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How to Adjust a Rear Derailleur – Limit Screws & Indexing

How to Adjust a Rear Derailleur – Limit Screws & Indexing


The most common question we get is
“how do I fix my shifting?” Maybe it’s not reaching all the gears,
or maybe it’s making all sorts of noises. Whatever the issue, and regardless of the make or model, this video on mechanical
rear derailleur adjustment will help you dial in your shifting
for optimal performance. Calvin Jones here, Park Tool Company. We hope this video will give you a
whole new outlook on your bike shifting. And before we begin, here’s a quick overview
of the components and procedures. The rear derailleur is the mechanism
that shifts the chain at the rear cogs. The derailleur is connected to the shifter
by a cable that passes through housing. Bikes commonly use an index shifter that moves the cable
in small predetermined increments with each click. Inside the derailleur body is a spring
that constantly pulls the derailleur outward. And our cable is constantly holding against that spring
in various shift positions. Derailleurs are fitted with limit screws that stop the derailleur
from moving too far inward and too far outward. Here we can actually see the limit screws
stopping the linkage at each end. The function of limit screws is to prevent the chain
from going into the spokes or into the frame. Our first procedure will be to set the H limit screw
and after that we’ll move on to indexing. Indexing is the process of
lining up our guide pulley with the cogs, so that each shift lines up with each cog. The barrel adjuster – located here or up at the shifter – allows us to move the shift increments as shown. After indexing, we’ll dial in our other limit screw. Then we’ll check our B screw adjustment –
and we’ll explain more on that later. For now, grab your tools – which are a screwdriver
or hex wrench for the limit screws – and a repair stand for some way to hold your bike up
so we can pedal and check those adjustments. Let’s get started. Now we’ll walk through the H limit screw adjustment. Our goal will be to dial it in as close as possible
to that inward cog. Sometimes the limit screws are unmarked, and we’ll
show you how to identify which is which a little later. We begin with the visual check of the
derailleur hanger, and if it’s clearly bent, things are not going to work well, and you should watch this other video on hanger alignment. If the bike has multiple front chainrings,
shift the front derailleur to the largest. Shift the rear derailleur to the smallest cog. Even if you’re already on the smallest cog, keep clicking until there are no more clicks. This make certain our shifter is fully actuated outward. If the change does not shift to the smallest cog, It’s likely being stopped either by the
limit screw or the shift position. First, turn the H limit screw
counterclockwise a few turns. Pedal and see if it makes the shift outward. If it’s not shifting outward, turn the
barrel adjuster clockwise a few rotations. Pedal to see if it shifts. so now everyone is on the smallest cog and we have no more clicks at our shifter. Now, even if you just did this, turn the
barrel adjuster clockwise a couple of turns. If there’s a barrel adjuster located at the shifter,
it performs the exact same function. Turning either one clockwise a couple of turns
add slack to the cable and this keeps us from confusing our shift position
with our limit screw settings. People often get those two things confused,
so here’s a quick explanation. We’re currently on the outermost shift position,
and even if things look lined up, the limit screw might be set to stop the derailleur
here, here, or it might be correct. We won’t know until we take our shifting position out of the equation. There are many ways to do this,
but easiest is to turn the barrel adjuster clockwise. We remember this moves the shifting positions collectively outward. Now we’ll be able to set our limit screw setting
without getting it confused with our shift position. We’re now ready to dial in the H screw. If you can’t tell which limit screw is the H screw, pick one and turn it in and out
while watching the derailleur. If the derailleur does not move, try the other one. The H limit screw will cause some motion. We’re going to find the correct setting
by purposely making it too tight – then we’ll back it out slightly until it’s just right. So grab your screwdriver and
tighten the H screw a half turn. Now, instead of only seeing if it’s too tight, we’re also going to listen for
excessive noise while pedaling. And if the front derailleur is making noise,
do your best to ignore it for now or find the fix in this other video. Back on the rear cogs,
we hear normal noise for this bike, which tells us our limit screw is not yet too tight. We tighten the screw again a half a turn. Now we hear excessive noise and we’ll double check that it’s coming from the
chain rubbing against the next inboard cog. If so, the limit screw is too tight,
which is what we want for now. By the way, this doesn’t damage your drivetrain at all. In some cases, an overly tight limit screw can cause a shift to the next cog. Back out this limit screw until it shifts back
and creates excessive noise. Once we hear the excessive noise, we begin to loosen
a quarter turn at a time until the noise is gone. If there are two settings that seem equally quiet, go with the tighter of the two settings. The H limit is now set. Now, we’ll turn the barrel adjuster
counterclockwise a couple of turns. We’re getting it back approximately to where it was – and don’t worry, it doesn’t need to be precise just yet. As for the other limit screw – the L limit – we will wait to adjust it until
after the indexing is set. Earlier, we explained that the process of indexing
is to line up the guide pulley with the cogs so each incremental shift… lines up with each cog. Again, the barrel adjuster allows us to make these adjustments A quick note is that there is a
