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  1. #1
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    Shimano Derailleur Problems

    Okay, I've been searching around this forum and the mechanics forum for three days now and can't find any answers. I bought an '06 Rockhopper disc comp last week, rode it around checking it out on the flat a little before I took it out in the woods and everything was glass smooth, shifting was flawless, brakes are great. Took it into the woods down a pretty rough downhill hill run, road it around for three or four hours and took it out on a flat paved rail trail a couple days later where I noticed that shifting into AND out of the next to the last three smallest cogs on the back I get a loud clunking noise. I took it back to the shop where three different mechanics looked at it and can't see what's causing the problem, they changed the cable, tried to adjust everything, replaced the rear cassette (which actually showed wear on the gears in question after only about eight hours of riding).
    Now I am a new rider and my technique is certainly lacking but I'm not cross chaining, I can't see what I'm really doing wrong here and neither could the shop mechanics. They sent me out with instructions to ride it and bring it back in a couple weeks.
    They did not see any indication of the derailleur being hit or anything, no sign of damage from the outside. Could something simply have vibrated loose? This is pretty annoying in a brand new bike, I did get a couple hundred off for taking last year's model but still, seven hundred bucks for a bike that doesn't shift well? I ain't a happy camper right now, when I bring it back does anyone here have any advice on what else they should check? They looked it over for about an hour and a half and were stumped.

  2. #2
    Big Ring Circus crash13's Avatar
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    Is the derailleur hanger bent? I'd check that out. Also, make sure the derailleur cage is not bent and the pulleys are inline.
    Other than that, I's ask them to replace the derailleur and hanger and see if that solves the problem. If not, find a new mechanic or bike shop.

  3. #3
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    I really don't know if anything is bent, it's possible a rock may have spun up and wacked it but there are no marks on it. The mechanics gave it a pretty good going over and didn't see anything like that. The shop in question is the biggest in the area, Gearworks in Leominster Mass. they have a good rep.
    Thanks for the reply.
    If these things are this fragile I'm in trouble, I didn't consider what I did to be that hard of riding. Reading many reviews on that derailleur I've seen a lot of guys that love them and just as many that hate them. Perhaps when I take it back I should get something stronger?

  4. #4
    Big Ring Circus crash13's Avatar
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    What derailleur is currently on your bike?
    An XT rear derailleur would be a great choice. I have had 1 for about 7 years and it is stood up to all kinds of abuse. It still shifts great!

  5. #5
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    Sorry, I should have said that, it's the Shimano LX that came stock on the bike. I looked through the mountain of reviews for it online and most people seem satisfied with it, 3 quarters of the reviews are positive and about a quarter say they absolutely hate it. If the cassette is messed up again when I take it back I'll probably just tell them to put an xt on it.
    I wish I knew more about this stuff.
    I was just checking out the wheels and they seem quite a bit out of true as well, I guess I'll have to go easier on the bike until I lose some more weight. The owner of the shop pretty much picked this bike out for me according to my size, I would have figured it could take it. I do still have thirty or fourty pounds to drop but even with no fat I'm still going to be pushing 260 to 270 pounds.

  6. #6
    Big Ring Circus crash13's Avatar
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    Welcome to the game! The fun is just beginning!
    Most modern Mountain bikes are able to put up with a lot of abuse. Rider weight definatley plays into that equation, especially with wheels. An inexpensive (cheap parts, low quality parts) or lightweight set of wheels may not be able to take as much abuse from a heavier rider as would a purpose built set of heavyweight wheels.
    Your LX derailleur should hold up fairly well.
    Quick question: Does the bike shift correctly when on the workstand? Drivetrain load can alter shifting performance.

  7. #7
    Luggite bsyptak's Avatar
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    Try to shift before you start uphill, or at least ease off the pedaling while shifting. Shifting under load wears chains, cassettes and chainrings out. You can just hear it grinding the teeth down. Also, new wheels coming out of true is quite normal. The shop probably told you to ride it 50-100 miles and then bring it back so they can retrue the rims and adjust the cables which also stretch after a bit.

    The XT cassette is no better than the Deore cassette. It's just quite a bit lighter.

  8. #8
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    Yes, the bike shifts well on the workstand, the problem manifests under load. And yeah, at 310 pounds that's a lot of load.

    I know my shifting technique needs some work, as do all my other skills.
    I won't be doing anymore downhill suicide runs untill i know a little more about what I'm doing, I was impressed with the way the bike handled it but it probably was a little more abuse than I should have dished out to it before a proper break in period. I do think something happened to the derailleur though, the mechanics all agreed after trying it in the parking lot themselves that the roughness in those gears was excessive, though they were at a loss as to the reason why.
    For my next trip I plan on a 22 mile trip down the local paved rail trail and really concentrate on getting used to the shifters and minimizing stress on them before I go back out on the local trails.
    Thanks for the input guys.

  9. #9
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    Quote Originally Posted by bsyptak

    The XT cassette is no better than the Deore cassette. It's just quite a bit lighter.

    Sorry for the misunderstanding, I did not mean to replace the cassette with XT, I meant to replace the LX Derailleur with the XT, but only if the damage is not covered by any warranty, a diagnosis still needs to be performed though.

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