How to Go About Troubleshooting Shimano Gears

If your Shimano gears aren’t shifting as well as you’d like, then we’ll show you how to get them clicking cleanly into place.

Prior to working on those gears, you’ll want to clean those derailleurs in situ using a degreaser. Enlist the help of an old electric toothbrush to get at the difficult spots. Then, using Triflon or PTFE based lubricants, lube those main parallelogram pivots.

You should never apply lube outside of the chain. If you’re using a spray lube, make sure to place a newspaper right behind the chain to keep the lube from getting onto the wheels. Then, thoroughly wipe off any excess lube.

When troubleshooting Shimano gears, you may find yourself encountering certain problems that need to be dealt with in specific ways.

Troubleshooting Shimano Gears

Here’s how you go about each issue properly:

The Chain Comes Off (Big Chainring)

So, what do you do when the chain comes off or doesn’t go into the big chainring?

1. Make sure that there’s a millimeter of space separating the top of the large chainring’s teeth and the derailleur cage. If needed, you can loosen the derailleur mounting bolt by two turns and move the derailleur up and down to adjust it to its correct height.
2. Then, set the derailleur cage in such a way that the centerline running through the cage aligns parallelly to the chainrings.
3. The derailleur mounting bolt should then be tightened, and the space between the derailleur cage and outer chain wheel confirmed, these two should not touch.
4. Cable adjusters and down tubes should be turned clockwise to be slacked off. You’ll also want to note that the large chain wheel or high gear stop is normally the outer screw limit.
5. Now, get started with the smallest chain wheel. Proceed to loosen the bolt that fastens the gear cable and pull the gear cable tightly before refastening the bolt.
6. Next, work on the biggest chain wheel and the smallest sprocket. For these parts, you need to make adjustments on the high limit screw so that the cage’s outer plate is about a millimeter away from the chain. Then, shift into the tiniest rear cog.
7. Shift repeatedly to the largest chainrings and adjust the high-limit screw to half a turn until there’s no need to do so as the screw is already adjusting itself without hesitation. Just make sure the screw does not overshoot the biggest chainring.

The Chain Comes Off (Small Chainring)

For this, you just need to follow these steps:

1. Same as the first method, you start by checking the position of the derailleur. Then, you loosen those cable adjusters or downtubes by turning them clockwise fully.
2. Next, you shift to the largest sprocket and smallest chain wheel. From here, you adjust the inner limit screw, which functions as the low gear stop, until there is a one-millimeter distance between the chain and the cage’s inner plate.
3. By repeatedly shifting from the smallest to largest chainring, you should be able to confirm that the chain shifts on its own while not overshooting the smallest chain inward. If you find it necessary, you can adjust the low gear stop screw by half a turn to either prevent over-shifting (clockwise) or to make sure shifts click cleanly into place (counter-clockwise).
4. Most front derailleurs are incapable of shifting on to the smaller chain wheel when you’re pedaling with a heavy load, regardless of whether they’re correctly adjusted or not. In this case, you must coat the spindle threads with refit and anti-seize grease.

The Chain Repeatedly Rubs on the Derailleur Cage

For this problem, here's what you’ll want to do:

1. Move the chain right onto the center chain wheel, which you can do by moving a single click upwards from the small chain wheel, and biggest rear sprocket.
2. Do some adjustments on the cable tension using the down-tube adjuster, so there’s at least a 0.5 mm (1mm is better) clearance between the chain and the derailleur cage’s inner plate.
3. Then, get the chain to move outboard by clicking the front STI lever (just one click). As for the rear derailleur, choose the smallest rear sprocket.
4. Check if you’ve achieved a one-millimeter clearance between the derailleur cage’s inner plate and the chain. If not, continue to readjust the cable tension until you do.
5. Proceed to recheck the clearance when the front of the derailleur has taken the inner trim position, with the chain position on the biggest rear sprocket.

Final Thoughts

Shimano gears that don’t correctly click into place can ruin your entire biking experience. Knowing how to troubleshoot these particular problems is a crucial part of maintaining your Shimano bikes and ensuring your safety on the road. Make sure you know how to identify the source of the gear problem so that you can address it using the right solution.

As it is, we’ve barely covered the tip of the iceberg, so if you want to learn more about adjusting Shimano gears, just read more here.