front derailleur
I'm having front derailleur rubbing , on my trek fx 3, particularly when i'm in the 7/8/9 smaller cogs in the back and bigger cog in the front (46/30)..
what is the easiest way to adjust this, without digging my self into a bigger issue..i saw some tutorials online, and i notice that there is h screw and L screw on the front deraileur.. Which one should i adjust ? Will adjustments of front derailleur require adjustments of rear derailleur? |
I think the H screw will adjust the outward swing. Be sure to go a little at a time. You should be able to see the derailleur cage move as you adjust it if the cage is against the limit screw. Too much and it may rub the inside of the cage.
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what is the easiest way to adjust this, without digging my self into a bigger issue If this is a Shimano DR then I'd recommend you get the DM for it from the Shimano tech doc site and make certain everything about it is installed and set up correctly. Watch the videos too. ParkTool makes videos that I'd trust. Some youtubers have no clue but sound convincing. |
You need to watch a lot of videos and make sure you completely understand what you are doing. It is very simple, but if you don't get all the pieces straight in your head you could end up with hours of frustration.
The "H" screw adjusts the high end of the derailleur .... the outward swing. Loosening it (screwing it out) lets the derailleur swing farther out. Go too far, and the chain falls off the chain ring. Not far enough, the chain rubs, or won't even shift to the large ring from the small. The "L" screw controls the low range, how far the front derailleur swings inward. Again, too much and the chain drops off on the inside, too little and the chain rubs while on the largest cogs. Up Front: You want to start with your derailleur cable loose, the barrel adjusters about 1/4 out---some bikes don't have a front barrel adjuster, I guess--and the front derailleur in low with the chain in the middle of the cassette in back.. Pull the cable until it is just snug and tighten it down. Then use the L screw to pretty much center the derailleur and chain over the small chain ring. Hit the shift lever which should tighten the cable and swing the derailleur up and out. Try to center the chain over the large ring with the H limit screw. You might need to come a small amount in or out with either screw --just make Small changes to the limit screws. There is also a "Trim" adjustment on some shift levers, which fine-tunes the derailleur to compensate for the chain angle at the far ends of the cassette. I will find the directions I have, give me a minute .... Ugh ... my notes are "Low trim ---- Small ring Big cog adjust for clearance. High trim---Big ring big cog, clear, adjust with cable." So .... on some brifters there are four distinct lever positions, low trim, low, high trim, and high. The trim positions are generally much lighter shifts---sort of a half click. I assume my notes mean that to set the low trim, you shift all the way down---hit the front lever five or six times just to be sure. Put the chain on the small ring and biggest cog (lowest gear) and set the limit screw ("L" screw") so that the inner side of the front cage is about a millimeter or a little less from the chain. To set the high trim, hit the lever upwards (On a Shimano brifter, the Up lever) five or six times to be absolutely sure you are all the way in high--then shift Down that half click. The derailleur should move minutely but not drop the chain onto the small cog. Shift to the biggest cog in back, and use the barrel adjuster to loosen (screw In (in Very small amounts---1/16th of turn at a time,) or tighten (screw Out in very small amounts) until t again there is about a millimeter of clearance between the inner cage wall and the chain. If all that is wrong, sorry. I already told you to watch videos- (don't Ever listen to me.) Park Tools might be the best, but get a few different takes on it. Again, don't Ever listen to me. |
If you are talking about an issue with the large chainring and the “smallest” cassette cogs (positions 1, 2, 3) my first thought is the FD cable has too much slack.
This does assume that everything worked fine at one time. Shift to the small chainring and see how taut or loose the cable feels. If there is slack in the cable, simple turn the cable adjuster, if there is one on downtube/head tube, to remove the slack. This may not solve other adjustment issues, but slack in the cable will not move the FD cage over enough. With chainring ramps and pins, it may still get the chain onto the large chainring instead of falling back down to the small chainring. John |
Originally Posted by Rdmonster69
(Post 22239490)
I think the H screw will adjust the outward swing. Be sure to go a little at a time. You should be able to see the derailleur cage move as you adjust it if the cage is against the limit screw. Too much and it may rub the inside of the cage.
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Originally Posted by Rdmonster69
(Post 22239490)
I think the H screw will adjust the outward swing. Be sure to go a little at a time. You should be able to see the derailleur cage move as you adjust it if the cage is against the limit screw. Too much and it may rub the inside of the cage.
