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6/4 vs 3/2.5 Ti- Is there really that big a difference?(21 posts)

6/4 vs 3/2.5 Ti- Is there really that big a difference?MXL02
Oct 9, 2003 5:03 AM
If so how come Seven and other high end frame builders don't go to 6/4, especially now that Reynolds has the seamless tubeset?
re: 6/4 vs 3/2.5 Ti- Is there really that big a difference?Greg B
Oct 9, 2003 6:07 AM
According to Reynolds, the 6/4 is approx. 23.5% stronger than 3/2.5 and 28.6% stiffer than 3/2.5. So you decide.

and one heck of a lot more expensive...weiwentg
Oct 9, 2003 6:27 AM
btw, Mark, how is the MXL doing? I can't remember if you still have it.
Still have it and love it,MXL02
Oct 9, 2003 8:37 AM
but I'm considering getting a Ti frame, to try something different, and also so I can travel with it. I get finicky about trying to pack that expensive paint job on the 'nago...the Master X-light is a great all round frame, but it is a little flexy when trying to really hammer. I am looking at getting a custom Seven or Serotta and having them make it really stiff, to have something more race-like than the MXL.
MXL Flexy? Then don't get TI...ColnagoFE
Oct 9, 2003 10:17 AM
No way is my MXL flexy. My Merlin Extralight was flexy. Don't even think about getting TI if you think your MXL is already too flexy. It's pretty stiff compared to anything I've ridden before. You're right about the geometry though. They are designed more for long stage races so they don't have a crit geometry. Good for all day riding--not as much for fast twisty crits maybe. BTW...Serotta make a pretty stiff TI bike, but it will weigh as much as your MXL by the time you get it the way you want it.
Exactly why I asked the question...MXL02
Oct 9, 2003 8:40 AM
I know what Reynolds claims...does anyone really believe it makes that much difference? Especially considering all the other tube variability options that frame builders use to build in certain ride characteristics...such as butting, cold working, etc?
one word: Ovalmaster. :)weiwentg
Oct 9, 2003 8:44 AM
I'm actually getting a Dream Plus, myself, btw.
re: 6/4 vs 3/2.5 Ti- Is there really that big a difference?geeker
Oct 9, 2003 7:58 AM

"3Al/2.5V Habanero frames are built from 3Al/2.5V titanium alloy, or titanium alloyed with 3% Aluminum and 2.5% Vanadium. This is an ideal material to build a frame from, since it has an incredible strength to weight ratio, but is still resilient enough to withstand considerable flex without permanent damage. This is the material almost all of the highest quality titanium bike frames are made from, and is a mainstay in the aerospace industry because of its impressive properties.
6Al/4V This alloy (as you'd probably guess by now) is comprised of titanium alloyed with 6% aluminum and 4% Vanadium. There are a lot of claims made about the strength of 6/4, but most of it is based on "textbook" numbers for sheet stock, not tubing. All 6/4 bike frames are made from seamed tubing, that is, flat sheets which have been rolled into a tube and welded. The problem is that the weld reduces the strength and resilience of the tube. In addition, 6/4 can only take about half the elongation that 3/2.5 can before it's permanently damaged. In the final analysis, you end up with a bike that's at best just a little stronger, but maybe less able to absorb punishment - plus it'll be a LOT more expensive. We think it makes more sense to save the weight elsewhere in the bike, where it won't cost so much per gram. "
Wrong...Reynolds now makes SEEMLESS 6/4 ti tube sets (nm)Greg B
Oct 9, 2003 8:01 AM
I think this is old information--seamless 6/4 is available now-nColnagoFE
Oct 9, 2003 8:01 AM
Sorry, didn't know. Stand corrected (nm)geeker
Oct 9, 2003 8:28 AM
From What I have Heard....Spiderman
Oct 9, 2003 8:49 AM
I know this sounds like hearsay but for a while, there was no tubing (now there is) and the 6/4 is/was very hard to work with.

I think the "strength" numbers are more based on the strength of the density of the material or compression (these aren't technical terms, just how i picture it in my mind). The 6/4 doesn't have a stronger tensile strength (how far you can bend it without causing permanent, non-reversable structural damage) than the 3/2.5 tensile strength.

