist shifter work?

Twist shifters are used by twisting the shifter — placed over the handlebar and serving as the rider’s handgrip — forward or backward to make the gears move up or down. Mountain bikers prefer twist shifters so they can change gears without taking a hand off the handlebars and potentially losing control of the bike.^[4]

Why is my derailleur not shifting down?

If derailleur does not succeed in shifting the chain into the next largest ring or hesitates, add cable tension. Once you get to the largest cog, shift back into the smallest rings. If there is any hesitation or the chain will not shift back into the smaller rings, remove cable tension until the shift is successful.^[5]

How can I make my bike shift better?

Most often if your shifting is sluggish in one direction you can improve it by turning the barrel adjuster. As always, make sure all drivetrain components are tight, clean, and properly lubricated. If shifting is slower toward easier (lower) gears your shift cable is likely too loose.^[6]

Why do my bike gears keep jumping?

Gear indexing issues One of the most common reasons for a skipping chain is simply a drivetrain that needs a simple indexing adjustment. This is so common that even many brand new bikes can exhibit these symptoms. The good news is that this is probably the simplest to diagnose and fix of all potential issues.^[7]

How do I know if my shift linkage is broken?

Grinding noise. If you notice a grinding sound from the transmission, it may be due to clashing gears. Odd sounds like thumping, bumping, squealing, and whirring. The odd noises coming from the shift linkage may be due to insufficient oil. Transmission oil leaks.^[8]

How do I know if my gearbox is damaged?

Check for gearbox fluid leakage. Check dashboard warning lights. Gears become unresponsive. Listen for any unusual sounds. Beware a shake, jerk or grind. There might be a rumbling in neutral.^[9]

What causes stiff gear changes?

This happens because, if the master cylinder and/or release cylinder is damaged or leaks, it can cause loss of pressure on the fluid, this can make the clutch not disengage properly. If the clutch and engine do not disengage properly, the manual transmission will be hard to shift all gears, or fail to shift entirely.^[10]

How long do bicycle shifter cables last?

the front shift cable also lasts years. the rear, it depends on which bike, but generally lasts 1.5 to 2 years. after the initial cable stretch, there is nothing to be done for a long, long time.^[11]

Why does my bike shift hard?

If your motorcycle is having a hard time shifting gears, it could be due to a dragging clutch. This means that the clutch disk drags and fails to disengage when you press the clutch pedal. The clutch is spinning with the engine which makes it nearly impossible to change gears.^[12]