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Re: Carbon fibre v Titanium

Posted: 13 May 2010, 8:26pm
by minkie
People who own carbon bikes seem to fret a lot that relatively minor impacts may have compromised the integrity of their frame.

People who have carbon, ally or steel bikes seem to fret about their paintwork (or pretend they don't care when it gets scratched).

People who have titanium bikes are happy, carefree souls who don't have to worry about any of that stuff..........

Re: Carbon fibre v Titanium

Posted: 4 Jul 2010, 11:57pm
by Jonty
I've followed this thread with interest although I'm not a metallurgist. From what's has been said, I conclude that titanium is best if it's welded properly.
If Rolls Royce Aviation in Derby made titanium framed bikes, and I had a windfall on the Premium Bonds, I'd have one.
jonty

Re: Carbon fibre v Titanium

Posted: 7 Jul 2010, 2:37am
by BTP
al_yrpal wrote:As an engineer who spent a lifetime designing metal and plastic structures, reading some of the folklore here makes me smile.

Al


Here here.

The reasons that different bikes handle and ride differently is due to frame design. And frame design depends, in part, on the frame material chosen, as well as the use the bike will be put to (competition, touring, MTB etc etc).

For example, Aluminium actually has a lower modulus of elasticity (ie, bends more for a given force) than steel. The reason Aluminium frames feel stiffer and harsher is that they are designed to be so, by using oversized tubes. This reduces frame stresses thus increasing the fatigue cycle-life that is ever-present in Aluminum and associated alloys. But this in turn means a harsher ride.

Steel, titanium, aluminium and carbon all have advantages and disadvantages, but the first thought for a rider should be "What kind of bike do I want" and "how well does it fit me" rather than "what is it made of".

Contrary to what most are claiming here, I would suggest that titanium is not a difficult material to work with, just different. You have to be more patient and careful in cutting and welding the stuff. But there are plenty of aircraft flying with welded titanium parts that are no more likely to fail than any other weld.

Carbon is very light and strong, but I'm cautious of its failure mode. My local framebuilder has stopped building bikes now. He earns his money repairing carbon frames and his workshop is full to bursting with frames, many cracked/broken, requiring repair or just examination after an accident. At least with steel, Ti or Al, you get a bit of warning.

Cheers,