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Suspicious front derailleur behaviour

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Suspicious front derailleur behaviour

Old 08-07-21, 01:05 PM
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IcePea379
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Suspicious front derailleur behaviour

Hello, bike forums user, for 2 days I tried to adjust the front derailleur of my mom's new bicycle with my dad. The best guide for this that we found was the Park Tool's video about "How to Adjust the Front Derailleur".
The process was pretty straightforward before we finished adjusting the L-limit screw. For the H-limit screw, the process is to put the biggest cog in the front, and the smallest at the rear. But every time when we tried to do so, the derailleur was shifting over the 2nd cog, that was because of high barrel tension, but every time when we were making the cable slacker, the problem was the same, and turning more resulted in running out of turns. Now, me and my dad thought to make the cable so that it will have more space to go in, and the process was like this: put the smallest cog in the front, and the largest at the rear, disconnect the cable from the derailleur, turn all the way out the barrel adjuster counter-clockwise, and then all the way back in clockwise, and then turning 3(before this it was just 2) revelations counter-clockwise, and then connect the cable back. But when shifting, the problem was the same, and turning clockwise all the way in resulted in the same problem. This was our headache for 2 days! My mom's new bicycle uses the Shimano Tourney TZ. Please, if somebody knows the problem and the fix, please, just please tell it to me. I intuitively thought that the problem might be in shifting levers, and the dysfunction could be that they move the cable too much, and the "pre-determined" levels are not set properly. So please, if you why this problem is occurring, please, tell it to me, I am tired and my dad is tired, I am pissed off, and he is too

A few more details: We managed a few times to put the chain on the 2nd, but when we did that the chain was rubbing pretty heavily with the derailleur chasing, when we tried to slacken off the cable(so that the derailleur will go inward) we ran out of turns, no matter how much space the barrel adjuster had. Plus that when attempting to pull the shifting lever up so that the number on the shifting levers will match the cog number, we were always unable to do it. By turning counter-clockwise the H-limit screw, we managed to pull the chain on the 3rd cog and the shifting levers to show 3, but there was still heavy chain rub, trying to slacken off the cable resulted, AGAIN, in running out of turns, n matter how much space we left reserve.

Last edited by IcePea379; 08-07-21 at 01:57 PM. Reason: A few more details
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Old 08-07-21, 01:22 PM
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Crankycrank
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Originally Posted by IcePea379 View Post
The process was pretty straightforward before we finished adjusting the L-limit screw. For the H-limit screw, the process is to put the biggest cog in the front, and the smallest at the rear. But every time when we tried to do so, the derailleur was shifting over the 2nd cog, that was because of high barrel tension, but every time when we were making the cable slacker, the problem was the same, and turning more resulted in running out of turns.
First of all refer to the "front cogs" as "chainrings" as this just makes it easier to follow along when describing the problem. What you're describing is the function of the H-limit screw. This is what limits how far the derailleur can move to the outside of the chainrings and the same for the L-limit screw for the inside. Set these first and then the cable tension which is independent of the derailleur limits. Turn the H-limit screw in 1/4 turn at a time until the chain still shifts onto the large chainring but does not fall off (or "drop" to) the outer side. You may need to fine tune the limit screw adjustments when riding the first time.
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Old 08-07-21, 01:54 PM
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Did that, but the problem is, even if the chain doesn't fall off the chainring, there is still rubbing between the chain and the derailleur, turning clockwise the barrel adjuster won't help me because i run out of turns. I described this in the "A few more details" section of the post.

Last edited by IcePea379; 08-07-21 at 01:58 PM.
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Old 08-07-21, 02:04 PM
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Be sure the cable is attached to the derailleur correctly. There may be a small tab at the pinch bolt pointing toward the seat tube. The cable should be routed around that tab, away from the center of the pinch bolt. Incorrect routing of the cable between the tab and the bolt is a fairly common mistake, and it will completely mess up the shift pull ratio. It will pull too far per shifter click, and will be harder to shift.

You didn't mention if this is a double or triple crankset. I assume it's a triple.

