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I'm looking for a tool, if it exists, that would allow me to tighten my bottom bracket (SRAM GXP, 16-notch 44mm) without removing the cranks. I have seen a few tools that look like they might work, which are similar to the BBT-9 but with an opening; they are open (C-shaped) instead of closed (O-shaped).

For example:

  • Shimano TL-FC32 and a couple other, cheaper, seemingly identical clones. For this style, what is the minimum separation of the opening? (This is the primary constraint. It seems like an obvious application of this tool but I see no claims or specs.)
  • Park Tool HCW-18 almost pin-spanner style. For this style, are there any compatible?

Applications include simple laziness, testing or temporary tightening the BB before/without removing the cranks, for similar disc brake lock-rings, etc. My primary application in this case is merely grasping the BB cups to adjust an eccentric bottom bracket in lieu of a pin-spanner, and in the process trying to purchase a more flexible multi-tool.

As a counterpoint, is there a good reason not to do this (e.g., potential damage to spindle, etc.)?

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    Does your BB come loose a lot and need tightening? Sounds like you're working on a symptom and not the root problem ? – Criggie Jun 27 '17 at 5:25
  • @Criggie No, frequent BB re-tightening is not really my issue (though you make an excellent point in general). My main problem is EBB adjustment (and emergency/travel tool minimization). I've edited the question to clarify my main goal. – hoc_age Jun 27 '17 at 5:47
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    This is only realistic for bottom brackets like Shimano Hallowtech II where the tool grabs the cups from the outside. You could clarify your question by talking the specific bottom bracket first before talking about the tools. – Christian Lindig Jun 27 '17 at 8:05
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    @ChristianLindig I'm sorry it wasn't clear; my BB is the SRAM GXP that I mention in the first sentence. I can edit the title to include this also. I went this route since I thought the concept of EBB adjustment with BB tool was too esoteric. – hoc_age Jun 27 '17 at 12:04
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The short answer? No.

Threaded GXP uses the Hollowtech II style dimples for tightening, these aren't deep enough for a C-Spanner style or for a wrench the has less than 180 degrees of contact.

Even if a tool existed, most chainrings are going to get in the way, my 1X is GXP and there's not a lot of room, a double or triple is going to make this worse.

And finally, GXP works by clamping the non-driveside bearing between a flange on the spindle and the back of the crank arm. There's no preload adjustment, so tighten it down and leave it alone.

PS. What style is your eccentric BB?

  • Right, I understand that it would need to wrap around at least a bit in order to engage sufficiently; I was hoping there was some kind of eccentric or clamp wrench or something. Excellent point about the chainring; upon closer inspection the drive side (on my 1x) actually overlaps the cup, which I hadn't noticed before. The EBB is by Bushnell, and is clearly designed to be adjusted by a pin-spanner. Used one from LBS, then bought one in the same go. – hoc_age Jun 30 '17 at 0:33

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