bilaminate lugs of sorts

[Mike Mcdermid]

I need some background info on bilaminate lugs

As I understand it the old school way is to make them from sheet but can be made from two pieces of tube?

would this be correct

[e-RICHIE]

I need some background info on bilaminate lugs

As I understand it the old school way is to make them from sheet but can be made from two pieces of tube?

would this be correct

Yes - the term bilaminate refers to the visual affect not the method used to achieve it.
I'm sure its origins lie in workshops where the processes of the day were limited to 1) lugs
or, 2) no lugs (brass mountains). A way to achieve unusual or unconventional frame designs
using the only two known joining methods resulted in combining them to create a hybrid.

[Mike Mcdermid]

Hi eRICHIE

I'm reading into your reply that this is purely a visual technique to achieve a faux lug look, not actually a way of fabricating a lug structurally?

[Too Tall]

Hi eRICHIE

I'm reading into your reply that this is purely a visual technique to achieve a faux lug look, not actually a way of fabricating a lug structurally?

Maybe T.K. can chime in. IIRC I've seen quite a few practical uses in his shop. From my untrained eye's perspective you are generally right about this. None the less, Jeff makes lugs and there are some odd bikes where this is required not "desired" ;)

Also: http://townsendcycles.blogspot.com/

Also: http://www.winterbicycles.com

Signature bilaminate- Bilaminate bicycles are made with a hand cut seat tube sleeve and hallmark head tube lug. This distinctive build style offers superior strength and full design freedom. The bilaminate platform also allows for carved visual and aesthetic personalization.

[Jonathan]

Chuckle.....brass mountains

[Eric Estlund]

That line in TT's post is from my site, so I might as well elucidate.

Bilaminate is a term that seems to mean different things to different people.

In the older British (Hetchins, etc) sense it was adding a cosmetic stamped plate to an existing lug- basically "laminating" on a visual element.

When I use the term I am referring to a joint that is fillet brazed on one end and sweat-via-lug-socket on the other. For my uses this is generally how I refer to my seat tubes and head tube "mono-lug".
4982847189_be339befd8.jpg

If you are taking two tubes and making a free-standing lug I would argue that you are making a fillet brazed lug, not a laminate. I don't want to speak for Spetrum, but that is how I see their in-house lugs.I do this when I need a lug in a non-conventional set up. The lug needs to be structurally sound on it's own, and the lugged construction under it needs to be solid lugged construction.
6259400888_d9f77f95b4.jpg

In some ways these are semantic distinctions, but I think they go to what one is trying to achieve. Figure out why you want to do what you are trying to do, then work backwards to figure out the structurally sound approach to get there.

3219912096_0a9143bd77.jpg

I hope that helps.

[e-RICHIE]

Hi eRICHIE

I'm reading into your reply that this is purely a visual technique to achieve a faux lug look, not actually a way of fabricating a lug structurally?

Yes - but it's not a lug. It's a lug-looking joint. And its roots are in an era in which lug designs (geometries)
were not made for every possible variation or diameter. So rather than make the frame lugless, the faux part
was added as a paean to an already accepted aesthetic.

[Eric Estlund]

This is clipped from hetchins.org:

mo2-st-01a.gif

"The arrow shows the place where the stamped extension was brazed to the original casting. The seam was filed smooth to be invisible. "

This adding of a visual elements what I think of as classic British bi-lam (attached to the tube and the lug), and is not what I'm referring to with my own work when I use the term.

[Dancingbear]

Yes - but it's not a lug. It's a lug-looking joint. And its roots are in an era in which lug designs (geometries)
were not made for every possible variation or diameter. So rather than make the frame lugless, the faux part
was added as a paean to an already accepted aesthetic.

Whoa. I hadda look that up, and I have one of those liberal arts degrees.........

[e-RICHIE]

Whoa. I hadda look that up, and I have one of those liberal arts degrees.........

This method was born out of trying to be the same, not different. In the eras that these were (more) popular, having bicycles that adhered to an aesthetic convention would have been more accepted than ones that didn't. That folks are doing it again when there is no accepted convention for what we do (top tubes are not horizontal, tube diameters are not standardized - or even round, graphics are placed asymmetrically, etc) makes me curious about why some of these methods are being employed. To my mind, it's like discovering your folk's favorite records, finding an artist you like that maybe your peers haven't heard of, and then trying to play the tunes in real time as a way of being ahead of the curve - and also playing the improvisations that were part of the original. Think about it. This is 2012 not 1951. If you were doing this then, and are still making frames, I can understand it because you are essentially taking your DNA and bringing it into the present. But since other methods and techniques have superseded it, why go into the vault. They (those from the DeGaulle era) did it because they didn't have what we have.

When these chats come up (and I realize I am encouraging the discussion) I often think of the transmission/tradition text that lives here. It's something I am passionately interested in. And my points of view are not meant to call anyone out, and I am not asking anyone to defend themselves, but only to have the conversation at all.