The crack of concrn is the upper most in the link below. You did not file it out. Just monitor it by eye and if it grows into the arm stop using the crank. I believe that the cranks usually fail at the pedal hole before they break here. Use that crack as a judge of the condition of the crank but don't obsess at that location it could fail elsewhere. All airplanes fly with cracks. Critical areas are monitored and parts replaced when the cracks grow to a predetermined length as part of regular maintenance. That is the price you pay for lightweight components. Brian Blum Berkeley CA former stress analyst B-2 and F/A-18C/D
Date: Tue, 17 Oct 2006 09:37:20 -0700 From: "ryan hildebrand" <firstname.lastname@example.org> To: email@example.com Subject: [CR]Filed cranks: the result [was: Stress cracks on Super Record cranks?] Message-ID: <firstname.lastname@example.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: list Message: 8
With all your encouragement and instructions I took a small chainsaw sharpening file to my cranks. All but the top "crack" shown in the "before" pictures came out with fine-grain sandpaper. I am hoping that means that they were not cracks, but scratches or some other surface flaw...?
"After" pictures are below. Aesthetics aside, what do you think? Would you ride these cranks? FYI, I'm about 5'9, 150 lbs. My daily commute is only about 12 mi. round trip, which I ride very aggressively.
Despite the apparently successful results, I am still a bit nervous. Has anyone heard of an LBS offering a crack detection service (e.g., Magnaflux)? Anyone know of liquid penetrant home kits/sources for?
Thanks much, Ryan Hildebrand Costa Mesa, Calif.
---------- Forwarded message ---------- From: ryan hildebrand <email@example.com> Date: Oct 15, 2006 7:56 PM Subject: Stress cracks on Super Record cranks? To: firstname.lastname@example.org
While cleaning my bike today I noticed some very small marks on my 1979 Super Record spider:
Is this something to worry about? Please advise!
Ryan Hildebrand Costa Mesa, Calif.
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