# 3Al/2.5V vs 6Al/4V



## lawrence (May 17, 2005)

What is the difference between 3Al/2.5V and 6Al/4V regarding handling, stiffness, vibration absorption, strength, one is better than the other? I was told the 6A/4V is stronger so wouldn't that be better? I know what the #'s and Al/V mean, I just don't know if one is perferred over the other, especially if I have a choice.


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## mayukawa (Mar 14, 2006)

Ideally, you would want to use both types on a bicycle to optimize the frame design.


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## Kerry Irons (Feb 25, 2002)

*Strength*



lawrence said:


> What is the difference between 3Al/2.5V and 6Al/4V regarding handling, stiffness, vibration absorption, strength, one is better than the other? I was told the 6A/4V is stronger so wouldn't that be better? I know what the #'s and Al/V mean, I just don't know if one is perferred over the other, especially if I have a choice.


6/4 is stronger than 3/2.5 thereby allowing the builder to make a frame that performs the same but weighs less (thinner walled tubing). Handling, stiffness, vibration absorbing, are all about frame design (and wheels/tires) and not very much about materials. Few makers use 6/4 because it is both expensive and hard to work with. If you have a choice, the 6/4 frame will cost more and be lighter, but otherwise could be designed to ride very similarly to a 3/2.5 frame.


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## tigoat (Jun 6, 2006)

*titanium frames*



lawrence said:


> What is the difference between 3Al/2.5V and 6Al/4V regarding handling, stiffness, vibration absorption, strength, one is better than the other? I was told the 6A/4V is stronger so wouldn't that be better? I know what the #'s and Al/V mean, I just don't know if one is perferred over the other, especially if I have a choice.


Well, correct me if I am wrong but I thought that most 6/4 ti frames are not completely made out of 6/4 so I cannot see what the big fuss about them. We can argue from here to eternity in regards to which grade of titanium gives a better performance but it all boils down to how much more are you willing to spend to have a couple of 6/4 tubing on your frame to save about .25 lb. Saving a lousy .25 lb on a bike as a whole with a 25% premium for a 6/4 frame does not make a whole lot of sense to me. I have ridden a Litespeed Ultimate (a 6/4 frame?) and a Vamoots side by side and I was not able find any magical difference between the two frames. Have fun!


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## Mark McM (Jun 18, 2005)

*Diamond is the word's hardest substance - but you can't build a bike from it*



lawrence said:


> What is the difference between 3Al/2.5V and 6Al/4V regarding handling, stiffness, vibration absorption, strength, one is better than the other? I was told the 6A/4V is stronger so wouldn't that be better? I know what the #'s and Al/V mean, I just don't know if one is perferred over the other, especially if I have a choice.


In similar tempers, 6Al/4V is harder and stronger than 3Al/2.5V - but that doesn't mean that it will always build into a better frame. After all, a diamond is the world's hardest substance, but that doesn't mean it would make a very good frame.

While 6Al/4V is stronger (and a little bit stiffer) than 3Al/2.5V, it is also more brittle and less ductile. That makes it more difficult to form into different shapes - including the simple round tubes that most frames are made from. Most 3Al/2.5V tubes used in bike frames are seamless (meaning they were formed into a continuous round tube), whereas most 6Al/4V tubes are seamed (meaning that they started as a sheet of metal and were curved into a round shape, and then welded to form a continuous tube). Usually, a seamless tube will have more uniform properties than a seamed tube.

Because it is more brittle, it is also more difficult to form 6Al/4V tubes into different shapes, such as ovalizing or tapering, so it is more difficult to form the shapes that are more optimized for bicycle frame design.

Cold working can increase the strength of both 6Al/4V and 3Al/2.5V. However, because it is more brittle, it is frequently necessary to anneal 6Al/4V (sometimes several times) to a softer condition during the forming of frame tubes. So in the final frame, there may not be much difference in the actual strength of 6Al/4V and 3Al/2.5V tubes. So, while it may be theoretically possible to build a 6Al/4V frame that is substantially stronger than a 3Al/2.5V, in practice these strength improvements generally aren't fully realized.



