alu vs. titanium

wildmoustache

the alu vs. carbon thread is ticking along nicely ... so why not start this one up.

a more interesting question is alu vs. titanium. why? because we all agree that carbon has a better stiffness to weight ratio than alu, and that carbon can be formed into shapes that is very difficult, perhaps impossible on a commercial basis, to do with alu ... and therefore the ride can be nicely tuned with carbon frames.

So ... what about titanium? Even mid-market Ti framesets cost about 2 or 3 times high-end alu framesets (both of which usually feature a carbon fork). What qualities does Ti have that alu doesn't to justify this premium? Weight is about the same ... perhaps a bit lower with Ti but not much ... Ti frames typically down to about 1200g and alu down to about that also.

giant_man

Oh nice follow-on wild moustache. Should make for a good debate.

campagsarge

I have heard a good Ti frame is for life, whereas the fatigue on an alu frame sets in quicker? Is this correct?

Iain Roche

as luck would have it i have also done a little blog about carbon and ti.

http://www.sundaybicycles.co.uk/ssblog.php

and click on June. its entitled carbon or Ti............


Iain

wildmoustache

Iain - your blog is interesting certainly. but it doesn't really answer the question I've put to the forum here.

woody-som

Ti is for life, no fatigue which is why it's used to structural parts of planes, and has the comfort of alu or steel, over carbon, which is generally known as a stiff and sometimes unforgiving ride.

Ti also over alu, or carbon has the advantage that it's not easy to damage it. Litespeed IIRC had a video on there site showing a lorry driving over alu, carbon and Ti, guess which took the weight and stayed in shape?

wildmoustache

Is it true that Ti doesn't fatigue?

Commercial airliners eventually are scrapped ... when the airframe is too old. Other parts (often alu) are replaced periodically.

Carbon is known for ranging from harsh to comfortable

Is having a bike that survives a lorry rollover incident a benefit? Actually, I very much doubt any Ti frame would be rideable after this despite Litespeed's creativity.

Iain Roche

“aluminium” is not a material suitable for bikes. Neither is pure titanium. Alloys of aluminium and other components can make great bike frames, as can alloys of Ti. “carbon” too is not a material in its own right.

I appreciate that I am being a little pedantic, but my point is I think it is unfair to relate all frames made from an aluminium alloy with A another material. The scope is just too big. But your all right in saying there are some generic properties that are true for the majority of that family of materials.

In terms of production costs for Ti over alu products it can be broken down to the following.

Raw material costs
Fabrication costs (cutting, joining, finishing)


For Ti products, these are typically higher than most of the commonly used aluminium alloys.

Jez mon

Do you regularly pressurize/de-pressurize your bike frame? In that case you need a Ti frame. Correct me if I'm wrong but the magnitude of strain that an aircraft face are greater than what a bike would face.

Furthermore, the lifespan of an aircraft frame is well....long, there are 30 yo 747s in the sky. Do you really plan to keep hold of a bike for 30 years anyway?

campagsarge

I notice that Sunday have a review of one of their bikes on this website.

I am no engineer at all so forgive my ignorance but don't all metals have a fatigue life? Do Ti frame builders offer a guarantee for life or just a standard 3 year one?

I will watch this thread with interest as whenever the day comes for my next frame purchase Ti will be high on the list - mainly for its strength.

I would hate to buy a £1,500 carbon beauty for it then to crumple in a crash.

wildmoustache

Iain Roche wrote:

“aluminium” is not a material suitable for bikes. Neither is pure titanium. Alloys of aluminium and other components can make great bike frames, as can alloys of Ti. “carbon” too is not a material in its own right.

I appreciate that I am being a little pedantic, but my point is I think it is unfair to relate all frames made from an aluminium alloy with A another material. The scope is just too big. But your all right in saying there are some generic properties that are true for the majority of that family of materials.

In terms of production costs for Ti over alu products it can be broken down to the following.

Raw material costs
Fabrication costs (cutting, joining, finishing)


For Ti products, these are typically higher than most of the commonly used aluminium alloys.

point taken ... it's real world comparisons that are important ... so, for example, what is the case for buying a Ti frame over a high-end Specialized or Canondale alu frame?

I understand the costs point ... but it's how the final product differs ... and whether that justifies the higher cost that is the interesting question

cougie

I have a carbon bike that i like.

My only concern is that it flies in a bike bag once a year or so for races, and maybe more if I get my act together for a training camp abroad.

Now if i had a titanium bike - I'd not be as concerned about flying with it. Then again - its survived half a dozen flights intact, but Ti would be hardier. Hmmmm.

redddraggon

campagsarge wrote:

I would hate to buy a £1,500 carbon beauty for it then to crumple in a crash.

I've crashed my carbon frame 3 times in the past weeks - no damage to the frame. I knackered the mech hanger/assos shorts/mobile phone/right ergo/bar tape and I got loads of road rash.

The damage that would write off a carbon frame would also probably damage a frame of the other materials.

Garry H

woody-som wrote:

Ti is for life, no fatigue which is why it's used to structural parts of planes, and has the comfort of alu or steel, over carbon, which is generally known as a stiff and sometimes unforgiving ride.

I've never heard anyone refer to carbon as an "unforgiving ride", stiff yes but it's not unforgiving. I'd say that carbon is a more comfortable ride than alu alloys, all else being equal.