Dylan Solms Posted June 7, 2011 Share HiI would like to know a bit more about frame fatigue.Is it really true that alumnium frames fatigue and do the different alloys fatigue less. I've heard 7005 doesn't fatigue as bad as 6061! Does steel fatigue? P.S. GT makes this kinesis superlight frames. What is this and does it resist fatigue better?And does rigid forks in a 29er fatigue the frame more? Edited June 7, 2011 by Dylan Solms Link to comment Share on other sites More sharing options...
TNT1 Posted June 7, 2011 Share Start here:http://www.epi-eng.com/mechanical_engineering_basics/fatigue_in_metals.htmhttp://www.materialsengineer.com/CA-fatigue.htmhttp://en.wikipedia.org/wiki/Fatigue_%28material%29 There are some clever boys here, but I'd suggest read up a bit before they lose you with their engineer-ese... Link to comment Share on other sites More sharing options...
The Drongo Posted June 7, 2011 Share In short: 6 series aluminums contain more magnesium, and are more ductile. That means they are 'softer' in terms of buckling, and also 'melting' during welding. Softer than 7 series, but more flexible. Used more for frames. 7 series aluminums have a larger zinc content. They are harder and stronger but more brittle. So they are good material for components that wear, like chainrings for example. They are then all heated, or tempered to different hardnesses. Often the strength lies, not just in the alloy grade, but in the way it is extruded. ie: profile and wall thickness. eg. Double butted tube.Hollow crankarms are often stronger than arms machined out of a solid piece of alloy. Edited June 7, 2011 by The Drongo Link to comment Share on other sites More sharing options...
Johan Bornman Posted June 7, 2011 Share I won't give a thought to frame fatigue at all. A good quality frame from any of the reputable manufacturers have for all practical purposes, an infinite life. Yes, the odd heat treatment and welding flaw exists, but that's nothing to worry about. Alu is a great material for frames. A rigid fork over a suspended fork won't have any effect on the frame either. Link to comment Share on other sites More sharing options...
NotSoBigBen Posted June 7, 2011 Share If frame fatigue was an issue I would have a bike or 2 that should have fallen apart by now .... Link to comment Share on other sites More sharing options...
brussel Posted June 7, 2011 Share Johan I must disagree..I had a Niner air nine scandium that I cracked within 3 months NOT on a weld but at a bend in the chainstay Link to comment Share on other sites More sharing options...
Slowbee Posted June 7, 2011 Share was nasty ... sani2c ...... guy in front of us cracked his frame ... the top tube snapped right off the headset tube. Link to comment Share on other sites More sharing options...
_im_from_earth Posted June 7, 2011 Share Why isn't there an emoticon for "sitting back and eating popcorn"? Link to comment Share on other sites More sharing options...
The Drongo Posted June 7, 2011 Share Johan I must disagree..I had a Niner air nine scandium that I cracked within 3 months NOT on a weld but at a bend in the chainstay fatigue, or failure? Link to comment Share on other sites More sharing options...
The Drongo Posted June 7, 2011 Share Why isn't there an emoticon for "sitting back and eating popcorn"? http://wiki.urbandead.com/images/9/98/Popcorn.gif Link to comment Share on other sites More sharing options...
dirtrider Posted June 7, 2011 Share A solid steel frame made from 20mm round bar will fatigue . It just takes longer . Link to comment Share on other sites More sharing options...
TNT1 Posted June 7, 2011 Share http://wiki.urbandead.com/images/9/98/Popcorn.gif You mean:http://wiki.urbandead.com/images/9/98/Popcorn.gif Link to comment Share on other sites More sharing options...
TNT1 Posted June 7, 2011 Share This is neat, it's like the rolling resistance crap. Link to comment Share on other sites More sharing options...
The Drongo Posted June 7, 2011 Share You mean:http://wiki.urbandead.com/images/9/98/Popcorn.gif Indeed. Ta. I just don't know how. Link to comment Share on other sites More sharing options...
The Drongo Posted June 7, 2011 Share A solid steel frame made from 20mm round bar will fatigue . It just takes longer . But it could fail quicker than a 20mm round tube might fatigue! Link to comment Share on other sites More sharing options...
Tumbleweed Posted June 7, 2011 Share This is neat, it's like the rolling resistance crap. Oh, ja, was that super-formula ever produced? I remember that jmacceleri said my goldie had a good grasp of rolling resistance which sealed the argument. Link to comment Share on other sites More sharing options...
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