99.999% of derailer problems are due to cable tension. The other 0.001% of the problem is likely due maladjustment of the derailer but only about 1 in 100,000 of those is due to improperly adjusted limit screws…unless someone grabbed a screwdriver! |
Originally Posted by Awesomeguy
(Post 22239480)
I'm having front derailleur rubbing , on my trek fx 3, particularly when i'm in the 7/8/9 smaller cogs in the back and bigger cog in the front (46/30)..
what is the easiest way to adjust this, without digging my self into a bigger issue..i saw some tutorials online, and i notice that there is h screw and L screw on the front deraileur.. Which one should i adjust ? Will adjustments of front derailleur require adjustments of rear derailleur? Stop up your ears, brave Odysseus! Many a budding bicycle mechanic has been dashed on the rocks by the Siren song of the limit screws! Assuming that your bike has worked correctly at some point and that someone else didn’t fall to the limits screws Siren song, your problem is with the cables. Perhaps the easiest way to test for a cable issue is to shift into the large cog and push on the shift lever. If the derailer moves further outward when you push on the shift lever, your cable needs to be tightened. If the derailer doesn’t move, you might have a limit screw issue but, in my considerable experience, that is a very rare event. If your cable is loose (most likely), you also might check the anchor bolt on the derailer. If it isn’t tight enough, the cable can slip and that can cause rubs too. |
Originally Posted by Awesomeguy
(Post 22239480)
I'm having front derailleur rubbing , on my trek fx 3, particularly when i'm in the 7/8/9 smaller cogs in the back and bigger cog in the front (46/30)..
what is the easiest way to adjust this, without digging my self into a bigger issue..i saw some tutorials online, and i notice that there is h screw and L screw on the front deraileur.. Which one should i adjust ? Will adjustments of front derailleur require adjustments of rear derailleur? If you don't know how to adjust the derailleur you should watch a bunch of good YT videos as others have suggested. I would also suggest starting from the very beginning...reset the whole thing. This way you'll have a better understanding of the 'hows and whys'. 1) Put the bike in a work stand. 2) Undo the cable from the derailleur anchor bolt. 3) Screw the barrel adjust at the shifter in all the way, then back out 1 turn. 4) Shift the bike into the largest cog in the back. 5) Make sure the outer derailleur plate is parallel to the chainrings. 6) Adjust the low limit so there is 1-2mm between the chain and the inner cage plate. 7) Attach the cable, pull on it so it's snug. 8) Shift the rear to the small cog. 9) Shift the front to the large chainring (it's a chainring, not a cog). 10) Watch the derailleur as you make the shift, the cage should shift the chain up to the large ring and stop...the high limit controls this movement. If it goes too far the chain will come off the outside of the ring. If it doesn't go far enough it will not make the shift. You want the derailleur to shift up and stop. You don't want it to make the shift then move back at all. This is controlled by the barrel adjuster on the shifter. If the derailleur makes the shift but the chain goes back to the small ring when you stop pushing on the shift lever you have too much tension and need to screw in the barrel adjuster a bit. If the derailleur makes the shift but moves back a little when you stop pushing on the lever you need more tension. You want the same 1-2mm clearance between the chain and the outer plate. |
Originally Posted by cyccommute
(Post 22239665)
Yes, the high limit screw will allow for more outward swing…but it doesn’t “adjust” the outward swing. People get in trouble with derailers because they think the limit screws do something that they don’t do. Once set, the limit screws could (and probably should) be ground off. From that point forward, the only thing that controls movement of the derailer is the cable.
99.999% of derailer problems are due to cable tension. The other 0.001% of the problem is likely due maladjustment of the derailer but only about 1 in 100,000 of those is due to improperly adjusted limit screws…unless someone grabbed a screwdriver! Fun Fact: 78.327% of statistics are made up. |
Originally Posted by cxwrench
(Post 22239695)
To start this post should not be in GD, it should be in the proper section which is of course 'bicycle mechanics'.
If you don't know how to adjust the derailleur you should watch a bunch of good YT videos as others have suggested. I would also suggest starting from the very beginning...reset the whole thing. This way you'll have a better understanding of the 'hows and whys'. 1) Put the bike in a work stand. 2) Undo the cable from the derailleur anchor bolt. 3) Screw the barrel adjust at the shifter in all the way, then back out 1 turn. 4) Shift the bike into the largest cog in the back. 5) Make sure the outer derailleur plate is parallel to the chainrings. 6) Adjust the low limit so there is 1-2mm between the chain and the inner cage plate. 7) Attach the cable, pull on it so it's snug. 8) Shift the rear to the small cog. 9) Shift the front to the large chainring (it's a chainring, not a cog). 10) Watch the derailleur as you make the shift, the cage should shift the chain up to the large ring and stop...the high limit controls this movement. If it goes too far the chain will come off the outside of the ring. If it doesn't go far enough it will not make the shift. You want the derailleur to shift up and stop. You don't want it to make the shift then move back at all. This is controlled by the barrel adjuster on the shifter. If the derailleur makes the shift but the chain goes back to the small ring when you stop pushing on the shift lever you have too much tension and need to screw in the barrel adjuster a bit. If the derailleur makes the shift but moves back a little when you stop pushing on the lever you need more tension. You want the same 1-2mm clearance between the chain and the outer plate. |
Originally Posted by restlessswind
(Post 22239959)
Fun Fact: 78.327% of statistics are made up.