range of acceptable adjustment, meaning there may be more than one barrel adjuster position that results in good shifting performance. If there are two front chainrings,
stay on the largest. If there are three front chainrings,
shift to the middle. On the rear, we start on the smallest cog. Pedaling at a normal riding cadence,
shift the rear lever only one index click – not more than one click. Note that some shifters are designed to click
multiple times with one push on the lever so push the lever slightly until you hear one click. We need this one click to shift one and only one gear. if the chain did not make it to the next gear, return the shift lever to the outermost click. turn the barrel adjuster one full turn counterclockwise. Try the shift again. Repeat until it makes the shift. If you have unthreaded the barrel adjuster
so much that it has come out or nearly out, thread the barrel back in fully… and then out one or two turns. Make sure you’re on the furthest outward
shift position and the smallest cog. Then remove the slack from the cable at the pinch bolt. In this different scenario,
one click at the lever shifts two sprockets. Shift back to the first cog and turn the barrel adjuster clockwise
and try the shift again. Now that our chain is on the second sprocket
from one click, the shifting can be fine-tuned. What we’re going to do is purposely turn
the barrel adjuster counterclockwise until we’re clearly out of the acceptable range,
and then slowly creep back in. Similar to the limit screw,
excessive noise is our indicator. If there’s not already excessive noise while pedaling, turn the barrel adjuster
counterclockwise until you hear it. Once we hear excessive noise, we know we are
outside the acceptable adjustment range. Now double check that the
source of the excessive noise is indeed from the chain striking the next inboard cog. Next turn the barrel adjuster clockwise a quarter turn and check again for the noise. Repeat until the noise is gone. While this is an adequate setting in this cog, we now need to check the other sprockets one at a time. Shift and listen at each position for any excessive noise. If you hear noise in any one cog,
turn the barrel adjuster clockwise a quarter turn. Test the shift to that cog again. Repeat and continue to check until we find the barrel adjustment that allows good shifting in every rear cog with the exception of the largest cog. The shift to the largest cog will be done later. Now: shift outward one cog at a time, again checking for
no excessive noise once the chain is on the cog However, if the shift is slow coming outward, that can be improved by another
quarter-turn clockwise at the adjuster. Our indexing is now properly set and it’s time to move to the L limit screw adjustment. Similar to the H screw setting,
we make the L screw too tight, then we back it out slightly until it is just right. This provides the most protection from the derailleur taking the chain past the largest cog and into the spokes. Shift the chain to the next-to-largest chainring in front. Shift to the second largest cog in the rear. Next, we need to figure out
where our limit screw is set. Is it already too tight? Is it far too loose? Shift to the largest cog to find out. If the chain does not make the shift, then the L crew is already too tight,
and that’s what we want for now. If the change shifts slowly to the largest cog, that’s also a symptom of too tight an L screw. If there’s excessive noise once on the largest cog, again the L screw is too tight,
and again, that’s what we want for now. However, if it makes an acceptable shift with no excessive noise, our L screw is not too tight. We turn the derailleur one click outward, Tighten the L screw a half a turn, and try the shift again. Repeat until there are symptoms. Now that the too-tight L screw is causing symptoms, we’ll loosen it incrementally until it’s correctly set. Loosen the L screw one quarter turn
and shift to see if the symptoms went away. Repeat until it shifts quickly and rides on the largest cog without excessive noise. The L limit is now set. As a check, put extra pressure on the shifter. Watch at the rear derailleur.
The cage should not move inward. Most derailleurs have some form of adjustment
for the spacing of the G pulley to the cogs. This spacing is controlled by the B screw –
B for body angle screw. This adjustment is checked when the chain is on the
smallest sprocket in front and the largest cog in back. The majority of road and mountain bike derailleurs
require a gap between five and six millimeters. Use a hex wrench to gauge this distance. There are some exceptions,
so consult the manufacturer’s specifications. But don’t get too hung up on this. If the bike is shifting well,
the B screw is adequately set. To increase this gap, tighten the B screw. To decrease the gap, loosen the B screw. If you made significant changes to the B screw,
double-check the indexing adjustment. Otherwise, you are done,
and your derailleur is properly adjusted. Those are the basic steps in adjusting the rear shifting. The bike should also be test ridden, because the stresses of riding on the drivetrain are different than when the bike is in a repair stand. If symptoms like slow shifting or excessive noise show up, follow the same guidelines as discussed in the video. You may need to change the barrel adjuster
or limit screw another quarter turn. Also, if you’ve gone through these steps
and something didn’t seem quite right, check out our video on advanced troubleshooting
and rear derailleur adjustment. Finally, be sure to check out this video for an overview of all our derailleur and shifting content. That’s it for shifting adjustment. If you found this helped you,
give it a thumbs up and share it with your friends. it really does help us provide content for you, and it keeps me locked up here in the studio. That’s it. We’ll see you on our next repair help video.