I know a few manufacturers use it on their dropouts where it is a better use of 6/4's properties.
re: 6/4 vs 3/2.5 Ti - Seven Cycles' opinionAnonymous Gerbil
Oct 9, 2003 9:04 AM
Taken straight from their web site -

6-4 Titanium: Better or Just More Expensive?

5 Febuary, 2003

6-4 has reemerged as the latest buzzword in frame materials. The marketing promises lighter, stronger, and stiffer bikes. But what's the reality, and is the significant additional cost of 6-4 providing any benefit?

What is 6-4?
Alloyed from 6% aluminum, 4% vanadium, and 90% titanium, 6-4 offers some very favorable raw material properties, which is why we use 6-4 plate to fabricate dropouts for our frames. One of the properties that makes 6-4 an optimal material for dropouts is its toughness. But this toughness also makes it unattractive as a material from which to make tubing. Applying the techniques used to draw 3-2.5 tubing—the most common titanium alloy used in bicycle frame construction—to 6-4 costs more and wears tooling quickly. In addition, tube wall consistency, concentricity, and finish quality are limited. At this time, no U.S. mill offers seamless 6-4 tubing, though some offer seamed, or welded, 6-4 tubes.

The Problems with Seamed Tubing
The earliest "6-4 bikes", along with many current ones, used seamed tubing in one or two frame tubes, while the remaining tubes were 3-2.5. Two issues prevent us from favoring this method of tube manufacture. First, seamed tubing is fabricated by rolling 6-4 sheet into a tube shape while simultaneously welding the seam that is created. The result is a tube that has a welded seam-a potential failure point-along its length. This seam acts as both a hard point and a stress riser since the weld bead is thicker than the tube itself, and the weld creates an inconsistency in the tube.

Second, 6-4 sheet is designed to be used as a sheet, not as a tube. Once rolled into a tube, its grain orientation can lead to premature tube failure. Independent fatigue tests show that tubing made from 6-4 sheet does not have the fatigue life of a properly drawn 3-2.5 tube.

What About the New Seamless 6-4 Offerings?
It's true, seamless 6-4 tubing is now being marketed to the bike industry. Unfortunately, however, these offerings are just a couple of tubes of predetermined length, diameter, and wall thickness.

Most high-end bike builders understand the benefit of using specific tube sets for each of the different size frames in their lineup. This is known as "size-specific" tubing, which is a term coined by Seven's Rob Vandermark when he was developing this design concept back in his days at Merlin. The theory is that the rider of, say, a 49 cm road bike would desire completely different ride characteristics than the rider of a 59 cm, whom one would expect to be heavier or more powerful. We take this concept even further by offering "rider-specific" tube sets, understanding that even two riders on the same size bike often have dramatically different requirements and preferences for ride characteristics.

Size-specific and, in particular, rider-specific tube sets require a wide array of tube sizes (diameter and wall thickness). Seven draws on about 30 different straight-gauge sizes and a virtually infinite number of butted tube sizes to ensure the optimal ride characteristics, durability, and weight-to-performance of every Seven frame. So the extremely limited 6-4 tube sizes available are inadequate for high-end frame building.

One might argue that the strategic use of 6-4 tubes in combination with 3-2.5 tubes would create a better bike. But compare the weight of a 6-4 bike to the lightest 3-2.5 offerings, like our Alta; there is no weight advantage. And there is no stiffness or strength benefit either, since 6-4's stiffness is offset by its density, and the butting techniques employed in the 6-4 tubes currently available have a negative impact on fatigue strength. So 6-4 only adds expense.

