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I ride a BMC FS-02 mountain bike which came with a Shimano XT group, including a FC-M785 XT Crankset (2X10). The bottom bracket is apparently included in that and mine is showing some signs of wear.

I'm new to the press-fit bottom bracket and am trying to figure out what a good replacement is and what exact dimensions, if any, I need to be aware of.

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TL;DNR - I recently had exactly the same problem with my 3x10 XT MTB and handed the job to the LBS.

You need to be aware the great thing about standards is when you can't find one that suits you make a a new one. The Cycle industry took this to new extremes since the early 2000's with regards to Bottom Brackets. The BB matches the crank set to the frame, so you half of the equation knowing the crank set. The manufacturer and all my normal goto references for bike specs are silent on the BB standard of the frame.

If the BB is press fit, its probably BB30. Have a look on the lower seat tube - some manufacturers helpfully print use information on BB.

If press fit, this is one job that might be better left to your LBS - you probably won't have the correct tools to do it yourself, correct tools are expensive and DIY cobbled together tools can easily stuff a frame. With the correct tools the LBS has, it is a 30 minute job, and that 30 minutes comes with years of experience.

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The BMC FS-02 has a BB92 Shimano Press-Fit.

The answer was on the BMC website on the FS 02 page under technical details > concept

BMC FS 02

For removal and installation refer to mattnz's post, ie. visit your LBS.

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  • Good spotting, I presumed the specification for the BB would be in the Specifications section... silly me....
    – mattnz
    Aug 3 '16 at 9:45
  • Nice...thank you! I had perused around there but missed that page. That's immensely helpful. I dropped by my LBS today and have a some new bearings on order. They assured me they're pretty easy to swap out and don't require the special tools to remove/install the press fit BBs.
    – brianz
    Aug 3 '16 at 23:05
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This is a specific bottom bracket for the crankset. I am unsure why you may think that this is a PF system, as BMC does not list it as such. Shimano lists the BB accompanying the crankset as a Hollowtech-2 system. Many(but not all) PF BB are significantly larger in diameter (30mm), while the hollowtech2 system is 24 mm for the crankset spindle. The hollowtech2 system is an external cup system and a very good one at that.

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  • I know it's a press fit since there are no externally exposed cups. The BB/bearings are flush against the frame.
    – brianz
    Aug 3 '16 at 2:12
  • Been wrong before. There is an internal 24mm diamter pressfit BB made by Shimano. It fits the hollow tech series. BMC did not mention this. It kind of side steps the whole bigger spindle is better argument though...For you, this means that it has to go to the shop, unless you happen to have the special tools for removal and installation. Good luck.
    – user26705
    Aug 3 '16 at 20:14

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