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Originally Posted by cxwrench
(Post 22239655)
You should not be giving advice on how to adjust derailleurs, you don't even know how things work.
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Originally Posted by cyccommute
(Post 22239665)
Yes, the high limit screw will allow for more outward swing…but it doesn’t “adjust” the outward swing. People get in trouble with derailers because they think the limit screws do something that they don’t do. Once set, the limit screws could (and probably should) be ground off. From that point forward, the only thing that controls movement of the derailer is the cable.
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Originally Posted by Rdmonster69
(Post 22240034)
Thanks internet police. I will stick to working on my own bikes like I have for the last 40 years. I have adjusted derailleurs pretty much like I described for quite some time with plenty of success. If you have a correction to my comment maybe put that in there instead of just acting like a ******.
Originally Posted by Rdmonster69
(Post 22239490)
I think the H screw will adjust the outward swing. Be sure to go a little at a time. You should be able to see the derailleur cage move as you adjust it if the cage is against the limit screw. Too much and it may rub the inside of the cage.
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Originally Posted by cyccommute
(Post 22240032)
Yes, is most cases. However, I’ve worked on over 15,000 bikes with the greatest complaint on almost all of them being something along the lines of “the shifting doesn’t work”. Most people are surprised at how quickly I can make their bikes work properly without picking up a single tool. I’ve even picked up the name “derailer whisper” at my co-op.
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Originally Posted by cxwrench
(Post 22240132)
40 years of 'experience' and you "think the H screw will adjust the outward swing"? Please, stick to your own bikes. And, check my next post...complete, step-by-step instructions.
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Originally Posted by restlessswind
(Post 22240159)
WOW ! Relax man. This is a public forum, not your bike shop Mr. Manager
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Better not put the chain on backwards!:banned:
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Originally Posted by Rdmonster69
(Post 22240049)
My suggestion was inferring that the high limit screw was preventing a derailleur with a properly adjusted cable from providing the proper movement.
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Originally Posted by cxwrench
(Post 22240168)
No thanks, I'll continue to call people out on bad advice when I see fit.
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Seems some need to work on their wrenching skills, others their people skills.
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I know that front derailleur problems are common, but is it beneficial in this regard if you have higher end components, like deore or shimano 105 etc.??
I have Acera front derailleur and Alivio rear derailleur, rest of the bike is acera. I know 1X is a trend right now, but i think i like 2X most since you wide range of cadence\gear options. |
Acera and Alivio are not great groups .... but they are serviceable. They will do the job. In my experience the lower-end Shimano stuff flexes more, and seems to stay adjusted less, than the good stuff. But ... it all works.
I have an Acera RD on my Cannondale tourer, and a Claris triple FD ..... and I have zero complaints. (Claris is comparable to Acero, just road vs MTB-oriented.) Set them up right, ride them, and if they need a tweak now and then, an 1/8 turn on the barrel adjuster usually does it. The important thing with derailleurs is having a clue how to set them up. I don't, so I visited Park Tools' website and both printed the text and copied the video links for their instructions. That, plus a couple other YouTube videos, made setting up, adjusting, and indexing seem as simple as it actually is. I sometimes have a hard time following seemingly complex instructions because I try to remember everything. Some stuff just seems daunting. I just learn step-buy-step, make sure I understand each step, and then after I am sure I know Step One, I move on. Eventually the stuff I thought was super-complicated and difficult, is commonplace and simple. My advice would be, Don't just go in there turning screws and barrel adjusters randomly, to see what happens. Cable tension and limit screws affect each other---if the cable isn't pulling the derailleur all the way to the limit, then you can turn the screw until it falls out .... and if the derailleur hits the inner (L) screw turning the barrel adjuster won't do a thing---but then, when you finally get the limit screw properly adjusted, the cable will be an issue because you adjusted it for a different range of motion. And with the rear derailleur, if you have removed the "dork disc" on your rear hub, and if you set the rear Low limit screw too far out, your derailleur will dive into your spokes, often ripping the derailleur off the frame, bending the derailleur hanger, and maybe breaking a couple spokes. Guaranteed highlight of your day. Go slowly through the instructions. They are Not complicated, taken in small pieces. Think about how complex the instructions for tying and double-knotting shoelaces would be, printed out ..... adjusting your derailleurs and cables is a lot simpler than that. |
Originally Posted by Awesomeguy
(Post 22240972)
I know that front derailleur problems are common, but is it beneficial in this regard if you have higher end components, like deore or shimano 105 etc.??
I have Acera front derailleur and Alivio rear derailleur, rest of the bike is acera. I know 1X is a trend right now, but i think i like 2X most since you wide range of cadence\gear options. Try cable adjustment before you replace the derailer. If the cable adjustment doesn’t work, try tuning the limit screws. |
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