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  1. #1
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    XT M8000 Crankset install - BB Drag?

    Hi folks,

    I'm building up a bike for the first time. Last night, I installed the BB-MT800 and FC-M8000 1x crankset. After putting everything together, I gave the crankset a push and saw that it didn't spin freely. A gentle push gets 1-2 revolutions, and a hard push gets 5-7 revolutions. Is this normal?

    Some things I noticed upon installation:
    • The bottom bracket had lots of green grease on the inner part where the axle goes through.
    • The axle did not go through easily. I had to use a hammer (crankset protected by a cloth) to drive the axle through the bottom bracket.


    Is this user error? Did I over-tighten the preloading component? Will the drag work itself out with some riding?

  2. #2
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    I see that your post is about a month old and you've likely worked this out.

    Having a new build with new components and particularly new bearings with factory original grease can result in some increased drag until the component has some time on it. It's common to have to tap the crank arm into the BB bearings with a rubber or plastic hammer. A good, snug fit is normal.

    The green grease is the factory Shimano grease. I lube the crank arm to assist in the install of going through the BB bearings.

    The preload on the crank arm is a little sensitive to the slightest over-tightening. A little trial and error will usually find that 'sweet spot'.

    As a personal preference, I don't see much water in my environment, so I prefer a lighter grease like Buzzy's Slick Honey on the BB. It offers a lower coefficient of friction. Use of a lighter grease has its trade-offs. Increased service intervals, but i'm ok with that.
    A bad day of cycling is better than a good day at work

    Work Truck - Dassault Falcon 7X

  3. #3
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    Thanks for the info. I've put about 50 miles on the bike so far, and the cranks and BB seem to be working perfectly. I'll probably pull the cranks off at the end of the season and look at the BB, but so far so good.

    I recently rebuilt my SPDs with Phil's Waterproof grease. It seems a bit lighter than the sticky Shimano grease, so I might re-grease the BB with that as well.

  4. #4
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    Phil Wood's Waterproof Grease is hands down, a high quality lubricant. Long lasting and it has stood the test of time and I think no one can say anything bad about it.
    A bad day of cycling is better than a good day at work

    Work Truck - Dassault Falcon 7X

  5. #5
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    Quote Originally Posted by Cleared2land View Post
    Phil Wood's Waterproof Grease is hands down, a high quality lubricant. Long lasting and it has stood the test of time and I think no one can say anything bad about it.
    From the 100 posts here I've seen, it's nothing more than what I use

    Marine bearing grease. $5 for a tub big enough to last forever.

    Sent from my XT1565 using Tapatalk

  6. #6
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    ^^^^ I agree with that statement too. No doubt that you will pay the premium should you elect to use a 'bike branded' grease. What ever makes you feel 'warm and fuzzy'.
    A bad day of cycling is better than a good day at work

    Work Truck - Dassault Falcon 7X

  7. #7
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    I wouldn't trust any bb that let the crank spin freely. That grease is important!

  8. #8
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    Quote Originally Posted by Schulze View Post
    I wouldn't trust any bb that let the crank spin freely. That grease is important!
    A quality grease does not necessarily mean that it has to have a high friction coefficient. Grease is important, but that doesn't mean that it has to create excessive drag.
    A bad day of cycling is better than a good day at work

    Work Truck - Dassault Falcon 7X

  9. #9
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    Quote Originally Posted by Cleared2land View Post
    A quality grease does not necessarily mean that it has to have a high friction coefficient. Grease is important, but that doesn't mean that it has to create excessive drag.
    X10. Marine grease is better yet crank spins more freely than stock Shimano grease.

    Sent from my XT1565 using Tapatalk

  10. #10
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    Cool-blue Rhythm BB installation extra steps

    Many older bikes may never have had a proper BB facing done. Once an arcane step when the sealed can type units prevailed, this old step was and now is again imperative to assure that the outer faces of the frame are parallel, so that the cups and bearings will be parallel upon installation. The threads alone do not do this, and can pull the cups off, which will make the bearings run tighter and wear prematurely. The seals and grease make even good installs seem tight at first, but will have negligible impact after break-in - ignore the silly ceramic bearing videos. I use both antiseize and blue loctite on the cup threads to preclude loosening/creaking later; the cups are very hard to overtorque, but the rest of the crankset torque specs should be followed closely to avoid too much bearing preload, and damaging the alloy threads of the crank arm.
    Shimano uses as good a grease as you will find, and it is a waste to try swapping out for any recommended alternatives. For servicing, Slick Honey is about as good as Shimano, and much more water resistant than Phil or Park greases, and looks clean months later when the next servicing is done.

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