a bit curious about the joinery on this ebay Serotta

[eddief]

http://www.ebay.com/itm/58-x-60-Sero...item35de3eb7fa

From the photos it looks as if the tubes are joined as sort of half lugs / half fillets. Am I seeing things? Don't think I've ever seen one like it.

Bottom bracket and top of headtube look unusual to me.

[rwsaunders]

Bi-laminate frame construction. I've seen it in the past on a few Serottas, most recently on a CSI.

http://flickrhivemind.net/Tags/bilaminate/Interesting

[eddief]

all one or all the other, and not bi. and that ebay example looks a bit sloppy to me. no biggy, was just curious.

[jbrainin]

Colorado II's were all made this way. Dave Kirk can explain why.

[happycampyer]

Dave Wages does the bi-lam thing from time to time, and I wouldn't kick one of those out of my garage... they're exquisite.

[vav]

This bike was in display at the builder's ball in Providence. Drool worthy for sure.

http://www.chapmancycles.com/2014/05...ate-road-bike/

[David Kirk]

The reasons for putting the bike together this way were 100% pragmatic. Ben wanted to use the then huge down and seat tubes (1 3/8" as opposed to the then standard of 1 1/8") and there were no bottom brackets made to fit the larger tubes...........and there wasn't enough money in hand to have new BB shells made so instead of putting the seat and down tubes into the sockets of the BB shell we put them over the sockets (of you look inside one you can see the points and windows of the unused sockets) and fillet brazed them in place. It worked exceptionally well.

The top tube was a similar story - a larger top tube was used and lugs could not be had in a size to work with the tube so in this case the sockets were cut off. In the rear the remainder of the seat lug acted as a seat tube reinforcement and seatpost binder and in the front the lug was cut back that that it was really just a reinforcing ring around the upper end of the head tube. Both ends were filleted and it worked very well and looked pretty cool.

Back then I never heard the term 'bi-lam'..............it may have been out there but we never used it at Serotta. We also didn't go out of our way to build bikes in this way for the fashion of it. It was a simple and pragmatic way to hook the tubes together and have it look nice while using stuff that was in the stock room. We didn't set out to make cool joints for the sake it it..........we wanted to get the bikes built, have them stay together, and still look like Serottas so that we could pay the bills and get our paychecks.

Cool stuff.

dave

[rwsaunders]

Originally Posted by david kirk

the reasons for putting the bike together this way were 100% pragmatic. Ben wanted to use the then huge down and seat tubes (1 3/8" as opposed to the then standard of 1 1/8") and there were no bottom brackets made to fit the larger tubes...........and there wasn't enough money in hand to have new bb shells made so instead of putting the seat and down tubes into the sockets of the bb shell we put them over the sockets (of you look inside one you can see the points and windows of the unused sockets) and fillet brazed them in place. It worked exceptionally well.

The top tube was a similar story - a larger top tube was used and lugs could not be had in a size to work with the tube so in this case the sockets were cut off. In the rear the remainder of the seat lug acted as a seat tube reinforcement and seatpost binder and in the front the lug was cut back that that it was really just a reinforcing ring around the upper end of the head tube. Both ends were filleted and it worked very well and looked pretty cool.

Back then i never heard the term 'bi-lam'..............it may have been out there but we never used it at serotta. We also didn't go out of our way to build bikes in this way for the fashion of it. It was a simple and pragmatic way to hook the tubes together and have it look nice while using stuff that was in the stock room. We didn't set out to make cool joints for the sake it it..........we wanted to get the bikes built, have them stay together, and still look like serottas so that we could pay the bills and get our paychecks.

Cool stuff.

Dave

+1.

[eddief]

DK has just explained why. Thanks.

Seems as if some artisans have indeed turned it into an art.