Welcome to the Workshop Series, today we’ll be guiding you through the rear derailleur adjustment for a mechanical, or cable activated groupset.
The basic tools you may need for this job are: a 2mm hex key and a phillips head screwdriver.
The reason for this adjustment would be if you’re experiencing slow or inaccurate shifting.
First things first, before starting any work on your drivetrain it is important to clean it. Many times dirt and grime will negatively affect the shifting performance. If you need a hand with cleaning your drivetrain, please see the link for that video in the description below.
Another critical factor for smooth and accurate shifting is the rear derailleur hanger alignment. See, the hanger is a safety device intentionally made out of a very soft metal, so in the case of a crash or impact, the hanger will absorb most of the forces by bending, preventing more expensive parts, like your derailleur or frame, from getting seriously damaged.
To check and align the rear derailleur hanger we need a professional and very specific tool called ‘hanger alignment tool’. If you happen to have a bent hanger and do not own one of these tools, we would recommend taking the bike to your local shop to have the hanger aligned.
LIMITER SCREWS AND B-TENSION ADJUSTMENTS
Now we’ve ensured we have a clean drivetrain and an aligned rear derailleur hanger, we can start with the actual adjustments. Having the bike on a working stand makes it a much easier and pleasant job. If you’re not lucky enough to have a bike stand, you can ask a helping hand to hold the bike up by the saddle, keeping the rear wheel off the ground while you perform the adjustments.
Firstly let’s check and adjust our limiter screws. Shift to the highest gear, or smallest cog on the cassette. Spin the pedals continually and check if the chain drops of the cassette, if it does we need to adjust our high limiter screw - it should be marked with the letter ‘H’. Screwing clockwise will move the chain in, towards the bike. Do small adjustments at a time, while checking the results, this would allow you to return to the previous adjustment in case you go too far.
With the high limiter set we can move on the low limiter screw. Keep the chain in the same cog, and while spinning the pedals push the derailleur body with your thumb as far as it goes. Be careful here, as in case your low limiter is not set correctly you run the risk of throwing the chain off the cassette, and it could potentially get stuck there - no good.
What we’re looking for here is having the chain aligned with the biggest cog, when the derailleur is pushed all the way in. If your chain does not reach the lowest gear you need to unscrew the limiter screw anti-clockwise, if your chain is dropping off the cassette, screw clockwise. Again, do a bit at a time and check your work constantly, to make it easier to find the sweet spot.
The B-tension screw will adjust the preload on the derailleur spring. It is a bit more involved, as different manufacturers or even different components series within a manufacturer range will have different adjustment settings. We’ll recommend leaving this adjustment for your local bike shop.
CABLE TENSION ADJUSTMENT
It’s finally time to adjust the cable tension. This is what ensures the chain is correctly aligned with each cog, when selecting the corresponding gear.
We’ll start this adjustment on the highest gear, while spinning the pedals shift one gear down. The chain should quickly shift from the smallest cog to the second smallest. If the chain is jumping or hesitating to shift you probably need to increase the cable tension. We do that by twisting the derailleur barrel adjuster anti-clockwise. If your derailleur does not have a barrel adjuster, it’ll be on the right hand side shifter.
The opposite is also true. When shifting up a gear, the chain should crisply shift to the next smaller cog. If that doesn’t happen you would have to decrease the cable tension by twisting the barrel adjuster clockwise.
Perform small increments at a time and check the results after every adjustment. Return to the previous setting in case you’ve gone a bit too far.
And this is how you adjust your rear derailleur. Don’t forget to apply a bit of chain lube to the chain after finishing this process and you’ll be ready to rock!
For more fine adjustments guides, check out our Workshop Series. Make sure to enjoy your time maintaining your bike as much as you do riding it, and happy riding!
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