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The pedal snapped off the crank arm and there is a portion of it left inside. How do I dig this out and replace the pedal?

closed as unclear what you're asking by Grigory Rechistov, David Richerby, Criggie Mar 1 at 8:20

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    Please provide a clear and well lit picture of it. Thisv will tell us much more on such method is possible than descriptions. Also, is it on the drive side or on the non drive side of the bike? – gschenk Feb 26 at 7:21
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    Usually by buying a new crank. For steel cranks, the pedals are usually next to impossible to remove once you've used them for a year or so. You may get lucky with a lot of creeping, rust dissolving oil, and an equal amount of brutal force, but I've had to resort to destroying the crank quite a few times. – cmaster Feb 26 at 7:49
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    There's a non-zero chance the thread in the crank arm has suffered some level of damage too. If you plan on reusing the crank arm, be careful not to damage the thread more or you may need to repair it (chase/retap) or at worst heilicoil the hole. You'll need a pair of replacement pedals as well. – Criggie Feb 26 at 9:20
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    Why this attracting 'unclear what you asking' votes? Seems pretty clear to me. Could be improved, sure, but it's not close worthy IMHO. – Argenti Apparatus Feb 26 at 20:56
  • It's unclear what has broken off where. Has the threaded end of the pedal shaft broken off, or something else? If the former then the obvious approach is to remove the crank arm and have a reasonably skilled machinist drill it out. May damage the arm in the process, though, or it may already be damaged due to the motion of the failing shaft. – Daniel R Hicks Feb 26 at 23:16
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If there is a substantial length of axle sticking out of the crank the easiest approach is to remove the crank, grip the axle stub in a vice and turn the crank to unscrew it. You may also be able to use a vice-grip wrench instead of a bench vice. Remember that the left crank has a left hand thread.

If there is less axle sticking out: file a couple of parallel flats for an adjustable wrench. You might be able to use a Dremel or similar rotary tool to grind a slot for a large screwdriver.

If the above approaches do not work, the axle will have to be drilled out.

Steel pedal axles are far more robust than aluminum alloy crank arms, so hard to imagine the crank is not damaged also. If the pedal axle thread looks damaged at all, toss the crank - unless you want to attempt re-drilling and tapping it with a helicoil. If the crank is bent or cracked it needs to be replaced.

  • Since pedal axles are hardened steel it will be very hard to drill it out. – Carel Feb 26 at 14:54
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    @Carel not necessarily, there are different degrees of hardening and axles can be hardened more at the bearing surfaces. Axles shafts can't be too hard or they be too brittle. That said, OP will probably chew up a pile of drill bits if they attempt this. – Argenti Apparatus Feb 26 at 14:59
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    What about a bolt extractor? – Rider_X Feb 26 at 17:39
  • @Rider_X Oh yeah, those too. That's probably the best approach if there is no axle sticking out of the crank arm. – Argenti Apparatus Feb 26 at 18:10
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    Sooner rather than later, I can see it getting to the point that a replacement would be faster and easier and maybe even cheaper. – mattnz Feb 26 at 19:08

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