Fatigue cycle of Ti

[cruzroadie]

New to this discussion, but have been reading treads on and off for about 6 months. I'd like to get opinions on all Ti frames:Legend vs. spectrum vs. Seven on how many miles owners have ridden and the kind of abuse a ti frame can withstand. I'm a smaller rider 5'6" and 150lbs, currently ride a Look KG461 alternating with Orbea Orca but very interested in Ti for durability.

[Kurt]

And I mean no disrespect, but for your size/weight this is a non-issue. Buy anything you like in any color and it will be fine as long as it fits. Serotta stands behind their products, 7 has ugly rear dropouts. Ti has a specific kind of ride, based on what you have been on you might want to do an extended test with wheels/tires you are familiar with.

[Ken Robb]

I think that ti and steel have nearly infinite life as long as you never exceed their stress limits. I think that aluminum does have a finite number of stresses that a piece can stand before failing. In other words alu gets closer to failure with every cycle whether it is actually deformed or not. Having said that most frame designers arrive at a specification that allows the frame to be good for more cycles than they dem a reasonable projection of expected usage.

Do Ya feel lucky, Punk? Well do Ya? Then I'm sure you'll be fine on your aluminum frame.

[Sandy]

A very intelligent and knowledgeable man in the field said that all metals fatigue. Some faster than others.

I believe steel fatigues faster than titanium. I fatigue faster than either.

Simply fatigued,

Sandy

[Louis]

CR,

Unless you plan on absolutely abusing a frame, fatigue strength should be the very last of your considerations. Thanks to tort lawyers and the threat of lawsuits the vast majority of frames out there (and certainly anything folks hanging out on this forum would ride) are designed sufficiently well that few use strength as a criterion. Ride, cost, geometry, cool lugs, weight, whatever, all of those go above strength IMO.

Louis

[mflaherty37]

For steel and ti there are two types of fatigue, stress based and strain based. Stess based is based on nominal average stress rather than localized stresses and strains. Steel and ti generally have infinite stress based fatigue as long as the maximum stress is below a certain threshold, which say (I don't rember for sure but) it may be 12% of the yield strentth. Aluminum is affected by stress based fatique at any nominal stress level. If any of you other mechanical engineers think this is wrong you probably are right, becuase I can't rember it that well. But I do rember that aluminum doesn't have an infinite fatique life, and steel and ti have an infinite fatique life if the stresses (or strains?) are below a threshold. But a well designed aluminum frame can fatigue for millions of miles before a crack propagates through it. And steel can fatique easily if it has a sharp edge in it, causing localized strains. Unless you are obsurdly heavy and strong and ride the thing for 100,000 miles, you are not going to see any fatigue cracks. But on a 2lb seamed and cold rolled Litespeed Ghasillo, maybe - just maybe.

[sirroada]

At your weight you should not even waste prescious calories thinking about metal fatigue. At your weight this is what you should consider regarding metal fatigue:
1.) If I crash Ti or steel, I will probably be able to pick it up and ride away. If it is really screwed up it can be repaired easily.
2.) If I crash carbon fiber chances are it will break. Even if it doesn't break chances are I will gouge the resin coating. Even a minor scratch in the resin coating will create a stress riser in the frame and if it didn't break during the crash it will as soon as you hit that set of railroad tracks. I wouldn't risk my behind in that manner. Also, if a carbon frame breaks it is usually toast.
My opinion is that carbon is the fastest, most fun ride out there however the risks outweighed the benefits for me so I bought TI...never looked back.

[vaxn8r]

Also, if a carbon frame breaks it is usually toast.
My opinion is that carbon is the fastest, most fun ride out there however the risks outweighed the benefits for me so I bought TI...never looked back.
You're generalizing quite a bit. Monoqocue frames can't be repaired. Lugged CF frames can easily be repaired. It usually isn't that expensive either. I would assume the Meivici will be repairable.

I've owned CF for 8 years now and tens of thousands of miles as have many others I know. We almost all ride CF forks. I just don't see many failures. The ones I have seen would have toasted any frame made of any material.

Same as the argument against aluminum. I just don't hear about people fatiguing their aluminum bikes.

To me this is a non-issue.

[David Kirk]

Properly designed and built either material will last a lifetime. What material makes you smile?

Dave

[dgauthier]

I've been following the posts here for over 2 years, and based on the experiences of the posters, it would seem a properly constructed Ti frame, subjected to recreational riding, will last well over 70,000 miles. All the builders you mention, cruzroadie, have lifetime warranties on their Ti frames. (This doesn't mean a Ti frame will never fail, just that if it ever does, you get a brand new frame for free.) Some of the folks who actually have occasion to use that warranty have related their experiences here, and they report having no trouble getting a brand new Ti frame after their original frames have failed after over a decade of use.

[Dr. Doofus]

I get fatigued from looking at Ti

can sachs make I, Doofus, a solid* pig iron bike for a record-setting descent down Mt. Washington?


* not tubes. tubes are hollow. we're talkin rebar reinforcements, here

[Serotta PETE]

A very intelligent and knowledgeable man in the field said that all metals fatigue. Some faster than others.

I believe steel fatigues faster than titanium. I fatigue faster than either.

Simply fatigued,

Sandy


Very stately ----------------------------

[cs124]

...a record-setting descent down Mt. Washington?


reminds me...has that Red Bull downhill road bike race been run yet?

[znfdl]

I have a Spectrum Ti well in excess of 100K miles on the frame . :banana: :banana:

In my eyes Ti does not fatigue......

[Samster]

For what it's worth, I'm 5'6" and 130 lbs. I've ridden steel, aluminum and titanium (my current). I have _never_ _ever_ _ever_ tired out a frame in my entire life. I get tired of the frame far before the frame shows even the remotest sign of "failure" (having said this, I wonder how I actually know... it's like saying "turn left 1 mile before the the white church on the right.") I wouldn't worry about it. You're tastes will change and you'll want a new bike long before you pulverize your frame (unless you crash it, of course... knock on wood).

--sam

[sirroada]

[QUOTE=vaxn8r]
To me this is a non-issue.[/QUOTEI
I think that what is boils down to is this...it is a non-issue. I agree with vaxn8r. Buy what you what...ride hard and have fun. :beer:

[Jeff N.]

And I mean no disrespect, but for your size/weight this is a non-issue. Buy anything you like in any color and it will be fine as long as it fits. Serotta stands behind their products, 7 has ugly rear dropouts. Ti has a specific kind of ride, based on what you have been on you might want to do an extended test with wheels/tires you are familiar with.I don't find anything wrong with Seven's dropouts. Look pretty danged nice to me! Jeff N.