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  1. #1
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    Chainslap help needed

    My Cannondale RZ140 3Z has a Hammerschmidt front crankset. The chain runs very close to the chainstay and is constantly hitting it while riding. I have some innertube and self sealing tape wrapped around it to help protect it, but its getting to the point where I have to replace/repair it every other ride.

    Is there a chain guide I could install that would help to reduce chainslap?

    I'm not sure if i have a medium or short derailleur. How can i tell the difference?

    Would shortening the chain help?

    Hope this picture helps.


  2. #2
    Tool
    Reputation: Pedalphile's Avatar
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    When it comes to chains, shorter is almost always better.

    I assume your chainguard is wearing out on top? Either way, I've found old mouse pads to be very durable chainguard material, and they're easy to find for free. And no, I'm note referring to sanitary napkins for mice.

    Good luck,
    Pete
    I can barely get my mouth around it.

  3. #3
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    Quote Originally Posted by Pedalphile View Post
    When it comes to chains, shorter is almost always better.
    How short can I go? As i shorten the chain, the derailleur tension will increase, which should reduce slap, but there must be a reasonable limit.

    Quote Originally Posted by Pedalphile View Post
    I assume your chainguard is wearing out on top? Either way, I've found old mouse pads to be very durable chainguard material, and they're easy to find for free. And no, I'm note referring to sanitary napkins for mice.
    Its wearing on the bottom just to the right of the protection applied in the photo. I added a lot more since I saw it was still hitting the chainstay.

    On an early bike (around 20 years ago), I had an aftermarket chain guide mounted halfway down the chainstay that had a derailleur cog attached that the chain ran through, effectively halving the length of floating chain that could flap about. It worked really well, but i can't see anything like than now, that would fit the rectangular chainstay of my RZ.

    I like the mouse mat idea. are you talking the fabric or plastic covered ones?

  4. #4
    Nouveau Retrogrouch SuperModerator
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    Quote Originally Posted by BritOnTour View Post
    How short can I go? As i shorten the chain, the derailleur tension will increase, which should reduce slap, but there must be a reasonable limit.
    Let the air out of the shock and completely compress the suspension.

    Shift to the largest cog. The chain should be JUST long enough to easily move on to and off of the the big cog.
    mtbtires.com
    The trouble with common sense is it is no longer common

  5. #5
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    your chain should be almost tight in the biggest front and rear (you only have 1 front, so biggest rear). and the derailure should be stretched out almost straight. they are made for this.

  6. #6
    Tool
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    Quote Originally Posted by BritOnTour View Post
    I like the mouse mat idea. are you talking the fabric or plastic covered ones?
    Fabric - quieter than plastic and durable enough to last a season. I had a black one on hand, and attached it by wrapping black, waterproof duct tape around it in a few spots (as well as sealing the length of the seam with tape).

    That's a tricky area of the bike to wrap things around, though (I couldn't make the mouse pad work there in ten minutes of trying and gave up). On my RZ, I settled for a piece of loop side Velcro in that location. It doesn't really address the noise, but it's protecting the stay. If you go with the mouse pad, you may have luck with 3M double-sided waterproof adhesive.
    I can barely get my mouth around it.

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