Fixing a Victorian

Woz

Old School Grand Master
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Looking at this again. It's so elaborate, to the point of being over engineered for solely aesthetic reasons? Differentiate your product with a feature? It's not a cheap thing either. Is this one reason for the oversized tubes perhaps?

The seat-post diameter, taper angle, depth of the collet thingy, thread length, thread pitch and nut must be incredibly precise so it doesn't look a bodge, nor fail on installation (lug split or threaded, nut head sheared off = frame buggered), nor seize up, nor crush the seat-post, nor wobble about, creak, etc. etc.

Like you say, that collet thingy looks captive, but it wouldn't make sense to insert it until the frame is really finished and ready for bike assembly.


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grantoury

Dirt Disciple
I am enjoying the depths this thread explores. The frame throws up so many questions, even from a historical point of view it is special. But I am not as surprised at the ingenuity and even over engineering of it. I think it shows they took great pride in their work and maybe would even choose to go the difficult route to prove their skill. In a racing environment they would expect this to be under close scrutiny. They had something to prove. It reminds me that the bicycle is a unique invention, its development driven by some great minds.

Maybe I am gushing. I like a Porsche too ;-)
 

Mickeyspinn

Senior Retro Guru
Looking at this again. It's so elaborate, to the point of being over engineered for solely aesthetic reasons? Differentiate your product with a feature? It's not a cheap thing either. Is this one reason for the oversized tubes perhaps?

The seat-post diameter, taper angle, depth of the collet thingy, thread length, thread pitch and nut must be incredibly precise so it doesn't look a bodge, nor fail on installation (lug split or threaded, nut head sheared off = frame buggered), nor seize up, nor crush the seat-post, nor wobble about, creak, etc. etc.

Like you say, that collet thingy looks captive, but it wouldn't make sense to insert it until the frame is really finished and ready for bike assembly.


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Without doubt it's aesthetic but I think the weight of collet and nut versus extra material around seat tube material for seat bolt and the bolt itself could possibly be lighter! A collet has a more total clamp around a circumference than a split clamp...it would also mean the seatpost could be a thinner wall tube!
Collets do need to be treated with a bit of respect in this instance it'd be a mare to solve if it got fouled up 🙄
It's possible the collet has been put in after the frames finished ....getting it out ..hmmm I wouldn't want to try....could all go horribly wrong!
Hopefully when nabeaquam is back from his jolly we can get a look at the nut and seatpost....see what treats we find their 😁
 
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Woz

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Something to mull over.

This is one scenario how the collet could be kept captive. Basically two tapers. One for clamping the seat-post, and another for insertion.



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Woz

Old School Grand Master
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I have my reservations with this scenario though.

From experience of dealing and fiddling with bits of all sorts, like vintage cameras, computer printers etc. I'm inclined to think optimising things for assembly and non serviceability is something that doesn't make a corner stone in the USA. One reason I like to fiddle with USA made stuff is that it is generally straight forward. You can practically rebuild a Singar sewing machine on instinct. Post war Japan stuff on the other hand is something else. They embedded things in design to facilitate assembly and production so you end up with a sub-component that is a mind-f\/ck to isolate. In the area of early electronic and miniaturisation mechanical engineering they stormed ahead (think Walkman, think Betamax, think Canon, think, Nikon) and in bike terms think Shimano.
 

Woz

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The more probable scenario I think is forget the lower 2nd taper as I call it. If the length of the slits, the diameters are well studied and the length of the collet too, I see the most sensible thing from a weight perspective is to insert it through the BB and up the seat-tube with some cord. Using the principal taper, and giving the cord a quick yank to set it over the lip and make it captive.

The BB is massive in diameter which makes me think this is the way.

I'll wager now for the hell of it, for fun really, I don't think the seat-tube is plugged at the BB. I don't think the BB shell is like we expect and used to in terms of casted structures. I reckon it's skinny whittled down to nothing and uses an internal lug structure which we don's see.
 
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