How to micro-adjust your road bike Di2 rear derailleur
Is your rear derailleur not shifting as smoothly as it should? Or maybe you’ve recently learned how to micro-adjust your front derailleur and want to know how to do the same with your road bike rear derailleur? Read on and I'll explain how to make small but effective adjustments to your rear derailleur.
If the term micro-adjust seems a bit strange to you, it is essentially the same as indexing a derailleur - something you might have done before with mechanical groupsets.
Limit screws first?
You may be used to setting up your limit screws before doing any micro-adjustment, but the Shimano manual states that for Di2, it is the other way around. First do micro-adjustment fine-tuning and then set up your limit screws.
Don't worry if you have already set up the limit screws, just know that if you are setting up a derailleur from scratch, you don't necessarily need to set the limits first.
Tip: If your bike has been set up properly you can skip setting the pulley distance and limits, and follow only the steps mentioned under Adjustment Mode.
Check guide pulley distance
According to the Shimano documentation the first step is adjusting the guide pulley distance.
- Shift to the largest sprocket of the cassette
- Turn the end adjust bolt to move the guide pulley as close to the sprocket as possible but not so close that the chain gets jammed
- Shift to the smallest sprocket and check the chain doesn’t get jammed on that end of the cassette either
- If there’s any slack in the chain when the chain is mounted on the smallest chainring and smallest sprocket, adjust the end adjust bolt to eliminate this slack
In order to make adjustments to your rear derailleur, you’ll have to enter adjustment mode. When you’re in this mode the shift buttons will only make adjustments – they won’t let you change gears. This is how it’s done:
- Shift the front derailleur to the small chainring.
- Shift the rear derailleur to the 5th largest sprocket.
- Press and hold the button on your junction box until the red LED illuminates, indicating you’re in adjustment mode.
Easy, right? Now you can micro-adjust your rear derailleur using the buttons on the shift lever:
- Press shifting button X to move the rear derailleur one step towards the inside (larger sprocket)
- While turning the crank/front chainring keep moving the rear derailleur towards the 4th largest sprocket until it makes a slight noise
- The chain now touches the 4th sprocket. Press the Y button four times to move the rear derailleur 4 steps back (towards the 11T).
- Press the junction box button until the red LED turns off. You have now left adjustment mode.
- Now is the time to make any adjustments to your high/low limit screws – if you need to.
Set the high/low end stopper bolts
These bolts limit the range of the rear derailleur, meaning it won’t shift to positions that don’t contain a sprocket. Note that Di2 stopper bolts are different from normal stopper bolts. The Di2 derailleurs slightly ‘overshift’ and then move the derailleur cage back in a. This is intentional, but requires you to set up the adjustment bolts a bit less restrictive than you’d do with a mechanical setup.
If your adjustment bolts are over-tightened you might experience:
- Gears do not shift to the top/low gear or shift back by one gear after about 5 seconds
- Noise that doesn’t stop
- The battery level drops quickly due to extra load being placed on the motor
- The motor may be damaged. (irreparable)
Low stopper bolt
Shift the rear derailleur to the largest sprocket (easiest gear) and then tighten the low stopper bolt until it just touches the left link (of the rear derailleur).
If this seems a bit cryptic: it’ll become clear once you’re doing it – don’t worry. The image below shows what to look for when adjusting the Low stopper bolt. You should be able to figure out the High bolt from this.
Then shift the rear derailleur down three gears and then back to the largest sprocket again. It should shift to the easiest gear just fine.
If it doesn't and you hear a clicking or ticking sound, or if it shifts back within five seconds, relax the limit screw a bit. Don't unscrew it too much though - you don't want the chain to fall off between cassette and spokes.
Top/high stopper bolt
Next set up your high stopper bolt. Shift to the smallest sprocket and then tighten the adjustment bolt until it touches the left link at the position where the rear derailleur stops.
Then, turn the bolt counter-clockwise to loosen it one full turn to allow the rear derailleur to ‘over-shift’. (when it shifts, the derailleur will move slightly past its final position and then move back)
This video describes the process rather well:
Your rear derailleur should be set up perfectly now. Of course, you can always enter adjustment mode again and make small changes but this should be your baseline setup.
Note that while you could do the entire process on the bike, it’s probably best to do it with the bike on a bike repair stand. This will allow you to notice when the chain is touching the 4th sprocket more easily.
The amount of steps you can make differs per hardware series (33 total for 6870, 25 for 9070). If you want to know the number of steps available please have a look at your series’ dealer manual. Alternatively, connect your bike to your Windows computer and use the e-Tube project software to look up the current setting and available steps.