Kerry Irons said:


> 6/4 is stronger than 3/2.5 thereby allowing the builder to make a frame that performs the same but weighs less (thinner walled tubing).


I don't believe this is always the case. Frequently, 3/2.5 frames are lighter than 6/4 frames. Take for exampl the Litespeed Ghisallo, which is the lightest frame Litespeed makes. According to the 2006 web page, the Ghisallo is a mix of 6/4 and 3/2.5, while the Vortex is all 6/4 - and yet the Ghisallo is lighter. I'm pretty certain the 2005 and earlier Ghisallos were all 3/2.5 (although Litespeed probably couldn't admit that because then they would have to explain why it was both more expensive and lighter than their 6/4 frames).

But of course, in the end, what is more important than what metal a frame manufacturer uses is how they use it.


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## Phat&SlowVelo (Nov 27, 2004)

*ok so I'll chime in.*

I have both, 6/4 and a couple of 3/2.5's one of each buy Moots. 
we know the numbers, so I'll give you a ride report, the 6/4 is a stiffer bike, has a little bit of that alum feel, but not harsh, it's lighter than my 3/2.5 bikes but isn't quite as nice in the ride department. Of the two, I prefer the 6/4, why? Cuz, that's the way I like it. 
So the moral of the story is: it's all subjective, 6/4 in comparison is a little stronger than 3/2.5 and so can be made to be a little lighter in the frames total weight, with the same strength as a 3/2.5. But that doesn't mean you'll like it more or less. Some people sware buy 6/4, some 3/2.5, some love steel, some carbon. Only you can answer this question. there is no right or wrong answer. Is it $500 better? For me, yes. Is butted 3/2.5 $500 better than straight gauge? For me, yes. That's just cuz I foolishly part with my money just so's I can see that really cool Reynolds 6/4 badge, it haunts me..and beauty is in the eye of the beholder....


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## Kerry Irons (Feb 25, 2002)

*Apples and apples*



Mark McM said:


> Frequently, 3/2.5 frames are lighter than 6/4 frames. Take for exampl the Litespeed Ghisallo, which is the lightest frame Litespeed makes. According to the 2006 web page, the Ghisallo is a mix of 6/4 and 3/2.5, while the Vortex is all 6/4 - and yet the Ghisallo is lighter. I'm pretty certain the 2005 and earlier Ghisallos were all 3/2.5 (although Litespeed probably couldn't admit that because then they would have to explain why it was both more expensive and lighter than their 6/4 frames).


The Ghisallo is known to be a frame that pushes the weight limits at the expense of being fairly flexy. Many heavier/larger riders find it too whippy. The Vortex is a very solid bike - different design goals and different results. It is not the choice of Ti alloy that drives this weight difference. The LS web site doesn't talk about alloys it seems, but IIRC the original Ghisalo was 6/4, except maybe the dropouts (like the Vortex).


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## Mark McM (Jun 18, 2005)

Kerry Irons said:


> The Ghisallo is known to be a frame that pushes the weight limits at the expense of being fairly flexy. Many heavier/larger riders find it too whippy. The Vortex is a very solid bike - different design goals and different results. It is not the choice of Ti alloy that drives this weight difference. The LS web site doesn't talk about alloys it seems, but IIRC the original Ghisalo was 6/4, except maybe the dropouts (like the Vortex).


If you look at the previous year's bikes (links available on the Litespeed web page), you'll see that prior to the 2007 models, the titanium alloy for the frames is noted for each model. Except for the Ghisallo, that is - the alloy is for the original 2002 - 2005 model is not stated, and for 2006 it is stated to be a mix of 6/4 and 3/2.5. In a thread earlier this year, a Litespeed insider stated that the original Ghisallo was indeed 3/2.5: http://forums.roadbikereview.com/showthread.php?t=57368&highlight=ghisallo+3%2F2.5+6.4.

_Theoretically_, since 6/4 is a stronger alloy, a 6/4 bike can be lighter. But in practice, this isn't always the case. A primary reason is that all the shaping, tapering, etc. necessary to shave weight is more difficult to do in 6/4. Which is probably why the lightest titanium frames, such as the Litespeed Ghisallo and the Merlin Magia, are made of 3/2.5 instead of 6/4.

