Hi,

How flexible are lugs?

We use LongShen lugs for oval tubes for instance (LT208-79). This one is for a toptube of 36.5x27.4 and is 79 degrees.
My old framebuilder used this lug to build our frames even if the angle was 85 degrees on certain framesizes. And we never had problems in the past 10 years. (I also wasn't aware of this angle mismatch)
My new framebuilder refuses to change the angle more than 1.5 degrees. So we need to change the geometrie of the frames.

So what is a safe tolerance on the angles?

Marco

Stamped & bulge formed lugs, brass brazed, are way more flexible than investment cast lugs for silver brazing..

marcow- Are you a bike factory? What kind of bikes are you making with an 85* angle?


FB is correct in that older stamped, bulge formed lugs have a far greater ability to be manipulated then cast ones do. A couple of degrees is about the most a cast lug can be forced into before serious and surgical methods are employed. Andy


If your production is large enough you could consider having a spec run of lugs produced.

he has said before that he contracts builders to make frames for his company.

I would be somewhat reluctant to make someone go past the point where they feel comfortable on this issue. After about 1.5 degrees, the lugs should be re-formed so that there aren't stresses built into the frame.

Modern and currently made bulge formed lugs are still out there. Bicycle frame components


I still wonder about the 85* frame tube angle being done with a lug. I can think of reasons to have such a steep angle but they are all way out there (circus bikes, cargo bikes). Andy

sloping top tube. The Llewellyn sloping top tube lugs are 78 degrees. 85 would be more sloped. I think changing the design to meet the needs of the vendor is probably a good idea, it can't be much of a change.

Does anyone know of a supplier who sells these lugs? Pretty nice looking. I like working with the pressed lugs too as they are so easy to manipulate.

Doug Fattic sells the blank ones, I think.

That's right, I have in stock Nikko bulge formed blank lugs in standard (for 1" top tubes) and oversize (for 1 1/8" top tubes) sizes. They fit 1 1/4" head tubes for 1" steerers. In addition I have their spearpoint model for standard size tubes. These were a kind of copy of the old stamped and welded Cinelli lugs (before they started marketing investment cast lugs). I liked them because the spearpoints had enough room for a window or some other kind of design. I often put the customer's initial in the down tube lug. These lugs are much easier to alter their angles than IC lugs. The sale of these lugs is a fundraiser for our Ukraine Bicycle Project.

Included with the blank lugs are instructions on how to create the design on twice life size templates with a grid pattern, how to put these designs on the lugs and how to cut them out. Many of my frame building class students choose to learn how to do this.

email me for more information. Use my name in lower case without spacing and after the at put a q (as in quality) a t and a m and finish with a net.