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Engineering rationale behind lugs shape?(8 posts)

Engineering rationale behind lugs shape?Bruno S
Mar 19, 2003 1:11 PM
The post below made me wonder is the contoured shape of lugs has an engineering reason behind it or are they like that for aesthetics only?

Is the brazed joint between the lug and the tube stronger at the edges? If so having such contoured forms and holes in the lugs would make sense since it would increase the length of the edges.
These must be super strong!Spunout
Mar 19, 2003 1:15 PM
Probably totally aesthetic. Cutouts help braze the solder deeper into the lug. Points are like any load bearing joint, little farther away from the joint and thicker at the joint itself. Take a lug, cut one side and roll it flat and you're looking at a suspension bridge.
now that's true art nmgreg n
Mar 19, 2003 2:37 PM
Is it made in china? nmQubeley
Mar 19, 2003 2:59 PM
It's is a Columbinemhinman
Mar 19, 2003 5:30 PM
It's is a Columbinemhinman
Mar 19, 2003 5:31 PM
sorry here is the link
re: Engineering rationale behind lugs shape?rufus
Mar 19, 2003 4:11 PM
the underside of the lug,usually at the downtube/headtube junction, and the seattube/toptube, will usually be rounded a bit. otherwise, too sharp a point, and it can work like a can opener on the tube.
Grant Petersen has written a lot about this...cory
Mar 19, 2003 5:50 PM
I didn't pay much attention, because it's not that interesting to me, but Grant at Rivendell ( did a lot on this when he was choosing lugs for his bikes. I don't think it's on the website, but you can order back copies of the Reader. There's much more to it than I realized. Worth reading his stuff--he even shows some pictures of old-fashioned lugs and explains where they're good or bad.