I noticed that the right arm (drive side) of the Shimano Deore FC-M591-S Hollowtech II is getting loose. The right side has the axis attached to it as shown in the image.


When I take off the left arm (non-drive side) I can see the axis moving up and down within the frame. I tried tightening the connection with the crank lid tool which helps somewhat. The set is from April 2011.

  • What do you mean by 'axis'? – Holloway Oct 21 '14 at 8:59
  • Maybe "arbor" is the correct word? – JJD Oct 21 '14 at 9:47
  • Do you have left and right confused? Right is drive side and has the 'axle' or 'spindle' attached to it. Could you rephrase using DS (drive-side) and NDS (Non-drive side)? – mjsqu Oct 21 '14 at 9:55
  • @JJD in my head that's a wooden arch. Spindle or axle maybe (the part that goes through the BB) or crank (the part from axle to pedal). – Holloway Oct 21 '14 at 10:02
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    As @mikes alludes, if the long grey cylindrical metal bit is wobbling around inside the silvery cup thingies, then your bottom bracket is busted – mjsqu Oct 21 '14 at 10:27

Two things, if you take off the drive-side (R) of the crank and the 'axis' moves while you hold onto the chainrings, then the crankset needs replacing (or at the very least, this drive-side part).

Secondly, if there is too much play in the 'axis' while it is still in the bottom bracket, then the bottom bracket cups are probably worn out and will need replacing. I've heard it is possible so service these cups by taking off the plastic rings, but never tried it myself. The cups are usually inexpensive.

Square taper bottom brackets usually last longer but are heavier.

External Bottom Bracket

I'm assuming these are already attached to your frame, so you'll need a tool like this too:

Hollowtech tool

  • Can you add pictures of the parts I should replace? This would help me to understand in those case where I am not familiar with the technical terms. – JJD Oct 21 '14 at 11:39
  • Done, it's better if you can borrow the tool from someone, or get a shop to replace your BB if you don't have the tool and only think you'll do this once. – mjsqu Oct 21 '14 at 13:16

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