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  1. #1
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    Shifting and derailleur problems

    Okay, I have a Trek 4500 SL and I have been having a lot of problems with my front AND rear derailleurs. My front derailleur has been having problems with down shifting from second to third. I tried futzing with my L Screw, and it shifts a little better now, but still sticks and makes some noise and then goes down. The derailleur isn't amazingly nice, so I don't expect it to shift perfectly smooth; but this is getting to be a pain in the ass when I'm riding and down shift but am still riding in second. Also when in third gear up front, when I peddle hard at all, it makes a kind of cracking/cranking noise, and I don't know where to start.

    My rear derailleur is more of a problem though. The rear derailleur shifts fine both up and down, but when in any gear up front 1-3; the rear derailleur has problems in 1-4. Any hard peddling again will make the chain skip, like it has lost all tension. It doesn't always lose tension, but when peddling it will always skip a little, and it's noticeable if you watch the tensioner; it kind of pops every three seconds when peddling. I have just gotten this bike a little over two months ago, and I don't really know what to try and tweak on it, all I know is that the problem is progressively getting worse, because when I got the bike the read derailleur had none of these problems, although the weird noise on the front derailleur has always been present.

    Is it possibly just the chain that needs to be replaced, or would I be well off to just replace the whole derailleur system.

  2. #2
    Senior Member Steev's Avatar
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    If it does this skip with such regularity, then you probably have a stiff link in the chain. Watch carefully as the chain runs through the derailleur and you should be able to see it.
    The other stuff with the front sounds like sticky cables. I'm guessing you bought the bike used and it wasn't too well cared for by the previous owner. Replacing the cables and housing would be a good move. Probably brake cables and pads as well. I would suggest replacing the chain as well but if there's a lot of stretch you may end up replacing most of the drive-train if you do.

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    I bought the bike new from Trek like two months ago. Since then I have had to take it back for warranty because the peddle arm had fallen off mid ride. I thought that it was a stiff link too, but it happens too frequently to be just one link. It happens every like 2 seconds, and my chain in not circulating that fast.

  4. #4
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    Sounds like cable tension is not adjusted properly. On the back of rear der and on the frame there are adjusters. I put the bike upside down and adjust it. Then hold it up and fine tune it: here is nice article http://sheldonbrown.com/derailer-adjustment.html


    After a lot of miles and not a lot of good cleaning I noticed that my shifting became lousy. Turns out to be friction in cables and underneath the frame where it routes over plastic router. Solution was to clean that router cleaner and lube it with grease. I also replaced all cables and housings with dura ace SP41 set (amazingly $12). This had dramatically improved my shifting.


    Also getting rid of stock KMC chain in favor of SRAM helped a lot.


    As you can tell I'm no expert. I had a new bike that went south after I start using it. That's how I got it back into shape though. Hope it helps.



    Another thing: according to my front der instructions, to shift front cog I must put the rear der in largest (lowest) gear first. Rear those adjustment instructions and adjust front der from the scartch after you done with the rear der. Working your front der when it's crap could cause front shifter to break teeth if you apply too much pressure. I had to take the front der off and set my own height and side ways angle for optimum performance. It seems that manufacturer's and bike shops (most) stink at doing things right. Those instructions above really do wonders when followed.

  5. #5
    Elitist Troglodyte DMF's Avatar
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    Quote Originally Posted by Diggidy View Post
    It happens every like 2 seconds, and my chain in not circulating that fast.
    bzzzt! That is about how fast the chain goes around. Typical cadence is roughly 60 rpm, and the chain is roughly twice the chain wheel circumference.

    Think stiff link.
    Last edited by DMF; 07-29-07 at 01:16 PM.
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  6. #6
    Elitist Troglodyte DMF's Avatar
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    Quote Originally Posted by notzofast View Post
    Another thing: according to my front der instructions, to shift front cog I must put the rear der in largest (lowest) gear first.
    Who makes your FD, Mattel? That's the silliest thing I ever heard of.
    Stupidity got us into this mess - why can't it get us out?

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    Well. Shimano of course. Look for PDF for 4400 front der. (or 4400 shifters).. Don't question me in this area. I can bet $20 that I read this silliest thing in the docs!!

  8. #8
    Elitist Troglodyte DMF's Avatar
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    Quote Originally Posted by notzofast View Post
    Well. Shimano of course. Look for PDF for 4400 front der. (or 4400 shifters).. Don't question me in this area. I can bet $20 that I read this silliest thing in the docs!!
    Check for yourself.
    FD
    Shifter

    I take Paypal.
    Last edited by DMF; 07-29-07 at 02:56 PM.
    Stupidity got us into this mess - why can't it get us out?

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  9. #9
    Senior Member mike's Avatar
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    Sounds like it could be a cable or a shifter problem - resulting in sudden change in cable tension.

    First, check the cable. I will attach a photo of a cable problem I found inside cable housing. After trying to get a rear derailure to work properly.

    Also, check the shifters. What kind of shifters do you have? Any chance you can send a pic? If your shifters have some kind if friction device, it might need to be tightened.
    Attached Images Attached Images
    Mike

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    Thanks for the help guys, but I finally got fed up with checking for stiff links or bent plates, so I took it to Trek because it still has it's warranty on it. Took the guy 20 minutes of futzing around and then test riding it to figure out what was wrong, the whole cassette is bent. I don't know how it happened, I haven't had any big crashes or anything on it that would bend it, and it was pretty much brand new so I don't see how just regular peddling stress would bend it this fast. Anyways, Trek is replacing it as we speak.

  11. #11
    Senior Member Bill Kapaun's Avatar
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    If you don't need the 32T cog, maybe you can get them to swap in an 11-28? Save an ounce+ too!

  12. #12
    Senior Member mike's Avatar
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    Quote Originally Posted by Diggidy View Post
    Thanks for the help guys, but I finally got fed up with checking for stiff links or bent plates, so I took it to Trek because it still has it's warranty on it. Took the guy 20 minutes of futzing around and then test riding it to figure out what was wrong, the whole cassette is bent. I don't know how it happened, I haven't had any big crashes or anything on it that would bend it, and it was pretty much brand new so I don't see how just regular peddling stress would bend it this fast. Anyways, Trek is replacing it as we speak.
    Holy smokes; a bent cassette. How did you do that?! Did you bend the axle too? This is a new one for me.
    Mike

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    I really don't know, I was kind of surprised when the mechanic told me. He told me that it can happen from heavy peddling stress when shifting, which I thought seemed strange, because I figured it would take a LOT to bend a cassette. I haven't had any bad crashed on the bike, nothing. The biggest drops I have taken it off of was like 2 feet, so I'm just so baffled as to how I bent a cassette.

  14. #14
    Elitist Troglodyte DMF's Avatar
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    Sure it wasn't the dérailleur hanger that got bent? I can't imagine what there is in a cassette to bend! The cogs are individual pieces (one of which might bend) and the freehub is a near-solid block of metal, as is the hub into which it mounts. Perhaps the retaining bolt? But that's pretty beefy and lives under tension, not torsion. Color me skeptical.
    Stupidity got us into this mess - why can't it get us out?

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