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  1. #1
    over researcher
    Reputation: royta's Avatar
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    noisier drivetrain than what I'm used to

    Until recently, I was running:
    • M951 8sp integrated (brake/shift) shifters
    • M950 8sp (top 3 Ti) 12-32 cassette
    • SRAM PC-68 chain
    • M952 rear derailleur
    • M961 front derailleur
    • RF 8sp 22-32-44 chainrings
    I then swapped out to the following:
    • '08 X9 shifters
    • M770 11-34 cassette
    • CN-7701 chain
    • '08 X9 rear derailleur
    • same old front derailleur
    • RF 9sp 22-32-44 chainrings
    My rear drivetrain is noticeably louder when in the largest two or three cogs of the cassette, whether I'm in the inner or middle chainring. The first few miles of a ride are nice and quiet, as my chain is nice and slick from the night before's lubing. After 10 miles though, and I'm flat out annoyed. Why is this so much louder? Where can I place the blame? Is it because of the X9 jockey pullies, the M770 11-34 cassette, the CN-7701 chain? Everything seems to shift better when running more than the 1/4" space between cog and upper jocky pulley. I'm kind of frustrated and starting to wish I would have just gone with the '08 M770 shifters and a Shadow rear derailleur. My chainline doesn't seem out of wack. I measure 50mm from center of BB shell to center of middle ring.

    By the way, anybody who tells me I could have saved money by going with the '07 X9 combo from PricePoint needs to learn to shop from Larry.



    ETA - 11-34 not 12-34
    Last edited by royta; 07-30-2008 at 04:30 AM.

  2. #2
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    what kind of noise...grinding from unsmooth shifts, clicking and jumping when in gear, or just that faint metal on metal noise you sometimes hear when pedaling?

  3. #3
    over researcher
    Reputation: royta's Avatar
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    I wouldn't say it is a noise that indicates anything is functionally wrong. Yeah, I know, then why am I complaining? I guess because it is the first time I've heard this sound since I first started riding MTB's in 1993. Normally, my drivetrain is pure silence as long as my chain is lubed up. With the new setup, it is fine, as long as I am not in the largest two or three cogs. It is basically the sound of chain rolling along on gears. Although, there is noticeably more resistance on the top jockey pulley than on the bottom. This is when the derailleur is pulled up and the chain drooping away from the pulleys.

  4. #4
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    I know what you mean with the extra noise thing. I'm the same way, to a fault. I think I know the noise that you are talking about from your description. Other than lubing like a pornstar, make sure your chain is as short as it can be while still allowing you to hit every gear. I had a similar noise to this and noticed that my chain was about 1 link too long. It went away once I corrected the problem. I think the derailleur spring wasn't getting enough pull on it to tighen the chain properly in the high gears.

  5. #5
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    OP, your chainline is probably off by 1 or 2mm.

    Are the 8 speed chainrings thicker than the original 9 speed version?

    If you're running outboard bearings, then remove the driveside spacer and put it on the other side. Alternatively, shift the rear hub along the axle and redish the wheel.

  6. #6
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    Have you put the bike upside down and had a look at the chain line when it's in the troublesome gears? I have had a similar thing, and when upside down there was a also a bit of vibration from the chain. The chain needs to lead dead straight through the derailleur / tensioner and onto the cogs.

    Whatever, with the bike on its head you can really look at what's happening.

    Nick

  7. #7
    Just a flesh wound
    Reputation: Prophet Julio's Avatar
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    Find the center

    The new setup is working(?), but the centerline of the cassette and crank is different. If you are getting this noise in the 2 large cogs then you should move the crankset in toward the center. Maybe the angle is too much and the front derailleur is rubbing (barely) when you are in these large cogs.

    You did not mention Big BIg, so you are obviously using proper shift ettiquette but it is probably worse in big big or b b less 1.

    silence is goodhttp://forums.mtbr.com/images/smilies/smile5.gif

  8. #8
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    There's no rubbing of any sort on the front derailleur. There is definitely serious cross chain when in the middle chainring and largest two cogs. Sure, the sound gets worse in the big big combo, but that's only been tested out on the bike stand. I'm only in the big ring when in the center or smaller cogs. I'm running a 113mm spindle on my bottom bracket, and don't dare run a shorter one. The inside of my crank arms don't have much clearance at the chainstay. Dave Turner recommends a 113mm spindle for those who still use traditional cranksets.

    In preparation for Saturday morning's ride, I spent some more time on the problem Friday night. I noticed the chain is ultra close to to the next largest cog when in the upper cogs. However, there is noticeable space between the chain and the next largest cog when down in the lower cogs. I also noticed while on Saturday's ride that when the cable is dialed to perfection in the lower cogs that the shifting was ever so slightly sloppy in the upper cogs. Last night I pulled the derailleur hanger off and layed it flat on the counter top comparing it to a new hanger. I ended up bolting on the new hanger and now there is no difference in chain to next upper cog clearance along the entire cassette. I'll report on the larger cog noise after my next decent sized ride. Probably shouldn't be any later than Tuesday evening.

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