The crank shaft and axle are a single unit, so the whole thing needs to be removed.

Diameter is approx. 50 mm and a spanner/wrench/screwdriver needs to be able to grip both notches and twist without being blocked by the crank arm.

Any suggestions?

Nut is from an exercise bike


That would call for a pin wrench.

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  • But if you don't have a pin spanner wrench, can you loosen it by placing a screwdriver in one slot at an angle and tapping the end with a hammer? – Jim Stewart Jul 28 '20 at 21:58
  • 3
    @JimStewart if you are lucky and it’s not too tight, but it’s also easy to damage that ring... – Solar Mike Jul 28 '20 at 22:37
  • Yeah, the screwdriver approach can work but it is a recipe for frustration. It's harder than it sounds to get enough force in the right direction to move what may be a tight and stuck piece. – isherwood Jul 29 '20 at 12:38
  • Thanks all for the tips. I tried the screwdriver approach in the first instance, but as @isherwood suspected, this was a road to frustration. Currently waiting on my pin wrench to arrive in the mail. – Ciaran Jul 30 '20 at 17:17

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