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  1. #1
    mtbr member
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    Shimano Hollowtech II BB Question

    Does anyone know if I can use HT II road BB cups on a 73mm shell? Obviously the plastic seal that goes in the middle won't reach far enough, but I could use the one from my old BB (or just not worry about it). I've got an XT M760 crank. Thanks.

  2. #2
    Nightriding rules SuperModerator
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    IIRC, the cups themselves fit... somebody has used durace ones, i think..

  3. #3
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    I went to work and did a little experimenting. Here's what I figured out: It works, more or less, so long as you aren't running an e type front derailleur or changuide with a 73mm BB shell. Ultegra cups are 1.25mm wider than XTs. This means that if you use a spacer somewhere in your setup with XT cups, you can ditch it and use Ultegra ones. In doing so you shift your chainline 1.25mm to one side or the other, depending on which side you remove the spacer from. This is more or less irrelevant, and in my case was even desireable, so far as a minute change for the better can be considered a good thing.


    I also had fun disecting my dead XT cup. After a little prying I suceeded in disassembling it down to individual ball bearings. My races, both inner and outer, had nice, uniform, deep pits.

  4. #4
    it's....
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    was there any grease left in the old BB?
    Do you think if it was greased, would've lasted longer?

  5. #5
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    Quote Originally Posted by Strafer
    was there any grease left in the old BB?
    Do you think if it was greased, would've lasted longer?
    Yes, it was well greased.

  6. #6
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    Quote Originally Posted by mountainforce
    This is good to know!

    I just bought a FSA Ceramic BB - its a 68mm road english version, but as you said the only difference is the centre sleeve is shorter so i'll swap it out.

    If the cups on the FSA are thicker i will ditch the single spacer i have on the driveside. Or just file it thinner :-)
    Each cup was 1.25mm wider. The spacers are 2.5mm wide. Ditching the spacer works out very cleanly.

  7. #7
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    [QUOTE=

    I also had fun disecting my dead XT cup. After a little prying I suceeded in disassembling it down to individual ball bearings. My races, both inner and outer, had nice, uniform, deep pits.[/QUOTE]


    The enduro seals XT cups are great last a very long time and run too fast.

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