Originally Posted by cyccommute

The bonded frames usually consisted of a tube over a socket...look at the Raleigh Technium frame as the prime example...that was bonded in place. Steel lugs are tubes placed in the socket and brazed into place. If you fit an aluminum tube into the lug like a traditional steel frame, the lug would have to be huge to be strong enough. A steel lug has a wall that is about 1/8" thick. Aluminum, with a third of the strength of steel would have to be proportionally thicker leading to walls that are 3/8" to 1/4" thick. Even I would have to admitt that the lugs would be ugly...and I like the look of aluminum tubes. Even the glued aluminum frame lugs were less than pretty.

I also agree with LesterofPuppets. I don't recall ever seeing a glued aluminum Schwinn.