And if you're reconnecting the cable often, take care that you don't overtighten the bolt and fray the cable.
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Old 08-07-21, 02:29 PM
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If you're turning the barrel adjuster clockwise (making the cable longer or 'less tension) and not also adjusting the low limit nothing is going to change. If the chain is rubbing the derailleur in the small ring and the large cog you have to adjust the low limit as well as reduce 'tension'. That's what limit screws do...they 'limit' derailleur movement.
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Old 08-07-21, 03:12 PM
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...if the bicycle is new, and the two of you have already spent two days trying to figure it out, I would respectfully suggest you take it somewhere, probably the place you bought the bike. If not there, some other professional shop nearby.

The problem with trying to figure out what is wrong over the internet is that you, as a beginner at this, have trouble explaining it. I, as someone who has worked on stuff like this for a while now, know how to do it, and there are several things that might be happening. But I can't explain them to you well enough that you will understand, especially if there really is something going on that is not routine.

FWIW, Shimano Tourney is not the best stuff they make, but it ought to work. On a new bicycle, unless something is bent, it should have been more or less working right out of the box, and if not then, surely after whoever unboxed and assemble it checked shifting and braking function. But i really think you've suffered enough. It's entirely possible someone with more experience could do this in ten minutes.
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Old 08-07-21, 03:45 PM
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Originally Posted by 3alarmer View Post
.
...if the bicycle is new, and the two of you have already spent two days trying to figure it out, I would respectfully suggest you take it somewhere, probably the place you bought the bike. If not there, some other professional shop nearby.

The problem with trying to figure out what is wrong over the internet is that you, as a beginner at this, have trouble explaining it. I, as someone who has worked on stuff like this for a while now, know how to do it, and there are several things that might be happening. But I can't explain them to you well enough that you will understand, especially if there really is something going on that is not routine.

FWIW, Shimano Tourney is not the best stuff they make, but it ought to work. On a new bicycle, unless something is bent, it should have been more or less working right out of the box, and if not then, surely after whoever unboxed and assemble it checked shifting and braking function. But i really think you've suffered enough. It's entirely possible someone with more experience could do this in ten minutes.
The place the bike was bought probably does not have mechanics there. It was probably a Wally Mart purchase more than likely and they can barely put the bikes together let alone fix the problems they created. Heavily agreed on taking it to a professional, any new bike like that should be checked over by a professional unless you are knowledgeable about putting things together properly and tuning them which is the struggle here with the OP.
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Old 08-07-21, 05:07 PM
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The problem here is that the OP doesn't actually tell us what bicycle they are dealing with and where they bought it. If purchased from a bike shop, the OP can go back and ask that the shop correct the problem. If not, then the OP might be well served by taking the bike to a shop that repairs bikes to have the initial setup done properly. Limit screws can be the cause of the most catastrophic mechanical mechanical failures if the bike owner doesn't understand what they are for. they should almost never be touched unless the rear or front derailleur cannot shift to the lowest or highest gear. If a new bicycle doesn't shift properly it should be returned to the retailer, either for adjustment if the shop does repairs or for replacement if they don't
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Old 08-09-21, 08:14 AM
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alcjphil Great advice. Even if the bike came from X-Mart, unless they have none left in the store,. if you return the bike and say it's not working they will often just give you a new one in hopes that their *ehem* creative assembly techniques got one right purely by luck.
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Old 08-09-21, 09:05 AM
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Finally a valid response, I don't quite understand what you are referring to as a "tab"(not a native English speaker), but yesterday, until 3 am my dad was "playing", I trying to find the issue, and somehow magically worked. He said that the problem was that we were overthighting the cable at that caused the issue, anyway thanks.
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Old 08-09-21, 09:19 AM
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Also, I forgot to mention the rubbing was produced by the inner side of the derailleur. The problem was by overtightening the cable, and such, when the shift levers were set to the 2nd or 3rd chain wheel, the tension was too high, resulting in pushing the derailleur too far outward and resulting in chain rub.
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