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  1. #1
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    Reputation: eddieshowcase's Avatar
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    BB spacer questions for SS

    hello,

    slowly building up my first SS 29er. I scored a FSA V-drive crankset (outboard bearing setup) off fleabay for supa-cheap.

    I've always just followed the instructions on my geared bikes, typically (for Shimano) have 1 drive side spacer for a 68mm shell if I remember correctly.

    But with FSA, the spacer configuration is different, calling for all 3 spacers on a 68mm shell, one on the left, two on the right. I realize with a SS, the spacer configuration is *less* important and can be used as a way to tinker with chainline... but a few questions:

    1. Can someone remind me what the difference is between a 68 vs 68E BB shell is? There's a different spacer config for each, and isn't clear what 68E is, all I know is my shell measures out to 68mm.

    2. Should I always follow the correct number of spacers? I'm assuming so that the plastic tube seal that goes between the two cups is correctly seated into the two cups? Make sense? Or am I missing the point.

    3. Based on the recommended configuration, with a single front chain-ring (in middle or outer position), seems to put the chainline way out there.

    I only have experience with Shimano cranks, so this is my first FSA crank... first SS setup, so looking for a little guidance from your experiences - folks who have gone through this.

    Thank you!

  2. #2
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    Reputation: boomn's Avatar
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    1) 68E is not a different bb shell, it is a configuration for a standard 68mm bb shell with an e-type front derailleur (like this) or some other device that would mount behind the bb cup and has the same thickness as a standard spacer. That's why the 68E config calls for one less spacer on the drive side

    2) Yes, you must use the specified amount of spacers. The spindle is a certain length so that the non-drive side crankarm can tighten up directly against the bearing to preload it. If the distance between the cups is too small then it might not be able to tighten up against the bearing.

    3) Measure the chainline to check against the manufacturer's spec. Horizontal from the middle of the middle chainring position to the center of the seat tube.

  3. #3
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    Quote Originally Posted by boomn
    1) 68E is not a different bb shell, it is a configuration for a standard 68mm bb shell with an e-type front derailleur (like this) or some other device that would mount behind the bb cup and has the same thickness as a standard spacer. That's why the 68E config calls for one less spacer on the drive side

    2) Yes, you must use the specified amount of spacers. The spindle is a certain length so that the non-drive side crankarm can tighten up directly against the bearing to preload it. If the distance between the cups is too small then it might not be able to tighten up against the bearing.

    3) Measure the chainline to check against the manufacturer's spec. Horizontal from the middle of the middle chainring position to the center of the seat tube.
    Good info, thanks for the reply. That tells me I have the right spacer config.

    For a SS set-up on a triple MTB crank is it typical to put the chain-ring in middle or outer position? Or doesn't matter as long as the chainline is good? (I have a geared 9spd freehub, so I can put the cog anywhere)

    Also, I can't seem to get the preload just right so the cranks spin freely but not without play. Either too tight or too loose. Even though my LBS said they faced and chased the BB, there's still some paint on edge of the BB ... he said the shell measures out to be flush/parallel/coplaner, but I wonder if he did it half-arsed and could that cause preload issues? Or perhaps the fact that the bearings are so new, they just feel sticky and will break in. Thanks again.

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