Crank Failure

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Crank failures

Race Face Turbine LP crank failure.


From as of 2007/06/26. Accompanying text:


I was innocently Just Riding Along minding my own business up a slightly steep but not awful hill [...]. Blam-o it felt like my foot slipped out of my pedal but when I went to clip back in my foot felt a little heavier and my pedal wasn't where it was supposed to be (well I guess it was since I was still clipped into it).

Let's wait and see how Race Face are on this warranty issue, I've had bad luck with them in the past. They refused to warranty a next lp crank that broke in a similar fashion, although the carbon fibres held that to the crank arm, but they did give me a crash replacement on it. They also failed to warranty a XY seat post that snapped as well :(

I'll admit I kinda crank hard on them since I never use my granny gear, but that's likely not the cause and I can't even think of a time when I've bashed them good enough to do any damage. [...]

Note darkening indicating failure propigated from the right side of the picture to the left.

Note the failure is away from the spider.

Note the crank has an I or C section, compare to older cranks.

Unclear from picture, but failure may have occured in an area of reduced dimensions and/or bend in the arm used to give angle clearance.

Cranks used on a dual-suspension bicycle. Rider reports doing "a lot" of jumps and drops but none over 1.3 metres.

Same rider, photograph dated 2002/07/21. From as of 2008/02.

(Click to enlarge.)


Note failure is in center of arm away from most features, but at the edge of a "window" in to the hollow crank, and in an area of relatively thin section compared to the "window" closer to the spider.

Used on a bicycle with no rear suspension; mostly small/no jumps; rider weight 72kg-82kg.

See also FAIL-051.html.