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  1. #1
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    XTR BB-M952 confusion!

    My '97 (first build) Ibis Szazbo bottom bracket has finally bit the dust (M950), may it rest in peace. I have some original FC-950 cranks which are in pristine condition. Looking for a replacement BB has been kind of confusing. I see that their are still some BB-M952 units available and I need a 112.5mm / 68. When I went to the Cambria site they have some comment under the part on their web page
    From Cambria web page:
    Fits FC-952 only as snap ring is missing to fit FC-950/951 series cranks in 112.5 length. 116mm fits all three models.

    So, since I have FC-950's cranks are they saying this about just the one they have in stock or will I have to run a 116mm. and what snap ring are the talking about, the snap ring I notice is on the back of the spline nut assy on the right crank/chain ring assy. Any assistance greatly appreciated I'm having to ride the road bike since the Szazbo is down, really need to get going again. Thanks, Mike

  2. #2
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    I have seen this disclaimer before and I don't know the deal either. I can tell you that I have run several 952's on my 950 cranks (and I say several because the 952 are greatly inferior to the 950 needle bearing BB's) and everything has been fine.

    Call Cambria and ask. But my first thought is that everything should be ok.

  3. #3
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    Pisgah thanks for the suggestion but Cambria was no help. But, I picked up a BB-M952 112.5 sealed Bottom Bracket cartridge. Used an Old BBT-2 (had to open up the hole to accommodate the larger spindle) tool to do the install, everything looked great. Reassembled the crank assy and went for a test ride. Heard a litlle creaking, removed cranks to check torque on BB (used plenty of Anti-sieze) everthing looked good. Then I looked at the inside splines on the crank arms and saw small shaving from the New BB spindle. Seems as the New spindle instead of having 90 degree cuts on the splines has a radius and caused some of the material in the crank arm to be shaved maybe .002-.004 slivers. All the compatibility charts indicate that the M952 BB is compatible with the XTR FC-M950 cranks. hope I didn't just trash perfectly good cranks Ouch! Any recommendations.

  4. #4
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    They are compatable and the splines are the same (I feel certain). You may have tightened the crank onto the splines causing the metal to smash together. I have seen this happen before. If you are a little off when tightening, it's metal on metal. Once this happens you can get perma-play in the cranks. Hopefully it's not that bad and you can keep riding it. You can try some lock tight in the crank to make up for some of the play if it is that bad.

    I still use 950 and 952 cranks to this day and have run both bottom brackets many times.

  5. #5
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    Here are a few images, Sorry they are so Large but its hard to see what I'm talking about.
    The BB-M952 has a larger radius at the base of the spline, which inturn milled a sliver of the crank arms spline. Good suggestion on the mismatch of the splines during initial install but I know I had them in the groove.
    Attached Images Attached Images

  6. #6
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    But you can still use the BB952, right?

  7. #7
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    yes the BB is ok. just hope the cranks can be salvaged. still seems odd how the new BB cut the edges off the crank splines. definetly a mismatch.

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