How To Adjust Shimano Nexus 8-Speed Internal Gear Hub (SG-8R20)

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Introduction

If the gear selector isn't reaching its full range on the Shimano Nexus 8-speed internal hub (model SG-8R20), use this guide to properly set the shifting to reach the full shifting range and so that your shifter operates smoothly. This guide also works for Shimano Nexus 7-Speed internal gear hubs.

The internal gear hub system is controlled by how much the shifter (on the handlebar) pulls on the shifting cable, which connects to the internal gear hub. If the cable isn't being pulled by the correct amount, it will not set the internal gear hub to the intended gear.

A common issue in these systems is that the cable stretches over time, causing it to lose tension. If this issue isn’t corrected, the internal gear hub can be permanently damaged because it may end up positioned between gears rather than on a single gear setting.

Before using this guide, ensure that the shifter (on the handlebar) is properly functioning by changing the gearing and monitoring the cable in the rear of the bike (where it connects to the internal gear hub) to see that it is moving.

What you need

Step 1 How To Adjust Shimano Nexus 8-Speed Internal Gear Hub (SG-8R20)

How To Adjust Shimano Nexus 8-Speed Internal Gear Hub (SG-8R20), How To Adjust Shimano Nexus 8-Speed Internal Gear Hub (SG-8R20): step 1, image 1 of 1

Set the gearing to the 4th position on your shifter.

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Step 2

Locate the alignment indicators on the right side (chain side) of the gear hub.
If you see two alignment indicators already aligned, your bike is already perfectly tuned!
If you can only see one indicator (as in picture 1), then your shifting is far out of alignment.
Flip the bike and check the underside indicator.
If the indicator closer the the wheel is further from the front of the bike, tighten the cable.
If you can see two indicators in the window or the underside indicators are within a quarter inch of each other, then skip to Step 5.

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Step 3

Shift to the lowest gear.
Insert a 2.5 mm hex key into the hole on the shifting mechanism and pull the shifter counterclockwise to relieve tension in the cable.
Carefully remove the cable from the shifter.

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Step 4

How To Adjust Shimano Nexus 8-Speed Internal Gear Hub (SG-8R20): step 4, image 3 of 3

Use a set or combination of pliers and/or wrenches to loosen the cable nut.
Rotate the two halves of the cable nut in opposite directions, turning the half facing you counterclockwise.
If the cable needs to be tightened, pull the cable nut away from the end of the cable. If the cable needs to be loosened, pull the cable nut toward the end of the cable.
Use a 2.5 mm hex wrench to pull the shifting mechanism counterclockwise again.
Insert the cable nut into its slot, ensuring the cable sits snugly against the shifting mechanism. Slowly ease pressure off the hex wrench.

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Step 5

How To Adjust Shimano Nexus 8-Speed Internal Gear Hub (SG-8R20): step 5, image 3 of 3

Once the alignment markers are close to each other, adjust the screw on the shifter to fine-tune the cable tension.
Loosening the screw tightens the cable, while tightening the screw loosens it.

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Step 6

If the adjustment screw reaches its limit—too loose and nearly falling out, or too tight to turn—return to Step 3.
If the alignment markers are perfectly aligned, the shifting is correctly set.

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Conclusion

Take your bike for a test ride! If the gears feel easier to shift or you cannot reach a higher gear, readjust the shifting and make sure the cable nut is properly tightened.

One other person completed this guide.