--Original Message-- From: Michael Butler<email@example.com> To: "Norman Kilgariff" <firstname.lastname@example.org> Subject: RE: Clarification on Bi-Laminates? Norman, Brilliant fascinating reading look forward to reading the next postings. The term sleeve might be a little confusing as most of the bi-laminates I have witnessed before construction are cut out of flat sheet and then formed around the frame. Aka Tom Board and the later Paris company when he made the "New Galibiers" this was exactly the same method as used on the earlier Rensch produced Galibiers, or Bill Philbrook when he made our tandem in 1972. Am I right in saying that all bi-laminates start out as flat sheet and then become sleeves after silver soldering or are some fashioned as true sleeves first from oversize tube which would be a true sleeve. Perhaps someone could answer this query? --Original Message-- From: Norman Kilgariff<email@example.com> To: <firstname.lastname@example.org> Subject: [CR]CR [bi-lam] My version 1 of 4 I will make 4 posts, 1 day apart c 1000 words each. After the fourth would you please make any questions easy ones, as they are my favourites.
Let me give you my explanation, but where there is light Claud pulls the plug. Thanks to Claud, we now face conflicting models of bi-lamination:
Like many UK builders, Harry Rensch sought Continental ideas. He saw sleeved frames in Paris during 1935 and introduced his own version to the UK pre 1940, but gave no special name to the construction method/type. So Harry did not invent this, he essentially copied it and introduced it to the UK.
Claud Butler adopted a very similar idea/method and advertised his first example, an Avant Coureur by April 1948. But Claud seized the opportunity to announce this was a whole new class of frame. Currently frames were either lugged or lugless (a new class probably introduced in the 30's). Claud decided that his new construction type need not fall into either of these classes, it was significantly different, he therefore created a brand new class. (ref: CB 1951 cat cover says choice of welded, brazed or the now world-famous CB bi-laminated frame construction). Here, in today-speak, brazed means lugged and welded means lug-less.
His Avant Coureur was lug-free, so it had all the benefits of a lug-less frame, variable geometry etc. However lugless frames need only be tubes stuck directly together. By adding sleeves to the tube ends he could enhance both STRENGTH and appearance.
The main loads on a cycle tube are at the ends, hence butting, thicker at the ends, so the metal is where you need it. Tube strength depends on the steel quality, tube wall thickness and the cube of the tube radius. The sleeves increase tube-end thickness (531 walls are only 0.9mm thick at the buts) and the extra metal goes on the outside, increasing its radius too. The braze that provides the bonding between the two layers is not as strong as the inter-atomic bonding of the steel, but it is still strong. To prove this Claud sent a sample to the National Physical Laboratory for testing (I wonder if it had thicker sleeves than normal, like Mick's Paris). So he sells it on 'strength', your eyes tell you it is pretty.
The name he thrust forward for this new class was bi-laminated (two layered). Lugless but does not look it and significantly stronger. Let me point out prematurely, that fancy lug extensions will add approximately zip to the frame strength.
Claud simply asserts; here is my new frame, it is unlike the current lugged or lug-less, I call the new type/method bi-laminated construction, it is extra strong etc. Of course, Claud has no authority outside of his own business. He could not force Paris's or anybody else to accept this name for theirs. Paris's could adopt their own name "Parisated" or whatever. We would have two names for a pretty much identical set-up, like IDE and ATA hard drives, because neither company wants to appear subservient to the other.
But this duplication of terms did not happen. The name thrust forward was bi-lam and it was generally embraced. As Paris's frames were closer to bi-lam than lug-less, Claud was deemed not to be the first to use this type of construction.
This put Paris Cycles in a funny position. They were the first folk in the UK to produce a bi-lamination type of frame, yet they have absolutely no special position in stating what is or is not a bi-lam. It is only because some of Paris's frames conformed closely to Claud's bi-lams, could they claim they were the first in the UK to make this type of frame. Anything Paris's made, which did not conform to Claud's model of what constituted a bi-lam, ain't a bi-lam. Same for Holdsworth and Hetchins et al. If lug extensions qualify as bi-lams (they don't), then Holdsworth were making bi-lams before Claud too, but (unlike Paris's) they had a name for them. But I jump the gun again.
I repeat, Paris's, despite bringing the basic idea to the UK, have no special position at all in defining what is and is not a bi-lam. Claud defined it initially with the models he sold as bi-laminations. Claud is no longer here; new methods and materials have evolved. We can DESCRIBE Clauds 1948 Avant Coureur all right, but when new frames appear we have to know which of the features DEFINE a bi-lam so we can say whether the new machine is a bi-lam or not. Does it have to be fillet brazed or would modern mig welding do? are carbon tubes OK? Cycledom must decide on what defines a bi-lam frame, and this is where our troubles begin.
Next post tomorrow. Norman Kilgariff (Glasgow, Scotland)
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