I can feel so laterial play when grab hold of the crank arms then wiggle it side to side. I discovered the lock ring was very loose. So much so i could turn it with my fingers without any effort.

When I tightened the lock ring just by hand, the play went away. I loosened it then it came back.

Does this mean my bb is unscrewing itself from the frame and i need to tighten it up?

Is this a job for a newbie home mechanic to attempt?

enter image description here

  • Check if there is a bike co-op in your area. They will probably have tools that you can use for a small fee or possibly even for free. If it's just a one time fix, it probably isn't worth buying the tools.
    – Kibbee
    Commented Sep 20, 2016 at 20:12
  • You can stick a screwdriver in the notch, angled to one side, and tap it lightly with a hammer. But you need to tighten the cup first, beyond what you can do with your fingers. The screwdriver trick will work with that, though it gets kinda ugly. But the right Park Tool wrench (HCW-11) to tighten it correctly is only $20 on Amazon, and actually less at my local bike shop. Commented Sep 21, 2016 at 1:35
  • yeah if you mean Edinburgh bike co-op, they closed them down very recently. Actually little annoyed my dads bike has some issues and it's still under warranty.
    – Ageis
    Commented Sep 21, 2016 at 11:17

2 Answers 2


Loosen the lock ring, then tighten the bottom bracket cup until the play goes away and the crank moves smoothly. Then hold the bottom bracket cup in place and tighten the lock ring.

There are special spanners you can buy for this or you can use an adjustable spanner to move the bottom bracket cup and a screwdriver tapped gently with a hammer to tighten the lock ring. You may have to improvise further with your choice of tools. You may also need an assistant.

A newbie mechanic should have no problems doing this. If you don't try you won't learn.

  • yes that is my mantra but I end up breaking stuff 95% of the time!! LOL
    – Ageis
    Commented Sep 21, 2016 at 11:20
  • 1
    @Ageis focus on the 5% :-)
    – KeithWM
    Commented Sep 21, 2016 at 11:32

The adjustable cup can be adjusted with an adjustable wrench or regular open-wrench set. If they are too thick and you don't want to take off your crank arm, you might need to get a cone wrench.

And while you can tighten the lock ring with the screwdriver tip, I find that this has a tendency to cause damage to the lock ring.

One of the joys of doing your own work is accumulating cool new toys.. err.. tools. So I'd splurge and get the proper tool. Cone wrenches are pretty cheap.

The lock ring wrench is a little more expensive. Here is the cheapo version, XLC Adjustable Bottom Bracket Spanner ($5-8):

XLC Adjustable Bottom Bracket Spanner2

Your local bike shop can provide you with options and make sure you get the right wrenches or you can shop at a discount bike parts shop. There are very good tips on how to adjust your bottom bracket at Sheldon Brown's site: http://www.sheldonbrown.com/tooltips/bbadj.html

  • 1
    But tightening only the lock ring is not sufficient. The cup must be appropriately adjusted first. Commented Sep 21, 2016 at 21:47

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.