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 Post subject: Two pieces of metal
PostPosted: Sun Oct 21, 2012 9:59 pm 
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Have a look at this pair of cradles from a Campag. Nuovo Record seat post. A beautiful casting, (or is it forging?) Elegant, evocative, even iconic - that's why I dig this stuff - my interest is aesthetic more than functional. I mean, I like to go fast... sometimes.., but I'm never going to be going fast enough to need an aerodynamic seatpost. :)

Anyway, look closely at these two bits of metal...... Can you see what I can see? Looks like somebody (maybe me) should have followed the advice implied by my user-name! :oops:

Being something of a bottom-feeder, I usually get hold of stuff, if I get hold of it at all, after it's been f--ked up by a few previous owners, not that I'm not equally capable of f--king up stuff myself. :) Also, a lot of this stuff was of course designed at the outset to be as light as possible, meaning that it exists pretty close to the edge in terms of structural integrity. I was always amazed that these two flimsy looking pieces of aluminium alloy could, even when they were brand-new, be expected to support a rider ... Thirty years of metal-fatigue later I reckon their road-going, load-bearing days are over. Personally I got about ten miles out of them, and I'm a lightweight geezer who gets up outa the saddle for rough road. Now I guess they could live on as a pair of earrings. I've never owned one of these seat pins from new, so I'd be interested to know how often they broke back then. I suppose the alloy bolts (mine are steel) might sort of prevent you from over-tightening the whole assembly because hopefully you'd strip the threads before you cracked the cradles, and bolts are often replaceable.

That got me ruminating about Eroica. In a paranoid sort of way, (which is probably my default setting.) Imagine an event where you take several of the most fragile bicycles ever conceived, and persuade their owners to ride them over some really bad roads with a gutful of Italian food and wine. I wouldn't be surprised if the whole event was funded by the bike industry, intent on breaking as many old bits (and their devotees) as possible so we have to buy some new ones. But I don't know.. I've never been to Eroica. Using the event to sell more old stuff more or less guarantees that the same people will be back next year with another lot of components to fatigue as much as possible before selling them to a mug like me. :) All of this makes me wonder about my subconscious motivations for being interested in old bikes, especially old lightweights, in the first place...

Of course the flip-side to that is that these bikes should be ridden...It is arguably better that they should fail in honest service than that they become a static display piece in someone's gaff, you just have to trust them to let you down gently if or when they do fail. I suppose you can meet them halfway by looking out for just such little cracks as can be seen in the photo above.

So the point of this thread is: Show us your dangerous bits. Points (and patronage) can be awarded to any component manufacturer whose products don't appear in this thread.... And I bet you it's the ones that are no longer in business, too. Does anyone believe that crap about the 'market' providing better products through competition between rival manufacturers? Not me.

But maybe it's not entirely the manufacturers fault. Perhaps certain components attract certain types of people: You'd expect heavy people and heavy spanner-torquers to go for solid over-engineered stuff, and lighter folk to be attracted to daintier stuff, but the vagaries of human psychology being what they are, It's just as likely that exactly the opposite set of relations can be found. Also, just because someone is built like a brick shithouse it doesn't mean that they habitually over-tighten bolts, and someone who looks like the wind might blow them away can at the same time be an extraordinarily efficient thread-stripper and component-cracker. :) No caricatures or stereotypes here.

Just thinking out loud really. A meditation inspired by two (cracked) pieces of metal. Telling you nothing you didn't already know.. Any thoughts?.... Or bits?


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 Post subject:
PostPosted: Sun Oct 21, 2012 11:37 pm 
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http://www.retrobike.co.uk/forum/viewto ... ?p=1585771

have a look at my copper plated bike a few posts in........I have drilled the seat post with big holes (campag record) to lighten it to the point where the guy holding the bike at the start of TT's got worried LOL

Shaun


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 Post subject:
PostPosted: Mon Oct 22, 2012 2:29 am 
Gold Trader
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I, as I should imagine nearly 99% of owners did snapped the plate that secured the handlebars in my Cinelli 1R record stem :evil: :oops:

Also snapped at least 2 clamps on Mavic front mechs before I found they were not designed for 531 tubing (or so I was told) :twisted: :oops:

Cracked Modolo Orion levers, Exploded a Mavic MA40 Rim (snapped on the joint with an almighty bang), and completely destroyed a YST sealed bottom bracket (broke in two :shock: :shock: ).


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 Post subject:
PostPosted: Mon Oct 22, 2012 9:00 pm 
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Quote:
........I have drilled the seat post with big holes


That's not a seatpost, it's a flute. I bet you got some haunting melodies out of that during a windy time-trial :)

Well, we already seem to have two different categories of dangerous bits:

A) The ones that should perhaps have had a bit more thought put into them at the design/production stage, maybe beefed up a bit at critical points, acknowledging in fairness the fact that no manufacturer was, AFAIK, saying: "Ride on this for thirty years".

B) The ones we took a file and drill to in an attempt to either lighten them, or make them resemble more closely the horrifically expensive stuff being used by our idols. (usually both)

Also, occupying a sort of middle-ground between A) & B) are bits that needed filium and/or drillium to relieve stress created by poor design....like the campagnolo NR/SR (and the numerous copies) RH crank/spider edges where you can oftentimes find a little crack developing.

Any more? all candidates welcome!


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 Post subject:
PostPosted: Wed Oct 24, 2012 7:29 pm 
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Difficult to tell in the pic, but those look like edges in the moulding/casting.
I can't imagine what stress would crack them, do the marks go right through?


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 Post subject:
PostPosted: Wed Oct 24, 2012 8:08 pm 
King of the Skip Monkeys
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I may have a spare set. Maybe, possibly...


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 Post subject:
PostPosted: Wed Oct 24, 2012 8:38 pm 
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I do up that seatpin quite tight and I haven't had any breakages so far and it's rock solid. Perhaps it wasn't tight enough and cracked from fatigue, like spokes that are not tight.

The only part I've broken and it's my fault is the Campagnolo qr "housing" where the lever fits into. I had the adjusting nut too tight and when I tried to close the lever, the thing cracked.


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 Post subject:
PostPosted: Wed Oct 24, 2012 8:52 pm 
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The lines on the seat cradles are moulding lines, not cracks. I have a SR post with the same features.

These days, mechanical designers have the benefit of 3D design packages with in-built stress-analysis to ensure that stresses on components are minimised whereas up to 20 years ago it was more an empirical process and often a case of make a prototype, see if you could break it and if it survived, that became the productions standard (I know, that's what we did!)

The craze for drillium wasn't based on any science or engineering, often a case of getting the milling machine to remove much of Vicenza's finest and if/when it broke, you bought a new one!


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 Post subject:
PostPosted: Thu Oct 25, 2012 8:36 pm 
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With respect, these certainly look, and feel, like cracks to me, and yes they extend over the face that butts against the pin and up inside the 'bore'. It is difficult to work out how they cracked, because functionally I guess the whole bottom semi-circle of the casting could be removed and everything would still hold together under tension. In that respect maybe I am worrying about nothing..

I think fiks may be right that someone has been riding this pin with the bolts loose. :x It was NOT me! Honest...


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 Post subject:
PostPosted: Mon Oct 29, 2012 10:31 pm 
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I spent most of today messing about with hacksaws drills and files and managed to produce this, which is intended to fulfil the same function as those two pieces of metal. It's looking quite promising.....

Keep those f--ked up cranks, you never know when you're going to need a bit of Dural.... :wink:


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