Tough to Beat 3-2.5
Historically, aerospace and defense Industries have driven mate
re: 6/4 vs 3/2.5 Ti - Seven Cycles' opinionAnonymous Gerbil
Oct 9, 2003 9:18 AM
Oops- looks like my message was cut off - guess I hit the max word limit. But you get the idea.
re: 6/4 vs 3/2.5 Ti- Is there really that big a difference?NP
Oct 9, 2003 9:17 AM
I should make a disclaimer - I have never really understood about the frame "stiffness" that many people talk about. Rather, I think a frame is either properly put together with the right tubes for the right size of frame (or rider, if it custom) or it isn't. But, that out the way, let's answer your question. Is there really a big difference? No. I have a Merlin Cyrene (3/2.5 ti) and a custom Strong 6/4 ti (which is the most recent custom frame on the Strong website if you want to look). Both are brilliant. Both do exactly what they are supposed to do. Do I notice any difference in ride from the tubing? No. Do I notice a difference in the ride from the design? Yes, but that's because the frames were not built with the same specs because they were not built for the same purpose - the Cyrene has Campy 10 and goes places quickly; the Strong is lighter but slower but then it should be because it's a fixed/ss commuter/tourer. So, why (I hear you all shouting) did I pay for a more expensive 6/4 ti frame? Well, because I wanted one, I could afford it and you only live once. I'm not a great one for buying every new-fangled thing, but the 6/4 ti appealed to me. It still does. Better spend it on a frame that will last years than the newest thing in wheels which will be history next season.
Thanks...nicely done.MXL02
Oct 9, 2003 9:49 AM
Appreciate you input. Your assessment plus the info from the Seven site pretty much answers my questions. BTW- I think having a Custom 6/4Ti fixte is awesome! How 'bout a photo...?

PSS- I don't know the last time you rode a steel bike, but if you were to ride one now, especially climbing, my guess is you would tell a difference in stiffness between the Merlin and the Steel.
A bit embarrassing....NP
Oct 9, 2003 10:55 AM
...but I do have a steel bike - a Pegoretti Marcelo. This is much more of a racer's (sprinter's indeed) bike (with its fat tubes and big chainstays) than either of the ti bikes. But then the geometry (chosen by Dario Pegoretti) is quite radically different to those bikes. So it rides differently, with more snap and acceleration. Is that the tubes? Maybe... More the design, I think.
No need to be embarassed....lyleseven
Oct 9, 2003 2:17 PM
Couldn't agree more about the way you spent the money. If we have to have vices, I am so grateful mine is spending money on select bikes. Please share any feedback if you get a moment on the Pegoretti, such as comfort, climbing, descents, etc.
Pegoretti MarceloNP
Oct 10, 2003 9:05 AM
Way off topic now, so apologies to those who are not interested.

Start at the start. The Marcelo is quite radically different in geometry than either of the ti bikes - the Marcelo has 52st and 57tt (chosen by Dario Pegoretti after much measuring and discussion) whilst the ti bikes are basically 55 square. So, at the front end I have quite a different position and at the back end (although saddle height, seat layback and KOPS (if you believe in that) are the same on all three bikes) there is more compression/flexion of the hips. I don't mind this difference, in fact it's what makes owning different frames built by different people interesting - more than one way to skin a cat, particularly if it is a different type of cat.
So the Marcelo is much more of a racing frame in its basic design and much more of a racing frame in its specific building for me. The result, unsurprisingly, is that it feels much more snappy and accelerative than the ti bikes. Is that the materials or the geometry (or both)? Can't say.
What I can say is that the Marcelo climbs with a real degree of spring. I am no climber and never will be - 95kg and could maybe (with a Lance type starvation diet) shed 3-4kgs. So I need all the help I can get on big Continental climbs (such as a Campy 13-29 rear cassette). But the Marcelo frame seems to spring you from one side to another as you spin/grind up the hill. Maybe it's all in the mind but I don't think so.
On the way down, it's point and go. Sure, stable, goes through rough asphalt, inspires confidence. Do I take my hands off the bars and peel a banana? No, but then I am too much of a coward to ever do that - my wife (and kids) would kill me if I didn't kill myself.
On the flats it just goes. I can't tell you if it's a quick on the uptake as an aluminium frame because I've never had an al frame. But if the marcelo was any quicker my legs wouldn't keep up with it.
Yet, you can do long hours in the saddle without feeling like a punchbag. I am not a sad old "steel is real", "steel is buttery" freak but it's a nice ride for the day.
If I had to chose only one, well this would be it (I think....)
Thanks for the feedbacklyleseven
Oct 10, 2003 6:52 PM
I'm going to check them out overseas next year on my tour.
re: 6/4 vs 3/2.5 Ti - Seven Cycles' opinionAnonymous Gerbil
Oct 9, 2003 9:20 AM
Taken straight from their web site -

EDIT - Removed because of copyright issues. Click on link.