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I'm trying to swap the cranks on our Thorn tandem and would like to know what kind of crank extractor (if any) I need for the job.

Is there a way to tell from this photo, before I've taken it all apart?

EDIT: Photo updated after cap removed (sorry it's a bit blurry). Centre has a thread, is that what I'd screw into and pull?

Crank centre, cap removed

For example, Thorn list several crank extractors.

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Remove the crank bolt and dust cap. That is what one would really need to see (i.e. the end of the BB spindle... square, spline...) – WTHarper Jan 26 '14 at 21:09
It's probably an 8mm hex bolt with the black plastic cap attached. It should come right out leaving the crank in place. – WTHarper Jan 26 '14 at 21:10
Thanks, yes I tried that. Photo updated. The centre is a screw thread, though I can't tell which direction. – James Bradbury Jan 26 '14 at 21:30
Uh, obviously the screw thread is the same as the cap (standard kind of righty-tighty, lefty-loosey). – James Bradbury Jan 27 '14 at 9:13
up vote 5 down vote accepted

You will need a specialty tool referred to as a crank remover or crank extractor. A Park Tool CCP22 or something similar. I would suggest considering the Park Tool CWP7 or equivalent as it offers increased flexibility. While the CCP22 is suggested for square shaft interface the CWP7 will do square, splined and octolink. While you only need the square type now the universal design of the CWP7 may come in handy later.

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Yep, the important thing is that the large thread of the extractor body match the large thread the cap screwed into. I think the CWP7 is the one that has two different sizes to handle most square cranks, and it's been a good tool for me, through two bikes. – Daniel R Hicks Jan 26 '14 at 23:20
Thanks the CWP-7 did the job nicely on what turned out to be square-tapered cranks. – James Bradbury Feb 6 '14 at 12:59

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