Aluminium frame crack

[JohnW]

I do think Rogerzilla's advice is the morally preferable one..............................

So do I, by a long, long way.

Regarding longevity, my oldest frame currently in use is a 1979 Pennine, which has done 11,000 miles since its 2006 respray - how many miles it had done before I can't imagine - scores of thousands of miles. My 1993 Pennine frame has done 15,000 since its 2005 rebuild, and I have a 1981 Pennine frame, which has been out of use sunce about 2005, but was in constant use from new until then - again, and it must have done scores of thousands of miles, possibly 100,000. All in 531.

I know that steel frames do fail - I was once riding alongside a bloke whose front forks broke, and he was gracefully lowered to the ground as the other, unbroken, fork blade slowly deflected - but pro-rata I would take some convincing that steel didn't have a considerably better life expectancy than either carbon or alu. Titanium seems to be a very different question, but fork material is an issue.

[mr riff raff]

Morally speaking, yes bin it.

But all I'm saying is, if you make if clear what was wrong, with loads of pictures of the fault, what's wrong with that?

I've sold a carbon wheel that had a crack in it for £100. If it split more, so be it. The buyer saved £500 on a new one and probably got it fixed for another £100 and saved £300 overall. He's happy, I'm happy.

Someone would buy the frame because of what it is, get a new headtube fitted, at great expense, and be happy. Or get it welded up by a mate during his lunch who works in an engineering firm, stick it on the turbo and be happy. Somebody could reuse it and the planet will be happy as well.

Or the bin men will take it out, stick it in their scrap pile and get £1 extra for the Christmas night out.

Up to you at the end of the day.

[mr riff raff]

By the way, I'm a salesman for a job, so generally have no scruples about selling slightly faulty, ex-display items......as long as they know about it.

[horizon]

FWIW, in the best-known fatigue test, steel came out worst for longevity!

http://www.sheldonbrown.com/rinard/EFBe ... e_test.htm

They also say:

"The fact that aluminum and carbon frames in this test lasted longer than the steel frames is not in our estimate a question of the material, but the design effort. Not the material, but its skillful use gives the result"

[JohnW]

By the way, I'm a salesman for a job, so generally have no scruples ..............................

Well, this isn't ".....slightly faulty, ex display.....", it's knackered and dangerous. Thanks for the warning about salesmen, although thankfully not all are alike.

A friend of mine, out of work, hard up, not the most knowledgable cyclist, but extremely strong and fit, recently had a pair of wheels given, as being "well worn, but will put you on until you can afford some more". 1500 miles later, and about 70 miles from home, the front one developed a deformity in the rim. He didn't say anything to us, but stopped using his front brake because of the uncomfortable judder, taking the view he'd "sort it when he got home". Eventually one of us noticed his non-use of the front brake, and we stopped and looked at the wheel. The outer edge of the rim had deflected in one place by about 2mm, and there was a slit in the rim at that place, about 25mm long, into which one could insert one's thumbnail. If he'd used his front brake on a long downhill, he'd have split the rim completely and probably killed himself.

He walked into Settle and caught the train home to Halifax, and lives to ride another day. The wheels were given (given, not sold) to him in good faith, but he over-rode them in inoccent ignorance and could have died as a result.

Anyone who knowingly sells something faulty has a very big responsibility - and when I say faulty I don't mean shop soiled like, say, a scratched mudguard, I mean functionally faulty like a cracked frame, is being negligent and irresponsible - and "buyer beware" does not take away culpability.

mr riff-raff - I haven't misquoted you by selective omission for nothing.

[JohnW]

FWIW, in the best-known fatigue test, steel came out worst for longevity!

http://www.sheldonbrown.com/rinard/EFBe ... e_test.htm

They also say:

"The fact that aluminum and carbon frames in this test lasted longer than the steel frames is not in our estimate a question of the material, but the design effort. Not the material, but its skillful use gives the result"

Returning to longevity - my oldest frame, although little used nowadays, is the 1972 Pennine that I did a bit of time-trialling on.

My oldest frame in regular use, my 1979 Pennine, did 750 miles in June - it's still in that kind of regular use - not pensioned off and displayed on the sideboard.

Now, show me a carbon or alu frame anywhere near as old as that!

I, and many of my cycling colleagues are riding frames from the seventies, before carbon or alu frames were dreamed of. How can carbon and alu frames be deemed to claim the longevity high-ground, when there are probably many, many thousands of steel frames, built decades before carbon and alu frames were ever invented, and have been in regular daily use for all those years.

How is longevity defined?

[glueman]

One difference is steel frames deteriorate whereas aluminium ones break. If a high quality steel frame falls apart as in the case of John's friend's forks, it's mostly because the owner hasn't kept an eye on a growing fault.
Of course the main difference is the technology to fix steel is widely available unlike other materials, though whether it's cost effective is another matter. Unbranded alloy road frames verge on the disposable, pricewise.

[BTP]

One difference is steel frames deteriorate whereas aluminium ones break.

I think that's a bit of a generalisation.

Steel does have a finite fatigue (endurance) limit, whereas aluminium, strictly speaking, does not.

But the failure mode for both depends more on the frame tube dimensions, whether it is stressed due to impact or due to long term cyclic stress, etc etc. I've seen evidence of broken steel bikes and bent aluminium ones - it depends on several factors.

In this case I suspect that the gauge of the Al used was possibly on the thin side at the top and bottom of the head tube. Or it could be part of a flawed billet. Or it may not have been heat treated properly or not properly faced.

Cheers

[JohnW]

I've brought this forward for neilbob to have a look at.

You're not alone nielbob.