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  1. #1
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    Hope Derailleur = Heahdache!

    I know , i know, stupid newb, but i am having derailleur probs. any advice would be greatly appriciated.

    heres the deal, i attempted to adjust my rear derailleur, and it turned out pretty well. just a little prob with biggest rear cog skipping a gear when shifting to harder gear, and when adjusted by the barrel adjustment it works fine until continuing to up shift. when it gets near smallest cog does almost same prob as when on the biggest. and when adjusted it continues to flip flop back and forth.

    on the front derailleur, almost same prob. will not shift from middle gear ring to the smallest, the chain just grinds against guard. when adjusted by barrel adjust, it works but then screws up going from middle ring to largest.

    sorry for the dumb questions

  2. #2
    Hoosier
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    SS is like beer...its an acquired taste.

  3. #3
    Old man on a bike
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    Barrel adjusters work to a point, sometimes you need to pay attention to the high/low limits and the cable and/or housing as well. Hard to tell what your problems are due to the description being somewhat vague...the parktool links provided by keatan should help...
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  4. #4
    local trails rider
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    In the rear, a bent derailer hanger could cause what you describe: some of the gears a bit off, whatever you do with the barrel adjuster.

  5. #5
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    Sorry but kinda off topic question. What is so great about a single speed?

  6. #6
    local trails rider
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    Quote Originally Posted by siscoOGpimp
    Sorry but kinda off topic question. What is so great about a single speed?
    Slightly on topic..
    On a singlespeed bike you don't have problems with derailers, derailer hangers, gear cables or shifters...

  7. #7
    I like bacon... (clyde)
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    Your limits are too tight in all cases you described. Get a good cable tension as best as you can, then loosen your limits 1/8 of a turn at a time. In the rear, your jockey pulley (I think thats what its called) will almost always be slightly beyond the outer cogs in either limited position, ideally. Its not much, maybe only 1/4 the width of the cog (or, 3/4 overlap). Do some research on the links provided and let us know if you have any more questions.
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  8. #8
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    Also, dirty cables can cause some of the problems you mention and it's going to be difficult/impossible to get the derailleur adjustments right if your cables have too much drag.


    Most bikes have slotted cable stops on the frame. If you shift the chain to the big cog and leave the chain there then shift just the shifter without pedaling/moving the chain down to the smallest cog you should have enough slack in the cable to pull the housing out of the stops and slide the cable through the slot. Once you get the cable free you can slide the housing around, clean/lube the cable and check for friction/kinks, etc.

  9. #9
    R.I.P. DogFriend
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    Disclaimer: This is what works for me. It's best to download the factory installation document, but if those sort of documents make your eyes glaze over, then you could give this a try

    Rear Derailleur Adjustment:

    1) Shift the bike to the smallest cog (9th gear if it's a nine speed setup). Turn the cable adjuster on the shifter for the rear derailleur (right end of the handlebar) all the way in and then back it all one full turn. If you're using a Shimano derailleur with a cable adjuster where the cable enters the rear derailleur, do the same thing with that adjuster that you did with the one on the shifter.

    2) Loosen the cable nut on the rear derailleur and gently use a pair of pliers to pull the cable fairly snug (but no need to pull it super tight), and tighten the nut a little over half way tight (tight enough that it won't move when you shift while adjusting, but no so tight it will disfigure the cable in case you have to make an adjustment before you're finished).

    3) Shift the bike to 2nd gear and look at it from the rear of the bike. Use the cable adjuster (on the rear of the derailleur if it's a Shimano or at the shifter if using SRAM) to adjust the top pulley on the derailleur so it is lined up exactly with the 2nd to largest cog on the cassette. You use the adjuster on the rear derailleur for this step if using Shimano so that you save as much room at the shifter as possible for subsequent on-the-fly adjustments.

    4) On the rear derailleur, shift to the largest cog and look at the derailleur from behind. Use the limit screw on the back of the derailleur to adjust the derailleur so the top pulley wheel lines up exactly with the large cog when looking at it from behind. Shift down to the smallest cog and do the same using the other adjustment screw on the back of the derailleur.

    5) Again shift to 2nd gear and check the pulley alignment and then shift to the 8th cog and make sure it lines up well there too. Make any fine adjustments you can see are necessary.

