[CR]Steel Cranks

From: "brian blum" <brianblum@hotmail.com>
To: classicrendezvous@bikelist.org
Date: Tue, 10 Jul 2001 19:42:14
Subject: [CR]Steel Cranks

Actually Steel has an Endurance limit, a level of stress below which the steel will not fatigue. Aluminum has no such ENDURANCE LIMIT and will accumulate damage at any stress level and eventually crack though practically this damage is very small at low stress levels. This is because the material exhibits a hysterisis loop in its stress/strain curve absorbing energy in the material(damage) as it unloads which along with overly stiff tubes could be part of the non resiliant dead feel of aluminum.

Date: Mon, 9 Jul 2001 21:25:58 -0700 To: Joseph Bender-Zanoni <jfbender@umich.edu> From: Monkeyman <monkey37@bluemarble.net> Subject: Re: [CR]Cottered Crank Safety Cc: classicrendezvous@bikelist.org
>Anyone hear of high quality steel cranks breaking?

Um. . . yes. We actually talked about this last month when a bike went up on Ebay that had a broken steel crank. I've personally brazed on 2 pedal eye replacements in the past. Steel cranks do break, good materials never overcome poor design. I've also seen a few pair of modern broken steel cranks too. Steel has a fatigue limit too it's just not as low as aluminum. I do believe that well designed steel cranks are much less likely to break though. enjoy, Brandon"monkeyman"Ives