Great bikes can be made from either material - but stating that "6/4 is stronger so 6/4 frames will always be lighter because they can use less of it" is just plain wrong.


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## Pepe (Jun 24, 2004)

Mark McM said:


> Diamond is the word's hardest substance - but you can't build a bike from it
> .


But a diamond is made of carbon!


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## blandin (Jan 9, 2005)

Pretty comprehensive article on Titanium and its use in bicycle frames.

http://www.bikepro.com/products/metals/titan.html


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## Juanmoretime (Nov 24, 2001)

Mark McM said:


> If you look at the previous year's bikes (links available on the Litespeed web page), you'll see that prior to the 2007 models, the titanium alloy for the frames is noted for each model. Except for the Ghisallo, that is - the alloy is for the original 2002 - 2005 model is not stated, and for 2006 it is stated to be a mix of 6/4 and 3/2.5. In a thread earlier this year, a Litespeed insider stated that the original Ghisallo was indeed 3/2.5: http://forums.roadbikereview.com/showthread.php?t=57368&highlight=ghisallo+3%2F2.5+6.4.
> 
> _Theoretically_, since 6/4 is a stronger alloy, a 6/4 bike can be lighter. But in practice, this isn't always the case. A primary reason is that all the shaping, tapering, etc. necessary to shave weight is more difficult to do in 6/4. Which is probably why the lightest titanium frames, such as the Litespeed Ghisallo and the Merlin Magia, are made of 3/2.5 instead of 6/4.
> 
> Great bikes can be made from either material - but stating that "6/4 is stronger so 6/4 frames will always be lighter because they can use less of it" is just plain wrong.


The 2006 Ghisallo still is 3/2.5 tubing. Litespeed claims it was light not 6/4. 

I've ridden the 2006 Ghisallo and with the tube manipulations done by Litespeed, and the compact geometry, It is every bit as stiff as my Vortex. While the early versions of the Ghisallo where noodles, Litespeed did do an excellent job of making the frame much stiffer.


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## elviento (Mar 24, 2002)

When we were down in Chattanooga a year ago, the gentleman who showed us around the factory said they did not have 6/4 seamless tubing and had to bend 6/4 ti sheets and weld them into (seamed) tubing. The Ghisallo does appear to have roundish tubing so most likely 3/2.5. 



Juanmoretime said:


> The 2006 Ghisallo still is 3/2.5 tubing. Litespeed claim it was light not 6/4.
> 
> I've ridden the 2006 Ghisallo and with the tube manipulations done by Litespeed, and the compact geometry, It is every bit as stiff as my Vortex. While the early versions of the Ghisallo where noodles, Litespeed did do an excellent job of making the frame much stiffer.


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## Nessism (Feb 6, 2004)

Lots of good info in this thread. It gets old when people wrongly talk about the superior nature of 6/4 which is just not true.

One thing of note though, seamed/welded tubing is just fine. True Temper tubing is as good as any and it's seamed.


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## Mark McM (Jun 18, 2005)

*6/4 titanium in Litespeed Ghisallo*



Juanmoretime said:


> The 2006 Ghisallo still is 3/2.5 tubing. Litespeed claims it was light not 6/4.


You are mistaken. The Litespeed web page for the 2006 Ghisallo (http://www.litespeed.com/bikes/2006/road/ghi_tech.aspx) clearly says, "Frame Material Blended 6/4-3/2.5 Titanium." Since only the diamond shaped top tube is non-round, it is probably a pretty good bet that only top tube is 6/4. In prior years however, the Ghisallo probably was competely 3/2.5.


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## LyncStar (May 1, 2005)

Mark McM said:


> You are mistaken. The Litespeed web page for the 2006 Ghisallo (http://www.litespeed.com/bikes/2006/road/ghi_tech.aspx) clearly says, "Frame Material Blended 6/4-3/2.5 Titanium." Since only the diamond shaped top tube is non-round, it is probably a pretty good bet that only top tube is 6/4. In prior years however, the Ghisallo probably was competely 3/2.5.


At the end of the day, it sounds like 6/4 is pretty much a marketing scam, like so many things in commerce/consumerdom.


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