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  1. #1
    Senior Member vsopking's Avatar
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    Chain hits chainstay when going over bumps.

    Well that sums up quite nicely what does happen regularly. The first miles on my ride I have to go accross a lot of bumps - which I tend to go over while standing on the pedals and not pedalling for a while. When doing so, the chain hits the frame and I noticed contact/scratch marks on the horizontal chainstay. Not too bad, however is there a way to overcome this chain slapping without pedalling while crossing bumps? If not I may stick some protective tape on the chainstay, but I prefer to keep the frame as clean as possible.

  2. #2
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    is the chain the correct length? as in not too long.
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  3. #3
    Senior Member vsopking's Avatar
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    Well, I ride the bike since a year; and was new a year ago. Does that make sense? How much slack is normal?

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    Great State of Varmint Panthers007's Avatar
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    Not enough to slap the chainstay when going over bumps. I'd pull a link from the chain and test-ride it again. Slap gone? Good!
    Quote Originally Posted by Cateye View Post
    Only panthers007 is stupid enough to believe that this is a good idea.

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    In beaurocratic limbo urbanknight's Avatar
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    I put protective tape on my chainstays. You can get clear contact paper (for kitchen and bathroom shelves) or thicker stuff from a hobby store that sells radio control.
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  6. #6
    Senior Member BCRider's Avatar
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    Slap is normal if the bumps are big enough. Just because you get some slap it's hard to say from here if your chain is too loose or not.

    Chain length is strictly determined by the safe setup of the chain when in the big to big combination. It's not a combo you should be riding in but for length testing it's fine. Shift into that combo and then wiggle the derrailleur. If it can move around a lot then you can take out a pair of links. If it is only moving a little and feels pretty tight then the chain is the correct length.

    It might also be the combination that you're using. If it's a mountain bike and you're riding on the middle ring and a fairly small rear gear then the chain is going to be more slack than if you're in the big front ring and a bigger rear cog. The ratio to you is the same for riding but the chain will be tighter in the big front case.

    It'll also depend on how fast you're riding over the bumps.

    But in the end it's worth taping the stay. You WILL hit things that cause chain slap regardless. It may be on your route every day or it may only happen now and then. But to protect the paint and the metal it's well worth putting a pad on the stay. Done cleanly you won't even notice it. On my road bikes I've used a double layer of electrical tape applied lengthways. I round the ends so it doesn't tend to peel off. Even with winter rains, mud and snow this typically lasts for at least a couple of years if you clean the frame well before applying it. On my mountain bikes I go for the heavy duty solution and wrap the stay with a full spiral wrap of inner tube rubber from a tube cut lengthways into a 2.5 cm wide strip and then overlapped when wrapping it just like bar tape.
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  7. #7
    Senior Member Homebrew01's Avatar
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    Chainstay protectors used to be common for this very reason. They were usually thin, curved chrome strips with double sided tape that you put along the top of the chainstay.
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    To deaden noise like that you need a chainstay wrap that absorbs sound better. Old innertubes are my favorite for my mountain bikes, good to recycle 'em and they do a good job of absorbing the sound and done well they look just fine. If an innertube bothers your aesthetic sensibility try old handlebar tape (assuming you're on a roadish bike) that matches/complements your bar wrap/color scheme.
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  9. #9
    Senior Member vsopking's Avatar
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    Thank you for all tips and tricks !!

  10. #10
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    Before removing any links, try the little ring and smallest cog test. If the lower pulley is applying some tension on the chain and it's not rubbing the upper chain guide tab, then it is not too long.

  11. #11
    Senior Member vsopking's Avatar
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    Tonight, I'll again will bump over some rough roads - on my Specialized comp road bike - I will check out slack when in other gear then usual. Bigger front/bigger cassette wheel; gosh I don't know what number of teeth... I usually try to maintain a straight chain and use the middle front ring and the second/third tiniest back "wheel". I can use the biggest front wheel; but usually this brings the leg motion more down than I want. I like to ride with a cadense of 80+. Well anyway, appreciate any reaction. It's getting colder again over here in Holland; so I have to keep a high cadense to stay warm!

