how much chain slack?- Mtbr.com
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  1. #1
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    how much chain slack?

    Sorry for the newb Q. I have my maintenance manual on order from Amazon.

    But what's the proper chain slack?

    I have a Redline Flight 29. 32/20 gearing.

    It's obviously loose (I dropped the chain on last night's ride) but I don't want to overtighten it. I was going to eyeball it last night, but didn't have the time.

    (on a group ride last night. New trails. 13 riders. I was the only one on a rigid SS. )

  2. #2
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    Tension the chain until it just starts to bind at a tight spot while turning the cranks over slowly... then ease off the tension just enough so it no longer binds at that spot. If this makes the chain too loose at some other crank position, then you need to re-center your chainring. You will generally have less than .25" total movement (up and down) at any point in the chain travel.

    Any tighter, and you will damage bearings... any looser and chain drop becomes more likely.

  3. #3
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    Agh! sunset1123 beat me to it!

  4. #4
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    Quote Originally Posted by umarth
    Agh! sunset1123 beat me to it!
    just say "+1" and then you can still look helpful

    1/4" of slack is what I shoot for too

  5. #5
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    +1...
    "He was a wise man who invented beer."
    -Plato

  6. #6
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    Quote Originally Posted by sunset1123
    Any tighter, and you will damage bearings... any looser and chain drop becomes more likely.
    I gotta ask, as this has been bugging me for a while. Tight but not enough to bind chain tension should not cause the bearing damane, no? You pedal the snot out of the cranks, that having tight chain isn't anywhere near the amount of torque you put down on the bearings by pedaling, is it? Should avoid putting any more stress on the bearings, for sure, but just tight but not binding chain tension shouldn't be a concern, should it not?

    BTW, I always run chain with a slight slack.

  7. #7
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    try backpedal test

    i adjust mine till taught then back pedal...if there's any drag at all i release slowly until it just begins to back-pedal freely (or the clunking of the chain stops).....i don't care how much chain slack there is at this point but there shouldn't be much

  8. #8
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    Quote Originally Posted by hatake
    I gotta ask, as this has been bugging me for a while. Tight but not enough to bind chain tension should not cause the bearing damane, no? You pedal the snot out of the cranks, that having tight chain isn't anywhere near the amount of torque you put down on the bearings by pedaling, is it? Should avoid putting any more stress on the bearings, for sure, but just tight but not binding chain tension shouldn't be a concern, should it not?

    BTW, I always run chain with a slight slack.
    Here's the situation: when you are pedaling, the top of the chain becomes loaded, and transfers a tangential force to the hub. Fortunately, the hub rotates, so the force can be translated into forward movement.

    With a chain that is too tight, or nearly binding, both the top and bottom of the chain become loaded, and transfer a force to the hub which is now equally perpendicular to the axle. The hub cannot move forward b/c it is secured to the frame. Thus, the force is transferred to the drive side hub bearing and translated into friction, heat and wear.

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