Chain tensioner

Discussion in 'Motorized Bicycle General Discussion' started by jototojo, May 16, 2011.

  1. jototojo

    jototojo New Member

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    Hi people,
    From argentina again, hahaha.
    The other day i was ridding on my recently build 2 stroke bike when i hear a "clack" sound, and i see that the plastic part of the tensioner that turns around and guides the chain like moves from right and left, only the plastic part, the metal part is welded to the bicycle.
    So this makes the chain go to the centre part of the wheel and finally it goes off the sprocket.
    Guyyyss, WHAT CAN I DO!!???
    HELP pleassse.
    Thanks again.
     
  2. rohmell

    rohmell Active Member

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    So, you say the plastic part is loose?
    Maybe epoxy it back to its proper place?
     
  3. jototojo

    jototojo New Member

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    But it turns with the chain, it wont break?????
    Thanks.
     
  4. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    Put a washer beside it to hold it without being too tight.
     
  5. jototojo

    jototojo New Member

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    And then i put epoxy???
     
  6. rohmell

    rohmell Active Member

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    It looks like this?
    tensioner-1 (1).jpg
    Then put epoxy between the plastic part and the bearing so that they both turn as one unit.
     
  7. jototojo

    jototojo New Member

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    Ohhhhh, now i get it, ok, thank you so much.
    I really apreciate it.
    Thank you.
     
  8. jototojo

    jototojo New Member

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    Hello people again, i still cant fix this problem, i think im gonna cut the part i welded so i can move the chain tensioner far from the wheel, what do you think???
    Thanks.
     
  9. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    Can't you just bend it??
    The tensioner needs to 'feed' the chain straight on to the sprocket, or the chain will derail! (so don't move it away from the wheel too much.) ;)
     
  10. jototojo

    jototojo New Member

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    With what??
    Do you think i can heat it with something and try to bend it???
    I dont know with what can i do that.
     
  11. Allen_Wrench

    Allen_Wrench Resident Mad Scientist

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    I want to see if I understand what is happening here: is your chain-tensioner and guide wheel "in-line" with the chainstay that it is mounted to? - ie. the same chainstay that runs from the wheel hub to the bottom bracket at the seat post? Or did you twist the chain-tensioner's own bracket a little so that the guide wheel runs in line with the drive chain and the rear wheel itself?

    The drive chain does not run in the same exact line as the chainstay your tensioner is mounted to.
     
  12. Allen_Wrench

    Allen_Wrench Resident Mad Scientist

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    I just used a bench vise, channel-locks, a measure of caution, and a pint of sweat.

    I approached the proper angle by trial-and-(very little) error.
     
  13. adam valentine

    adam valentine New Member

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    i managed to do without a tensioner on my 7 speed with good bike shop chain and a half link so for 300 miles and no regrets
     
  14. Allen_Wrench

    Allen_Wrench Resident Mad Scientist

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    And if you can pull that off, that is the best plan by far I think. Those little "chain tensioner/guide wheels" cause almost more trouble than they're worth sometimes. Alas, my chain would slap the chainstay without one, no matter how I futzed around with the engine mount location. So I'm stuck with using one. And I envy you, Adam.
     
  15. jats

    jats New Member

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    if your chain stay is tapered shim the narrow end with a chunk of rubber so the roller is inline with the chain get a good chain and check your alinement's
     
  16. 2door

    2door Moderator
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    Instead of shims it's better to secure the bracket solidly to the chain stay and bend, twist actually, the bracket to get the wheel to align with the chain path. The problem with relying on a rubber shim is that eventually over time it will compress, loosen and there goes your alignment.

    Tom
     
  17. jats

    jats New Member

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    yeah when i pulled it a part today the shims had become distorted but with out them I have to place the tensioner mid chainstay. after tweeking it around it runs great but now it vibrates at speed. left the chain guard off and the chain is vibrating a lot on the top run the alignment is good and its a new chain (410 garage door operator chain) am trying to come up with a damper thought about using a rear derailer but have not figured out how to mount it. looked at some other posts and the farm tensioners they are adapting
     
  18. 2door

    2door Moderator
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    If the alignment, sprocket concentricity and tension are right, there should be no reason for the chain to "vibrate" unless you have rollers that aren't rolling or a twist/kink in the chain. Look at your rear sprocket closely. Lift the rear wheel and spin it and make sure the sprocket is absolutely centered on the hub with no wobbles or up down movement.
    If that sprocket is right on the money and the chain alignment and tension is correct the chain should ride smoothly over the sprockets both front and rear at any speed. It might waver slightly up and down across the slack portion but it shouldn't "vibrate".
    Take the master link out, remove the chain and pull it over your finger from one end to the other to make sure it has no binds anywhere in its length. Even one stiff link can cause you to have a rough running chain. Oh, and make sure its lubed correctly.
    Tom
     
  19. jats

    jats New Member

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    the chain is new and is garage door operator chain i centered the rear sprocket by checking the teeth during rotation of the rim its less then a 1/16 out of flat. the chain is a good quality and looks to be the same size as the trashed China chain and takes a 410 link. Also i use a chain tool so I do not use a master link but have been splicing chain since the early 80's wonder if that could be the reason? is BMX chain a better quality they look and feel the same but that dose not mean much
     

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