In today’s tutorial, we’ll learn how to troubleshoot and repair a RapidFire Plus style index shifter. For this job you’ll need a phillips(+) screwdriver, a 4 or 5mm allen key, some light oil, spray grease, and some penetrating fluid like liquid wrench or WD-40.

Sometimes nothing happens if you try to shift up to an easier gear, or down to a harder gear. If your cables are functioning smoothly, this likely means that there is either a build up of gunk on the inside of your shifter, or that some of the internal parts are worn or broken.

Try This First

If it’s just gummed up, sometimes you can get it working again by squirting some light oil inside, and then running through the gears several times to make sure the oil fully penetrates the internal parts.

Look Inside

If not, you’ll have to remove the outer casing and take a look inside. Keep in mind that there are many different styles of these shifters but the concept is generally the same. You don’t want to remove all of the screws on the shifter as there are many small springs and moving parts that are difficult to put back together. Try and see which screw looks like it removes only the dust cover.

With the cover removed, you should see a ratcheting mechanism that includes a gear and a spring loaded pawl. If you run through the gears while looking inside, you’ll see that every time you shift up to an easier gear the pawl pushes against the gear until it clicks it into the next position. This builds tension on the spring and pulls the cable a set amount, which moves your derailleur up one sprocket.

When you use the index lever to shift the derailleur down into a harder gear, the spring releases and causes the gear to slip back one position. This releases the cable a set amount, which pulls your derailleur down one sprocket.

Further Repair

If either of these functions is not happening, inspect the gears and pawls to make sure nothing is broken or looks worn. If they are, you’ll usually just have to replace the shifter. If everything looks fine but the shifter still doesn’t work, you can give it a bit of an overhaul to clean and re-lubricate the inner mechanism.

Disassemble Shifter

You’ll have to remove the shift cable first. It’ll usually slide out the of the shifter when it’s in the highest gear (7,8,9). Then remove the shifter body from your handlebar using the top allen bolt. Unscrew and remove the barrel adjuster and then remove any remaining screws until you can pull apart the dust covers and slide the inner mechanism out. Make sure you pay attention to how everything came apart so you can get it back together again.

Reassemble Shifter

Soak the unit with some penetrating fluid and then wipe it down and let it air dry. Once dry, spray some grease in between all of the moving parts and then re-assemble the shifter parts the same way they came apart. Mount it back on the handlebar and click through all of the gears so the spray grease penetrates. Then replace the shift cable and adjust your derailleur as needed.

If you’ve tried all of these steps and the shifter still doesn’t work, unfortunately it’ll likely need replacing.

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Related Links

• Sheldon Brown: RapidFire

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