CSI with partial fillet headtube aka bi-lamination

[nervexpro55]

I was wondering what years did Serotta build the CSI with the cool fillet brazed/lugged or bi-laminate headtubes. Anyone have some pics of theirs?
Thanks

[Mike748]

Since David has supplied the definitive answers, let me contribute some pictures.

http://i38.photobucket.com/albums/e109/Mike748/fillet2.jpg
http://i38.photobucket.com/albums/e109/Mike748/fillet1.jpg

[David Kirk]

The very first Colorados were all 1/2 lug because the tube shape and/or diameter wouldn't fit into lugs. Interestingly the down and seat tubes slipped over the sockets of the BB shell and were filleted on like that. The front end of the top tube was oval so a lug would not fit it either so the lug was modified so it was just a band around the head tube and then a point on top of the top tube.

Later we had lugs and BB shells made to fit the tubes and it cut down on labor in a huge way. Even later some of the tubes used were larger than existing lugs would allow so the 1/2 lug thing was brought out again.

It's interesting that this is, in retrospect, considered cool. We at the time knew it was not done for the cool factor but because that was the only way to make what we had on the shelves work with the new designs.

Only on rare occasions were the bikes made with the 1/2 lugs because they were custom. By far the vast majority of the 1/2 lug bikes were stock sizes. I recall that after we had lugs made to work with the tubes we would occasionally get requests for 1/2 lug bikes even though we could make them with the bespoke lugs. I seem to recall that we turned a good number of these down.

To me the 'bi-laminate' stuff we are seeing now is a bit funny. When I think that the only reason we did it back then was lack of money for proper lugs it makes me chuckle. I think that there are lots of reasons that folks did this b-lam thing in the past but I'll bet very few did it because it was thought to make a better bike or even that it looked cool but just for the simple reason that the builder was broke and had a bunch of stuff under his bench that didn't fit right so he modified them so they could be used. Art or pragmatism - you decide.

Dave

[palincss]

Art or pragmatism - you decide.
Dave

Both, I think. Fillet brazing was born of pragmatism and a lack of lugs, too. That doesn't make the results any the less beautiful; same for bi-laminate construction. "Necessity, who is the mother of invention."

[David Kirk]

Both, I think. Fillet brazing was born of pragmatism and a lack of lugs, too. That doesn't make the results any the less beautiful; same for bi-laminate construction. "Necessity, who is the mother of invention."

I agree it can be both.

But I disagree that fillets came about because of lack of lugs. Fillets predate lugs by a lot and lugs were developed to save labor as compared to fillets.

All the best,

Dave

[palincss]

I agree it can be both.

But I disagree that fillets came about because of lack of lugs. Fillets predate lugs by a lot and lugs were developed to save labor as compared to fillets.



OK, let me qualify that. The Taylors in a recent BQ interview mention that they got into fillet brazing (Siftbronze Welding, they called it) because lugs were in very short supply after WWII. My intro to fillet brazing was via Jack Taylor bicycles, and I assumed that their experience was general.

[nervexpro55]

The very first Colorados were all 1/2 lug because the tube shape and/or diameter wouldn't fit into lugs. Interestingly the down and seat tubes slipped over the sockets of the BB shell and were filleted on like that. The front end of the top tube was oval so a lug would not fit it either so the lug was modified so it was just a band around the head tube and then a point on top of the top tube.

Later we had lugs and BB shells made to fit the tubes and it cut down on labor in a huge way. Even later some of the tubes used were larger than existing lugs would allow so the 1/2 lug thing was brought out again.

It's interesting that this is, in retrospect, considered cool. We at the time knew it was not done for the cool factor but because that was the only way to make what we had on the shelves work with the new designs.

Only on rare occasions were the bikes made with the 1/2 lugs because they were custom. By far the vast majority of the 1/2 lug bikes were stock sizes. I recall that after we had lugs made to work with the tubes we would occasionally get requests for 1/2 lug bikes even though we could make them with the bespoke lugs. I seem to recall that we turned a good number of these down.

To me the 'bi-laminate' stuff we are seeing now is a bit funny. When I think that the only reason we did it back then was lack of money for proper lugs it makes me chuckle. I think that there are lots of reasons that folks did this b-lam thing in the past but I'll bet very few did it because it was thought to make a better bike or even that it looked cool but just for the simple reason that the builder was broke and had a bunch of stuff under his bench that didn't fit right so he modified them so they could be used. Art or pragmatism - you decide.

Dave
Dave
Was most of the bi-lam's made for 1.125 fork's? I remember a dealer telling me they did that construction for the oversize forks or for more stiffness in the front end.

[David Kirk]

Dave
Was most of the bi-lam's made for 1.125 fork's? I remember a dealer telling me they did that construction for the oversize forks or for more stiffness in the front end.

Nope... Most of the 1/2 fillet stuff predated OS forks by a good bit. Most of it was do to OS top and down tubes and not head tubes.

Dave

[Dekonick]

Now that you mention it, even my not top of the line Colorado CR was made this way. Mind you - I mean Colorado concept tubes with lugs all around.

[David Kirk]

OK, let me qualify that. The Taylors in a recent BQ interview mention that they got into fillet brazing (Siftbronze Welding, they called it) because lugs were in very short supply after WWII. My intro to fillet brazing was via Jack Taylor bicycles, and I assumed that their experience was general.

Some of the earliest steel bikes wee fillets and that goes back a good 50 years before the Taylors. The advent of lugs helped the explosion of bikes in the early 1900's.

Don't get me wrong. I like the 1/2 fillet bikes very much. I've built many hundreds of them and they are fun to do. I just can't get over the irony that what we as builders at the time saw as a cheap way to get the job done is now being revered in a higher sense as art.

I've thought of building some bikes in a limited run like the old Colorados just for the fun of it as they were fun to build.

We'll see.

dave

[palincss]

I've thought of building some bikes in a limited run like the old Colorados just for the fun of it as they were fun to build.


Fun to build is a good reason in and of itself. Plus, people like them.

[Dekonick]

Dave, your fillets are so well done they meld into the tubes. They make the bike seem a seamless piece of machinery.

[David Kirk]

Fun to build is a good reason in and of itself. Plus, people like them.

Two very good reasons.

dave

[Ahneida Ride]

Dave, your fillets are so well done they meld into the tubes. They make the bike seem a seamless piece of machinery.

When it come to quality craftsmanship, Mr. Kirk sets the reference
standard, and that straight from the grapevine and rumor mill were
people tend to say what they really think.

yea, he is that good.

[nervexpro55]

Mike748
Thanks for posting pics of the bi-lam bike. COOL.