Garth,
Assumptions about steel frame weight are often wrong. A lot of the butted portions of a tube set get chopped off and mitered so the weight of a complete tube set when it comes out of the box and after it gets mitered is significant. There is also a lot of weight difference between the lightest and heaviest tubes. I weighed some 1" top tubes to illustrate this. A Columbus SP tube is 1mm/.7mm/1mm. It weighs 285 grams in its uncut 600mm length. A Reynolds 8/5/8 wall thickness tube (which is equivalent to the old common 21/24 gauge 531 top tube) weighs 210 grams (same 600 length) and the lightest one made in a 6/3/6 wall thickness weighs 160 grams.
My personal frame is made out of standard size (1" top tube) Tange Prestige with a wall thickness of 7/4/7. The frame without fork weighs 1550 grams. A frame make out of Columbus SP will weigh about 1000 grams more. I originally made it using a 6/3/6 down tube but I hit a pot hole and buckled it so I replaced it with a beefier version.
A set of 3 lugs weigh about 100 grams - the seat lug with a binder bolt weighs 50 grams. A set of 4 1010A Campy dropouts weigh about 200 grams. A bottom bracket shell weighs around 150 grams. The lightest fork crown I have weighs 100 grams. And the heaviest Cinelli style internal plugs weighs 160. Typically they are around 120 grams.
A 220 mm steerer weighs around 200 grams.
A custom framebuilder chooses the weight of the tubes based on trying to find the zone where a frame is flexible enough to be comfortable and yet solid enough so as not to sway around. It is not about the weight itself. This is often a lot lighter than production frames that have to assume the rider is heavy and built with brazing techniques need more margin for error. Jan Heine's love of his French bikes I speculate is in part due to those guys building with lighter tubes as much as the geometry of the frames.
Don't get me started on the assumption that tig welded frames are lighter than lugged ones (they are not unless the builder takes unusual steps).
Doug Fattic Niles, Michigan USA
From: Bianca Pratorius <biankita@comcast.net>
In looking at weight charts for complete sets of older upper level Columbus and Reynolds tubing sets for a mid size bike, I see weights ranging from just under two kilograms to just over. This would have made a theoretical total frame weight of about 4.5 pounds including the fork but not including the lugs and brake bridge and drop outs and chain stay bridge and solder. How much added weight could those lugs and four dropouts provide? I've held all those items in my hands (except for the fork crown and bottom bracket which do at least look substantial and heavy) and they seem rather light. Is it must be that those nine items plus the two bridges and solder weigh more than a pound. Was the selection of lugs, fork crown and bb for old bikes made somewhat on the basis of minimizing final weight or providing strength? I have been weighing stripped frames for years and have only seen one SLX in an average size that weighed in the low 5 lb range. The final weight for most upper stratus classic bike frame and fork seems to hover at five pounds 8 ounces to just over 6 lbs meaning that the parts other than the tubing set provided as much as 1/3 of the final heft. This makes the lug set a big part of a bike frame's heaviness. Now by going to a filet braze only two lugs would have been eliminated (the two at the headtube - all the rest would still be needed), and these lugs were the lightest anyway so that eliminating them would not have provided any real weight reduction providing of course that the filet braze isn't almost as heavy as the lugs in the first place. Also operating in the other direction to weight reduction is that heavy beefy looking dropouts made by campy seem to be preferred. That thick substantial look that they provided is, at least to me, a big selling feature. Also desired are things that add weight such as long long rear dropouts and a full complement of braze ons and a pump peg and those porky above the bottom bracket cable guides and a chain peg and front derailleur braze on. All of these extras provided the amenities that discriminating buyers wanted but they also added extra weight.
In light of the above (assuming I'm correct in my assumptions), it doesn't seem wise for a frame builder to have choosen the lightest tubing set just for weight reduction alone, because the difference between the lightest and the merely light tube sets in many cases is only three ounces or so. This difference could easily be made back up by eliminating an extra set of bottle boss braze ons or the front derailleur braze on or just selecting shorter or less ornate lugs for example. The future of steel used as a frame material should not be based on whether Reynolds can come up with increasingly lighter tubing sets (although the latest tubing set does claim to be quite a bit lighter). And finally, the lightest practical plastic and aluminum frames only seem to weigh two pounds less than the lightest steel (easily made back up by an extra water bottle, a GPS bike computer, a cell phone and all those silly CO2 cartridges people now carry with them.
Garth Libre in Miami Fl USA