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It seems that the extra 2.5mm spacer ring required on the drive side of outboard bearing bottom brackets is not necessary.

Shimano outboard bearing bottom brackets come with three 2.5mm wide spacer rings. On a 68mm bottom bracket, you use one on the non drive side, and two on the drive side. On a 73mm bottom bracket, you use one on the drive side, unless you are using an e-type front derailleur.

Both pedals should be the same distance from the frame when the correct spacer configuration is used. In my setup, I am using a 68mm bottom bracket with only one spacer on each side. The front derailleur is not the e-type. My pedals are both the same distance from the frame. I expected one to be 2.5mm too close without the third spacer.

Is the third spacer designed to push your drive side crank arm 2.5mm out more than the non drive side crank arm?
 

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The outboard BB style crankset is intended to have 75.5mm in-between the two BB cups. How you configure that is up to you (68+2.5+2.5+2.5 or 73+2.5). If you aren't using an E-type der. you need that extra spacer in there. If you have everything installed without that extra spacer, I predict you have side to side play in your cranks and BB.

The reason the pedals are the same distance from the frame is because regardless of BB configuration, your non driveside arm bolts to the spindle a set amount, its not adjustable.
 

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I recently got installed a Deore BB and crankset (Hollowtech II).
It developed creaking noise in about 2 months.
I dissassembled it and noticed 2 things: the bearing seal (or cover, I don't know what it is) on the driveside was damaged (a piece was missing), and it had 2 spacers on the drive side instead of one (I have a 73 mm frame).
Are those things related?
 
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