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  1. #1
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    slipping gears after cassette and chain replacement

    I was experiencing some major slipping on my Giant Iguana that I use to ride to school, I had my chain and cassette changed and adjusted at REI I feel like they did a poor job. I still have slipping deff not as much but still get some. I don't get why I have slipping in the back of my bike even after a drive chain replacement. Everything looks good it is just kinda nasty and it happens on all of my chainrings however only on my lower(smaller) rear cassette gears. so say I am in my top chain ring(biggest) and lowest gear on the cassette(smallest) peddle hard and I hear a metal to metal sound from behind me, and feel my crank slipping. it seams to happen more when I am going over a bump or quickly accelerating. do you guys have any ideas of what it could be? are there some sram cassettes that don't work with a Shimano HG-53 9-Speed Chain? my new cassette is a SRAM PG-980 9-Speed Cassette. is it my derailleur?
    Last edited by immetro; 03-27-2012 at 01:13 PM.

  2. #2
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    It could be the cage spring on your derailleur is failing or slipping out of its detent on the cage.

  3. #3
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    in that case it would it be worth it to replace the whole derailleur? or can I simply replace the spring... I don't think derailleur are too expensive.

  4. #4
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    If you didn't replace the chain rings and they are heavily worn the chain could be riding up them - try and watch with the bike on a stand or looking down while pedaling along - see if the chain is riding up the chain ring a little while pedaling. This would cause chain suck and could feel like slipping. It's can happen if the rings are very worn and you put on a new chain.

  5. #5
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    I have similar problem of chain slippage in higher rear gears when a lot of pressure is applied (my rear cassette looks pretty good and so does the chain). I just orderdered a blackspire chain tensioner to see what happens.

  6. #6
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    I've had this problem. The chain isn't "slipping", it's getting stuck on the rear cassette and suddenly popping free, giving you that slipping foward feeling. If you just replaced the chain without replacing the cassette you've found your problem. Also keep your chain well lubed.
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  7. #7
    Yes, that's fonetic
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    Could be slipping on the chainrings (front). Sometimes it seems like it's slipping on the cassette but really skipping up front. Could also be that the chain is way too long, with a new chain you usually have to remove a few links...something the REI mechanic may be clueless about. If you shift into the big ring on the cassette and big ring on the crankset your derailleur should be pretty stretched and if you go small/small there shouldn't be significant sag in the chain. I doubt it's the derailleur.

  8. #8
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    Doubt derailleur is causing slips. Derailleur just shifts gears and keeps pulleys in place while they spin. It has basically no impact when you step on the pedals, as entire energy from front chain ring (cranks) is transferred to cassette.

    Try this: let one of your friends apply brakes, and step on the pedal. You will notice that the top part of chain is tense, but as soon as chain curves behind cassette it is not tense anymore. You can poke it with finger, you will see.

    Reason your chain might be slipping:

    a) You bought (or they accidentally) installed wrong chain, 10 speed chain on 9 speed cassette does that.
    b) I did not understand clearly, did you change cassette too as well? Or you have old cassette? Old cassette + new chain = epic fail.
    c) Stuff is not lubed properly. Try cleaning everything with degreaser, and apply some good lube (Teflon dry).
    d) There is junk in your cassette, between rings. I had small branch lodged in there, which caused the chain not to fall into rings properly. Slipped like mad.
    e) Your front rings are worn out. It is really hard to know 100% where you slip, on front or on back.
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  9. #9
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    Chain rings.
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  10. #10
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    The OP states in his first sentence that he was having the issues both before and after installing the replacement parts.

    If it's definitely coming from the rear, I would first check rear derailleur adjustment and alignment. If that does not resolve your issue, I would then inspect the pawls on your rear hub. OP, if you're a bigger guy, you could be breaking or damaging pawls when the pedals are under heavy load.

  11. #11
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    Quote Originally Posted by whodaphuck View Post
    Could be slipping on the chainrings (front). Sometimes it seems like it's slipping on the cassette but really skipping up front. Could also be that the chain is way too long, with a new chain you usually have to remove a few links...something the REI mechanic may be clueless about. If you shift into the big ring on the cassette and big ring on the crankset your derailleur should be pretty stretched and if you go small/small there shouldn't be significant sag in the chain. I doubt it's the derailleur.
    This. Sounds like you need new front chainrings. REI has some great mechanics, but they also hire some meathead ones. This is a common error.
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  12. #12
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    Pawls...

    If the derailleur cogs are directly in line with the cassette, it can't skip on the cassette, with that many teeth, it cant skip, regardless of wear. (sort of) (I suppose it you are a massive beast with tree trunk thighs, maybe.)