    6) You are ready to test ride the bike. If it is not shifting smoothly, shift it to 2nd gear and look at it from behind. Hold up the rear of the bike and turn the pedal (it's easier if you have help doing this). You can also turn the bike upside down, but shift it first to 2nd gear so you don't have to do this with the handlebars on the ground. Watch the way the chain acts as you turn the pedals. If it jumps up toward the largest cog, turn the adjuster inward (tighten) one 'click' at a time until it stops jumping. If it is looking like it is trying to shift to a smaller cog, turn the adjuster as though to loosen it (this will in effect increase the cable length) until it stops trying to shift downward. Retest the bike by riding it. Repeat this step until it shifts perfectly.

  10. #10
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    I would like to build on what Jeff said:

    Before you get started I would suggest you ensure the shifter barrel adjustment is all the way in.

    After you set the lower limit on the derailleur pull the cable (w\ your hand not the shifter) all the way to find the outer limit.

    Once you have the limits set you can typically fine tune the setup with the barrel on the shifter.

    Anthony

  11. #11
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    So many things this could be that it's difficult to diagnose over the net - so many things that we don't know about your bike. Here are a few more possibilities:
    • Dirty or corroded cable.
    • Dirty, corroded, or worn pivots on the dérailleur.
    • Cheap dérailleur that just doesn't work.
    • Worn out cogs and/or chain.


    The best thing is to look at the Park website, or buy the Big Blue Book, or Zinn's book. The second best thing is to take it to the LBS.
    Whatever your hand finds to do, do it with all your might.... (Ecclesiastes 9:10)

  12. #12
    Doctor
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    Quote Originally Posted by perttime
    Slightly on topic..
    On a singlespeed bike you don't have problems with derailers, derailer hangers, gear cables or shifters...

    ..here we go..

    You swap all those problems for knee injuries and walking up hills you should be riding.


    jeff

  13. #13
    local trails rider
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    Quote Originally Posted by noodletips
    You swap all those problems for knee injuries and walking up hills you should be riding.
    (Definitely off topic)
    Works great for me where I usually ride. The spots that kill me SS kill me about as thoroughly on the gearie bike too. I have a history of knee problems too: no issues since I started SS.
    (/off topic)

  14. #14
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    No one said it, so I thought I'd check and eliminate a possible problem before you waste too much time.

    Are all the components, RD, FD, control set the originals, or the same series or compatible? Different derailleurs have different "pull response" and mixing components can cause problems similar to yours.

    If you've eliminated this possiblilty, check/adjust all as told by Jeff, to which I'll add one diagnostic.

    After upshifting (towards smaller cog) to any gear, if the trim is off, try plucking the wire from the frame (hard) where it runs bare, (like along the down tube). If after a pluck and release the errant RD now trims correctly, your problem is cable/housing friction somewhere along the line.

    Cable binding is extremely common in MTB since they're used in dirty wet environments and crud wicks into the housings and noodles. It's also a problem in cold weather if someone greased the cables and the grease stiffened with the cold.
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    The key to solving any problem is to understand and address the underlying cause.

  15. #15
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    thanx guys for all the input!

    as for the cables being worn out, i dont think it should be an issue. i have the motobecane fantom trail, and is only few months old. It has shimano long cage rear derailleur, and shimano front derailleur. it does seem the chain may be a little more loose than it was brand new, but not sure if loose enough to cause this problem.

    the bike has only hit the trails about 4 times, and the rest is just riding downed light poles without much shifting.

    in Mississippi the weather has been from 70's to 30's from week to week, and i have noticed a difference in performance according to temperature.

    I have already set the limits on the rear, and still having same prob. have inspected the cable and appears to be okay.

    cant get the front derailleur to adjust at all. i can get it to set b/w two of the gears, but when adjusted for all three one of them ends up screwy.

  16. #16
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    If it's temperature related, it's probably because someone greased the cables (housings).
    The grease stiffens when cold and the light action spring of the derailleur doesn't pull the cable all the way down when shifting in the slack direction. It's not a problem when you pull the cable because you're stronger than that spring.

    Next time it acts up in the cold, try tweaking the exposed cable section and seeing if that changes the trim. If so, now you know why. Disassemble the cables and housings, flush the goo out with light oil or mild solvent and reassemble with only a light coating of thin oil.

    I ran a Campy service center for a number of years and every November would get a flurry of calls about sudden shifting problems for this very reason. It was so common, I almost got to the point of using a prerecorded message to deal with it. If.....push 6.