100 comments on “How to Adjust a Rear Derailleur – Limit Screws & Indexing

  1. So clearly explained and with the addition of the professional overlays / graphics this is such a big help! Thank you for producing this video!

  2. Thanks for posting this video. My new drivetrain was skipping gears in big chainring. Even replaced pulley wheels. No help. Using your guidance, I tightened the H limit screw. Problem solved.

  3. Calvin is a pro, not just in excellent knowledge of the topic but the delivery of the institution, excellent job.

  4. Лучшее видео на ютубе по настроке переключателя!!!
    Огромная благодарность автору, спасибо мэн.

  5. As almost everyone else has said, Calvin is just about perfect and this video covers the topic thoroughly but without all the mindless jabber that 'influencers' seem compelled to engage in. In addition, the graphics and sound of the chain brings home the point beautifully — sound is the key. Truly great video.

  6. Thank you for all these videos. They are a reason why I spent the extra money getting tools from ParkTool.

  7. Fantastic video. I love learning why I am turning certain knobs or tightening certain screws. The wife will be extremely happy once I fix her gears 🙂

  8. i have had a folding bike for about five years now, and about four of those years it wouldn't grab first or second gear and sounded like crap. i watched this video once and by the time it was done it grabbed all the gears and barely made any noise.

  9. Does anyone know how the numbers on the shifters correspond to the cogs on the back wheel? mine has numbers 1 to seven and that is the number of cogs in the back does number one correspond to the big cog or the small one? also for the front is one to three is from small cog to big cog or the opposite? he did not mention that in the video.I need to match the proper number to each cog.Thank you

  10. I was wondering if when building a bike, would it make more sense to adjust the front or rear derailleur first? I've been working at a bike shop for a few days now and adjusting this stuff is giving me the most trouble right now, and I've gone back and forth with the order. Thanks

  11. I like how did you explain it. With this tutorial I'm going troubleshoot all these symptoms on my bike. Thanks

  12. What if it shifts skips the second largest gear and jumps right into the largest when I shift only once? It also creates half gears when down shifting 🙁

  13. This video was great, thank you! But, after upgrading the cassette from an 11-36 to an 11-42 and downsizing the chainring to a 32t from 40, the b-screw needed to be tightened first to allow the derailleur to clear the granny gears before actually indexing those gears…

  14. Very good video, did 3 bikes with this one but I only got one working well (Shimano Deore XT). Ultegra and Deore doesn't work for me. Both have the same annoying symptoms, doesn't shift well up nor down. So it doesn't help if I turn the indexing to either of directions, always the one direction gets even worse. The cable and the housing seems to be ok. I cleaned the cable all the way and oiled it. Can the problem be still the cable or housing? They are a couple of years old, maybe 5000km driven. Derailleur hanger is on level.
    My humble opinion is that these adjusting mechanics are not very good. They should be improved. Your only option should not be worsen the other setting to make the other working better. I know it works when everything is new but should the adjustment work even when the product is a bit used? I hope the electrical gears will solve this for good. Thanks for the great vid anyway.

  15. I love these videos. Great public service and advertising for Park. I have fixed my brakes, chain, derailleur, and cassette with help from these videos. I have also spent over $400 on park tools. I will loyal to these guys forever.

