Bottom bracket upgrade question: PRESS-FIT system size 86.5 X 41
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  1. #1
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    Bottom bracket upgrade question: PRESS-FIT system size 86.5 X 41

    I have a Basso carbon frame that needs a crankset upgrade. The original crankset is a Miche "EVO Max" with 24mm bearings on both sides. Basso said that the frame is compatible with BB 72 SHIMANO or any other brand with PRESS-FIT system size 86.5 X 41 - axle diameter 24mm.

    Would I need to extract the original cups out of the frame and install a new BB? Since Shimano also uses 24mm bearings on both sides, would any Hollowtech II crankset work, or would it need to be specific for Pressfit?

    Thanks in advance!

  2. #2
    'brifter' is f'ing stupid
    Reputation: cxwrench's Avatar
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    Any 24mm Shimano crank will work.
    #promechaniclife

  3. #3
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    Wow - Thanks cxwrench ! I appreciate the advice!

  4. #4
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    I tried to install a Shimano Hollowtech II double crank. If I tighten until there is no lateral play, than the crank arms rub the edge of the press-fit BB shell. Would a spacer of some kind between the bearings and the crank arms work? Maybe something like the spacer that comes with Shimano Hollowtech II triple crank, though that might be too thick. Any ideas?

  5. #5
    'brifter' is f'ing stupid
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    You must be missing some spacers or bearing covers...something like that. ALL Shimano cranks are the same. Their axle length is based on a normal threaded bb shell (either 68 or 70mm width) and bearing cups (either 11mm or 10mm) to bring the total to 90mm. If the total of frame/bb doesn't come out to 90mm then some kind of spacers are needed. They should come w/ the bottom bracket, NOT the crank or frame.
    #promechaniclife

  6. #6
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    Would a thinner spacer or dust seal like this help:


    Wheels Manufacturing 24mm BB Spacer Pack

    https://www.amazon.com/Wheels-Manufa...2Aentries%2A=0


  7. #7
    'brifter' is f'ing stupid
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    Possibly.
    #promechaniclife

  8. #8
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    I figured it out! I needed a wave washer on the non drive side between the BB cup and the bearing. That pushed the bearing out so that it was the correct width. No spacer was needed.

  9. #9
    'brifter' is f'ing stupid
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    That doesn't sound like the correct fix to me. You NEVER put anything between the bearing and the cup. If you had the problem you described a spacer of some sort was the correct answer. Shimano crank/bb NEVER use a wave washer.
    #promechaniclife

  10. #10
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    Thanks. The non drive side Evo Max bearing cup is a bit deeper than the drive side. The wave washer pushed the bearing out to the same dimension as the drive side. I guess that I could add spaces on the outside of the bearing instead.

  11. #11
    'brifter' is f'ing stupid
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    Quote Originally Posted by Erik_A View Post
    Thanks. The non drive side Evo Max bearing cup is a bit deeper than the drive side. The wave washer pushed the bearing out to the same dimension as the drive side. I guess that I could add spaces on the outside of the bearing instead.
    That's the right way to do it. The bearing will move in the cup and make your life miserable w/ a wave washer behind it.
    #promechaniclife

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