  12. #12
    Senior Member BCRider's Avatar
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    Oh, there's something else you may be able to find. Some years back I got a few sheets of a fairly tough adhesive backed mylar product called Fascal. I've used it on various things including spots on my bikes where cables rub the head tube, frame tubing where a snap on fender clips over the tube and on the snazzy looking road bikes as chain guards for the stay. When on the bike you can't see it at all from more than a couple of feet away and then only when the light hits it a certain way. I don't know why I didn't remember it before. I got the Fascal sheets from a graphic arts supply store. You may find it under another name. It's roughly 2mil mylar with an adhesive backing and comes mounted to a white backing paper that peels off. It won't be cheap when you find it since it IS an art product after all but one sheet will last for a lot of years and a lot of bicycles.
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  13. #13
    Senior Member vsopking's Avatar
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    Thanks to you all - The problem is in fact solved, when changing to the big front ring, the chanin is further away from the chainstay. I did not remove a link - this'll do fine thank you all.
    I may find some protective foil though, just in case.

  14. #14
    la vache fantôme phantomcow2's Avatar
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    Wait, are you saying the problem is solved by simply avoiding the smaller chain ring? If I'm interpreting this correctly, which I may not be, then this is not a solution.
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    Great State of Varmint Panthers007's Avatar
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    The reason chainstay-protectors seem to be a thing of the past is they are no longer silver. They tend to be clear and blend in.
    Quote Originally Posted by Cateye View Post
    Only panthers007 is stupid enough to believe that this is a good idea.

  16. #16
    Senior Member Chombi's Avatar
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    If youdo have the correct chain legnth and you still have the loose/chainslapping problem, you might also check to see if you might have a RD tension spring that is broken, or in some derailleurs, not adjusted properly to provide enought tension for the chainwrap expected on your drivetrain gear ratios.

    Chombi

  17. #17
    Senior Member BCRider's Avatar
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    Quote Originally Posted by vsopking View Post
    Thanks to you all - The problem is in fact solved, when changing to the big front ring, the chanin is further away from the chainstay. I did not remove a link - this'll do fine thank you all.
    I may find some protective foil though, just in case.
    As long as you're not trying to run the drive with a strong cross chaining combination then you just cured this for yourself.

    For my part when running the big ring I like to use a rear cog that is no more than 1/2 way up the cone of the gear cluster. If you're running farther up than the middle cog then you may want to consider getting a smaller big ring for your cranks that will be more in tune with your riding. And if you do get a smaller front ring then you'll likely need to shorten the chain.


    Chombi has a good point as well.

    Phantomcow, it is the right solution if he's riding in the middle or small ring and having to sit the chain on one of the smallest rear cogs. That implies that he's cross chaining strongly to the outside and that the larger front ring would result in using a better rear cog combination. Normally he/we could run either combo but if he's getting some stay slap due to riding in rough conditions then running a combo that is still valid from a chainline standpoint and that results in more wrap will also result in more tension from the derrailleur springs and less chance of stay slap. On top of this by spreading the contact area to more ring teeth some chain and gearing wear is reduced. Win-win-win to my thinking.
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  18. #18
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    Slap is normal, especially when coasting with smaller cogs. Coming off a 13t or 14t cog the chain is only about an inch or so above the center-line of the chainstays so with a fat chainstay it might only be passing as close to 1/2" above the chainstay near the back.

    When you're coasting the upper chain is slack, tensioned only by the RD pulley cage, which really doesn't pull it that tight, so with a decent vertical jolt the bike bounces up into the chain. Long cage RD's also tend to tension the chain slightly less than short cage RDs.

    Shortening the chain won't make any meaningful difference, so don't waste your time. Sometimes a tight freehub mechanism worsens the problem, so check that it's truly free and doesn't push chain into the upper loop.

    Years ago, many RD's had multiple positions for the chain tension spring, so raising tension was an option, but most don't allow much, if any, adjustment anymore.

    The solution is to use a chainstay protector. You can use a stick-on one, or wind an old inner tube around the stay like handlebar tape.
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  19. #19
    BeaverTerror Yan's Avatar
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    Velo Orange sells a classy leather protector in several colours.
    Yan

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  20. #20
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    Quote Originally Posted by phantomcow2 View Post
    Wait, are you saying the problem is solved by simply avoiding the smaller chain ring? If I'm interpreting this correctly, which I may not be, then this is not a solution.
    You are interpreting it, incorrectly
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  21. #21
    Senior Member vsopking's Avatar
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    Did not expected that many reactions - The chain slap when in the big ring and a small ring without overly cross-chaining, does work for me. The effort to push the pedals is approx the same when using the middle ring. Actually, when on smooth roads, I used to ride the front middle ring and the second smallest ring on the cassette. Changing gears usually was done only between middle and biggest ring on front. Now I will need only to change rings on the cassette. one up/one down that is.

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