  16. This video is perfect. The graphics are really helpful and the guy is awesome. I'd perform open heart surgery if he were walking me through it.

  17. Top quality, easy to understand video. Double thumbs up. Clear examples including trouble shooting. One of best instructive videos I’ve ever seen. Thank you.

  18. Possibly the best vid on YouTube. I made a detailed an outline following your steps exactly. Having never adjusted indexing before I was able to do it in less than 30 minutes. After a test ride I needed only a final minor tweak to the barrrel adjuster.

  19. When do you know to get a new rear derailleur? I recently went on a bike ride with a lot of hills and my derailleur hanger bent into the spokes. I also noticed that the barrel adjustment has a spring sticking out and looks to not be in place along with the derailleur plastic gears looking a bit chewed up. Should I also get a new derailleur if the adjustment barrel is broken?

  20. This video was SO helpful! It gave me a broader understanding of my Derailleur system as a whole and a great step-by-step tutorial on how to tune it up. I had watched other videos before this and almost given up on doing this myself because I was messing up my bike more than helping it. This video saved the day! And saved me from having to take my bike to a shop 🙂 Thanks!

  21. thanks park tool. I've followed the instruction and when I'm shifting down from the second large cog to the 3rd cog, there is a sound and is not shifting down, I've already turned the adjuster clockwise a couple quarter turns, and I cannot turn it anymore. what can I do?

  22. I can't believe there are any thumbs down for this video at all. That was a beautiful video man. Many thanks for it.

  23. Passing on the local bike shops that charge to much! ….learning to tune my own bike! Thanks Teacher! ….Great Videos!

  24. I used to work in a bike shop, this video is perfect, superb graphics, and I love the info telling you where to skip to if you are someone that doesn't want to learn the details, just wan'ts to sort it out… whoever edited this did a great job.

  25. At last, no music , no silly props . Thanks for a Great Clear video , you have saved me a right few Quid , Thankyou . Baz ( UK )

  26. Is it important for the bicycle to be upright, or can I set it upside down on the handle bars and seat to make the adjustments?

  27. Thanks Calvin. These videos are super helpful and well done. My go to source for bike repair/maintenance info.

  28. I have a new mountain bike and it started to shift errantly. I viewed several You Tube videos relating to my problem and none of them is a comprehensive and easy to understand as this video and its presenter. I will begin to do the suggested step-by-step procedures as indicated in the video and I have the confidence to ascertain what my shifting problem/s is or are. Well Done!

  29. Wow, amazing video. Managed to sort out my rear derailleur having spent an hour fiddling, trying to figure it out myself. Top stuff. Thanks!

  30. I am adding to all of the positive comments here. I've been frustrated for 30 years whenever my shifting would start to go awry. I would gradually get more and more frustrated until I finally would take it to the shop and get it fixed. But NOT TODAY! I brought my laptop out to the garage and watched the video while I worked on my bike (without a bike repair stand, but oh well). The instruction is SO good, and the graphics were very informative. Best I've ever seen, and it makes me want to seek out more Park videos to see what else I can do. I'm not sure how many shop guys like having to make videos, but be assured that this was very worth the time it took to make! Thank you!

  31. You and your videos are everything that is beautiful and right about the internet. LOL. I knew nothing about bike gears and bike caliper brakes, but with your help I was able to fix up a crappy beater mountain bike my friend gave me for free. Thank you.

  32. Thanks so much for the help! Very good instructions. Just be sure to follow them step by step. Play an instruction. Pause the video. Do what he says. Then play the next one.

    One tip: he briefly talks about the B-Screw adjustment at the end, but if that distance is way off, it will throw things off. My distance was really big, so I had to loosen the b-screw quite a bit. It does affect your shifting if the distance is to great. The smaller it is, the better the shifting.

    Cheers!

  33. Wow this is the only time I've seen it explained properly. Everyone else just tells me to mess with the cable lol

  34. Brilliant! I followed this tutorial step by step and got my Trek dialed in when the bike shop just couldn’t seem to get it right. My shifter flicks right through the cogs now when it used to drag and hang. The bike shop should watch this and educate themselves.

  35. OMG I love this instructional video. Was going to take two new e-bikes to our LBS to dial them in (brakes and shifters), but after watching this, I decided to spend my money on a Park Tool PRS-25 bike repair stand, and do the adjustments myself. Now I won't have to wait 1-2 weeks for our overworked LBS to get to our bikes!

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