    To work with drivetrain is really look at it, if it lines up, it works. Toss the mystery, choose math.
    Last edited by flyxaos; 03-28-2012 at 08:14 AM.

  13. #13
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    I chased this problem for a season once and it turned out to be chainline alignment issues. If the proper spacers weren't used for your bottom bracket install then you will definitely have those issues, ESPECIALLY when in the cross gears like you describe: large ring and smaller cogs = cross geared and you'll get some noise no matter what but chain shouldn't skip unless you have alignment issues. Check der alignment first as was mentioned - have to bring to a KNOWLEDGEABLE shop for that (REI is NOT a knowledgeable shop!) or buy the expensive tool yourself.

    Have FUN!

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  14. #14
    Yes, that's fonetic
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    To clarify, you CAN use a 10 speed chain on a 9 speed cassette, you just can't go the other way around. Pin to pin they're the same measurement, just skinnier (for the 10 sp.).
    Also, like Gman said this is an invaluable tool.
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  15. #15
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    Quote Originally Posted by Pau11y View Post
    Chain rings.
    +1.

    Had the same problem. Replaced the chain and cassette, but it wasn't until I replaced the rings that the problem went away.

    Expensive lesson for me to learn -- replace the chain when it's worn, before it wears down the rest of the drivetrain.

  16. #16
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    Like half man-half scab said, it may be the beginning of the end for your freehub.

  17. #17
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    There doesn't seem to be a shifting-issue so strike the derailleur. There doesn't seem to be a problem with "ghost-shifting" so alignment and derailleur-hanger isn't the problem. The rider is (hopefully ) not "cross-gearing" which would be large ring / large cogs or small ring / small cogs. There is no mention of free-wheel problems nor grinding noises that are characteristic of chipped/broken pawls....

    The OP does mention the "slipping" is evident during sudden acceleration and over bumps - both instances of chain-torque. The suspect is worn chain-ring(s). Instead of a clean 'U' -shaped pattern, the pattern looks like a first-graders attempt at drawing waves. Compare your rings to a new set and/or have a first-grader draw you a picture of the ocean...

  18. #18
    Yes, that's fonetic
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    "Shark finned" is the way I've always described it.

  19. #19
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    The chain ring is worn but i can still see the cogs poke through the chain and haven't seen it slip there yet... but I will try to do a chain ring replacement soon. The REI i went to had a good mechanic and just from looking at the alignment it is not the problem I usually do the bike maintenance myself(figured 5 bucks to intall a cassette was worth it) and have never had this happen in my 6 years of biking it's very odd. I am going to convert the bike to a 9 speed from a 27 speed soon hopefully that is how I have my competition bike I hope it's the chain ring that would be an easy replacement. I am not gear crossing I only used maybe 3 gears always on the large chain ring and never smaller then the first 3. umm as for being a big guy deff not I'm 140 pounds but I have huge thighs but I doubt I am breaking anything. I would be pretty proud of myself if I broke pawl but at 140 lbs I doubt it's happening.
    Last edited by immetro; 03-28-2012 at 04:10 PM.

  20. #20
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    Check your front chain ring could be badly worn or a few missing teeth, also could be the free hub.

  21. #21
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    Hi
    Since I am new and can't start a new thread, I am having a free hub slip really bad on an AC Chub hub vintage 1995. Now AC ( Adventure Components ) no longer make parts for this hub. Is it worth taking apart plus I cannot figure how to do it. The Axel only has one cone wrench fitting on the free hub side, fine but there is no allen key fitting on the other side of the axel. I can work on bikes but this hub has me stumped???? Any ideas....

  22. #22
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    Hopefully others may be able to have the simple fix that I had.

    I had pretty new chain rings (less than 250 miles on them) when I bent a gear in the rear cassette. I replaced the rear cassette and chain at the same time. Bottom line is that everything was new.

    I decided to do the work myself and bought a chain whip and tool for the cassette removal/installation. Everything went well and seemed to be right. Front and rear der. adjusted and shifted all gears smoothly.

    When under load in almost any gear combination I would get popping sounds accompanied with slipping... literally the pedal under my foot would slip. Read through several posts and found a mention about not tightening the cassette enough may cause this problem under heavy load. Sure enough I was able to tighten the cassette considerably, it even seem looser than the initial install.

    During my ride today I was able to hammer the pedals hard in a bunch of different gear combinations on a range of terrain and not one single slip!!

    What finally prompted me to look into what was going on is that I took a fall once when the cassette slipped. I was mashing the pedals hard and then suddenly POP! and my foot instantly felt no resistance and I went down:


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