I have a near new bike only ridden a handful of times, it has a self extracting crankset I believe which uses a pin spanner, the drive side crank is now slightly moving side to side. This isn't happening on the non drive side crank, why is this? How do I tighten it and what tool do I need? See pictures below.

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  • 1
    In addition to @WeiwenNg's answer, you may find you need to use a thread locking compound like blue Loctite no matter how tight you make the retaining bolt. Commented Aug 19, 2021 at 17:01
  • We can see clearly a clockwise arrow on the inner race saying "tight " You need to keep trying hex tools till someting engages with the visible splines. Try a 10mm and see what happens?
    – Criggie
    Commented Aug 19, 2021 at 20:48

1 Answer 1


Chances are you tighten the crankset using an 8mm hex wrench. I'm not sure if any cranks take 10mm wrenches, but I believe most or all are 8mm.

I'm not sure exactly what the object with the pinholes does. On older self-extracting cranks that I'm familiar with (square taper or Shimano Octalink), the self-extractor had pinholes in it. When you undid the hex bolt that secured the crank, the bolt would push against the self-extractor and push the crank out. In that arrangement, the bolt was basically a captive bolt unless you took out the self extractor with a pin spanner. Speaking of that, a crank needs to be tightened down pretty hard - 40 Newton meters is a common spec I've heard, and it's quite hard, and it's definitely much more force than you could possibly exert with a pin spanner.

You do want to tighten down that crankset as soon as possible. If it's ridden loose, you could be stripping the splines on the crank that keep the spindle mated to the drive-side arm. If you rode a square taper crank with one side loose, after too long you'd deform the broached opening in the crankset (the square taper spindle was almost certainly steel, and if not that it was titanium, either of which are harder than the aluminum that cranks are made of, so it would be the crank that died). A prior answer alluded to that, but it was presumably deleted because this isn't a square taper crankset, and we can't be certain that this has happened yet anyway.

  • Thanks, I will go try with a hex wrench, I havent ridden it like this at all.
    – Charlie
    Commented Aug 19, 2021 at 16:31
  • I tried using an 8mm but it simply slided through, I looked on park tools youtube channel and I saw Calvin mentions using a pin spanner or 8mm on mine there is no fitting for an 8mm.
    – Charlie
    Commented Aug 19, 2021 at 17:05
  • @user57888 Well, if 8mm slid through, then it’s probably a 10…
    – MaplePanda
    Commented Aug 20, 2021 at 0:20
  • I’m Googling. 9mm hex bolts exist, and there are some applications in the automotive space. But they’re rare. In bicycles, I don’t know of anyone using 9mm for anything. No tool sets have 9mm wrenches. So, it more or less has to be 10mm unless the 8mm key fit really, really loosely in the bolt.
    – Weiwen Ng
    Commented Aug 20, 2021 at 0:29
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    The pin spanner holds the cover over the crank-bolt in place. The crank is tightened to the spindle with that 8 or 10 hex. When untighening the hex bolt pushes against said cover to extract the crank.
    – Carel
    Commented Aug 20, 2021 at 11:41

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