Gear Issue: How to adjust Shimano Di2 & SRAM eTap AXS drivetrains
The modern bike maintenance checklist goes something like this: check tire pressure, lube chain, charge batteries. Indeed, the advent of electronic shifting drivetrains has forever changed the way we maintain our most precious two-wheeled possessions. So, what are the keys to keeping your Shimano Di2 or SRAM eTap AXS systems properly adjusted?
If your Di2 rear derailleur is out of whack, typically indicated by rasping or chain skip, start by shifting your chain into one of the middle cogs. Then, enter Di2 adjustment mode by pressing and holding the button on your junction box until a red light comes on. By pressing your shift buttons, you can micro-adjust the trim of your rear derailleur by 0.2mm at a time inboard or outboard, until the issue is resolved. Double-check your work by pressing the function button again to exit adjust mode, and then run through your gears.
It’s also worth noting that just like on Shimano mechanical drivetrains, you must assure that high and low limit screws are adjusted correctly, lest you shift your chain into your wheel or frame.
If your Di2 front derailleur is misbehaving, shift into the little ring, and then make sure the gap between your big ring and derailleur cage is between 1mm-3mm and that the cage is parallel with the big ring. If it’s not, make the appropriate positioning changes. Just as with a mechanical setup, double-check your high and low limit settings, making sure your chain doesn’t rub when you’re in your easiest and hardest gears.
SRAM eTap AXS
The rules of thumb are similar for SRAM eTap AXS systems. In the rear, start by shifting into the second largest cog. The pulley wheel should be aligned with the center of that cog. If it’s not, use the system’s micro-adjust feature, which is done by pressing and holding the appropriate shifter AXS button located on the inside of the shift paddle, while also pressing the shift paddle itself.
The right shifter will adjust the derailleur outboard in 0.25mm increments. The left shifter will adjust the derailleur inboard by 0.25mm steps. The derailleur may not appear to move, so watch for the derailleur LED to flash to confirm the command was executed.
To adjust the limit screws, start by shifting the rear derailleur to the largest cog. Then adjust the low limit screw (marked with an L) so that it lightly contacts the inner link of the rear derailleur. Next, shift the rear derailleur to the smallest cog and adjust the high limit screw (H) until it lightly touches the inner link of the rear derailleur.
If you’re still having issues, check the B gap, which is done by installing a chain gap adjustment gauge to the upper pulley wheel, and then using a 2.5mm he wrench, turn the B adjust screw until the tallest teeth of the largest cog line up with the outline on the gauge that matches your cassette size.
If your eTap front derailleur is malfunctioning, start by checking the height. This is done by aligning the tip of the tallest chainring tooth with the set-up line on the inside of the inner derailleur plate. Also assure that the cage is rotated so that the guide marks are aligned with the large chainring.
Then, check that your limit screws are properly set-up. Start by shifting the rear derailleur to the smallest cog and the front derailleur to the outboard position. Now turn the front derailleur high limit screw clockwise to move it inboard or counterclockwise to move it outboard, aiming for 0.5mm to 1mm of space between the inside of the outer derailleur plate and the outside of the chain.
Now shift the chainring to the smallest chainring and the largest rear cog, and turn the low limit screw clockwise to move it outboard or counterclockwise to move it inboard. Again, the goal is to have 0.5-1mm of space between the inside of the inner derailleur plate and the chain.
And no matter which system you’re running, always make sure your batteries are charged. Otherwise none of these adjustments will matter.
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