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straight-gauge vs butted, advice?(8 posts)

straight-gauge vs butted, advice?weiwentg
Jan 23, 2004 9:18 PM
I'm considering a custom ti frame. I want something stiff enough to race on and crashworthy (although I don't intend to lay it down if possible), but still light. I am 120lbs, 5'5". straight gauge would save money. I'm going with Seven, and I would like to get the Alaris with an aero downtube (no snide remarks, please). Axiom with an aero downtube would be too expensive. advice, anyone?
I'll try to not be <b>dogmatic</b>, but...Dave_Stohler
Jan 23, 2004 9:29 PM
Although the non-butted spokes are stronger in absolute terms, a wheel made with DB spokes will be more durable.

Why, you may ask? Because the thinner center section will elongate more than the thicker straight-pull spokes will. This reduces the cyclical stresses at the hub end, making the spoke much more resistant to fatigue.

To make a long story short-using DB spokes will pay off in the long run.
Man, it's been a <b>long</b> night!Dave_Stohler
Jan 23, 2004 9:38 PM
OK, I guess the question was about butted tubes, correct? OK, it depends on what you can afford, and how light you are. DB tubes will be a bit lighter, and a bit less able to withstand abuse. If you don't mind a bit of extra weight, save a few buxx by going for straight-guage tubing. Maybe it won't ride as smooth, who knows...
my bad, should have said FRAME tubesweiwentg
Jan 24, 2004 7:10 AM
ah well. thing is, while I am very light, I can put out a fair amount of power in a sprint. and I technically could afford an Axiom. the problem is, I want an aero downtube (aero weenie), which adds $500. I've got a pretty large insurance settlement coming from the guy who trashed my frame (and broke a few bones), but that'll take a while.
Aero down tube = Stiff ride & Flexy bottom bracketNessism
Jan 24, 2004 9:39 PM
The loads in a down tube are a combination of torsional and bending (about 60/40 in favor of torsional). As one might imagine, ovalizing a tube increases the bending stiffness in one direction while reducing it in another, and to a lesser degree, reducing torsional stiffness as well. Bottom line is that aero down tubes make the ride stiff because the oval resists vertical flexing, while also reducing bottom bracket lateral stiffness. Not a good design in my opinion considering the aero significance is only very slight.

I ride a TST built straight gage Ti frame using 1-1/4" top and seat tubes, 1-1/2" down tube, 1" head tube, and 7/8" tapered chain stays. I weigh 165 lbs and find the ride to be fairly stiff (which is the way I like it). My old Ti frame, Eddy Merckx EX with straight gage tubing, had a 1-3/8" down tube and the ride quality was more comfortable but the bottom bracket area of the frame moved more than the TST frame. Considering your weight, a 1-3/8" down tube frame would be just fine. Butted tubes are another way to adjust ride quality but not the only way.

In summary, a straight gage frame is fine as long as the tubes are sized properly, and stay away from aero down tubes.

My opinion as always. Others may vary.

Good luck.

Ed
re: straight-gauge vs butted, advice?lyleseven
Jan 23, 2004 9:47 PM
Of course you were talking about tubes. Butted is lighter and may have other advantages. Seven is fantastic whether Axiom or Alaris. I have Ti and steel Axioms and if you go Alaris to save the money, you will love the new Seven carbon fork. It makes my steel Seven as smooth as butter. At your weight the Alaris should be fine if matched with a good fork. Good luck!
Butted tubeing for me.Spoke Wrench
Jan 24, 2004 10:45 AM
My OPINION is that butted tubeing is what gives higher quality bikes that indescribeable ride quality. Personally, I would much rather sacrifice the aero down tube for butted tubeing. I'm sure other people may have differing ideas.
The wrench has it absolutely rightKerry Irons
Jan 24, 2004 6:41 PM
Back in the day, we faced the same choices in steel tubing. There was no question - straight gauge was cheaper and butted tubes made a much better frame. The same is true for any frame material today.