    BTW- don't go nuts trying to trim the FD until you know the cables run free.
    fb
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    The key to solving any problem is to understand and address the underlying cause.

  17. #17
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    Quote Originally Posted by jdr6031
    thanx guys for all the input!

    as for the cables being worn out, i dont think it should be an issue. i have the motobecane fantom trail, and is only few months old. It has shimano long cage rear derailleur, and shimano front derailleur. it does seem the chain may be a little more loose than it was brand new, but not sure if loose enough to cause this problem.

    the bike has only hit the trails about 4 times, and the rest is just riding downed light poles without much shifting.

    in Mississippi the weather has been from 70's to 30's from week to week, and i have noticed a difference in performance according to temperature.

    I have already set the limits on the rear, and still having same prob. have inspected the cable and appears to be okay.

    cant get the front derailleur to adjust at all. i can get it to set b/w two of the gears, but when adjusted for all three one of them ends up screwy.
    Here is my front derailleur adjustment method:

    Front Derailleur Adjustment:

    Before starting, make sure the FD (front derailleur) is aligned with the chainrings from front to back and that the height is set correctly so the chain 'cage' is at 2mm above the largest chainring when it is shifted to the #3 position. New front derailleurs come with a plastic spacer that holds the FD in the right spot so you can mount it correctly before you ever connect a cable. You can usually find something to stick in there to do the same thing. Once the FD is mounted correctly, remove this spacer and continue... If the derailleur is already mounted and has worked correctly in the past, you can skip this step and only refer back to it if you can't get it to work after the steps below.

    1) Just as with the RD adjustment, turn the cable adjuster on the front shifter all the way in and then back it out one full turn.

    2) Adjust the shifter to #1 on the shift control.

    3) If the shift cable is connected, make sure the cable is not real tight (taut) at this point. You can check this anywhere the cable is exposed from the housing. If it is taut, loosen the cable hold-down nut and disconnect the cable.

    4) Shift the rear derailleur so the chain is on the largest cog (1st gear). Using the limit screw that adjusts the lower limit (that keeps the chain from falling off the smallest chainring - this is usually the screw toward the outside of the derailleur, but not always), adjust it so the inside of the 'cage' barely touches the chain and then back it off just barely enough until it no longer touches the chain.

    5) Reconnect the front derailleur cable in the same manner as you did the rear one but with just a bit more slack. Not a lot, but it should feel just a bit 'loose'.

    6) Place the shifter in the #2 position and turn the pedal cranks. If the chain does not shift to the middle ring, move the chain to it by hand.

    7) Using the cable adjuster on the shifter, turn it one way or the other to move the cage so it just touches the chain and again the other way just far enough that it no longer touches the chain.

    8 ) While turning the pedal cranks, shift the front derailleur to the #3 position. It should shift there on it's own.

    9) Shift the rear derailleur to 9th gear. If the shifter will not move to the number 9 position, turn the other limit screw (the one you didn't use earlier) until it will.

    10) Making sure the chain is actually on the smallest cog on the rear cassette, use the same limit screw referred to in Step #8 to adjust the cage so it just touches the chain and then back it off just enough until it no longer touches the chain.

    11) Hold up the rear of the bike (or put it in a stand if you have one). Turn the cranks and see if the bike shifts OK from the largest chainring to the middle chainring and back to the largest chainring. If it does, shift the rear derailleur to the largest rear cog and check to see if you can shift from the largest chainring (in front) to the middle chainring.

    If it does not shift from the largest chainring to the middle chainring, turn the cable adjuster on the shifter inward until it does. If you have left enough slack in the cable as instructed in Step #5, you shouldn't run out of adjustment room. If not, you may have to shift down to #1 position on the front shifter, turn the cable adjuster all the way in and then back out one full turn, loosen the nut, give the cable a bit more slack than you did before and return to the beginning of Step #11.

    If it does not shift from the middle chainring up to the largest chainring, turn the cable adjuster outward (loosen) until it does (while turning the pedal cranks of course).

    12) While turning the cranks, shift the FD to the #1 position. If it does not satisfactorily shift to the smallest chainring, use the limit screw used in Step #4 to move the cage over toward the frame until it will shift to the smallest chainring while turning the cranks. Do this adjustments in 1/8 turns of the screw or less. If you go too far, it may throw the chain too far resulting in the dreaded 'chainsuck'.

    From here, you may need small fine tuning adjustments, but this should get you very close if not on the money.
    ==================

    Hope that helps!

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