Shimano external BB bearings… how tight?

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  • Shimano external BB bearings… how tight?
  • ormondroyd

    Am I right in thinking the BB bits of Shimano Deore cranks should be screwed pretty blimmin tight to the frame? Don’t have a torque wrench to hand.

    Not too tight but just enough. You don’t want to be shafting the threads on the frame by hanging off the spanner. Never used a torque wrench but when the spanner starts to hurt your hand then that’s enough.

    I always run mine just a little bit past finger tight. You should get a feel for it


    I cant remember the specific torque, but its not that high. The Shimano spanner that you fit them with has a short handle which should limit the torque you can apply.


    really? i assumed the length of the BB spanner was an indication that it needed to be quite tight, nothing daft, just sensitive feeling when you’d reached the end, and a tweak on.

    unless youre talking about the preload cap?


    A good coat of copper grease and then tighten til they are snug then when both are in place I just nip them up not swinging on the shimano tool but a firm pull, as said you will get a feel for it , but always use grease, dry fine threads are not good, I also put a sheet of plastic over the bottom bracket so the tool does not dig into the alloy.


    Do they not say something like 40Nm on the cups? Or is that the arm pinch bolts? I do them up to what I would refer to as palm of hand and wrist tight as opposed to fingers or whole arm, shoulder or hang off it (increasing order of tightness).

    I use the shimano spanner above and put a decent smear of anti-seize (or grease that is safe for plsastic/rubber) and tighten them gently with the spanner in the palm of my handjust using my wrist for leverage and tighten up with my palm open.

    I then give them a short sharp nip up of about 1/8 tur again with my wrist but gripping the spanner gently. No forcing it round, no hanging off it and if you remember to always hold the tool gently you won’t get carried away.

    For the plastic pre-load nut make sure the drive side is fully pushed home – do not try and use the pre-load nut to pull the shaft through the bearings. Use a gentle tap of a rubber mallet (or similar)holding the bb area in your other hand. Then just nip up the pre-load cap with your finger tips and do up the arm clamp bolts – preferably to the specified torque.


    Thanks! Sorted. The mallet tip was particularly useful 🙂

    Or is that the arm pinch bolts?

    40Nm for pinch bolts? The clues in the name

    esher shore

    the 2 pinch bolts are fitted around 12-13nm


    cups – coppaslip and nice and tight in the frame – no need to totally haul on the spanner but get it nice and tight

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