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Titanium seems to be a great material to use for bike frames.

Why not for forks ? Does anybody make a Titanium fork?
 

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giosblue said:
Titanium seems to be a great material to use for bike frames.

Why not for forks ? Does anybody make a Titanium fork?
You don't want a fork that is noodly. It is also FAR cheaper to buy a CF fork nowadays, in addition to the weight/stiffness benefits.
 

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Marc said:
You don't want a fork that is noodly. It is also FAR cheaper to buy a CF fork nowadays, in addition to the weight/stiffness benefits.

Why good for frames. plenty stiff, not noodly.
No good for for forks?
 

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giosblue said:
Why good for frames. plenty stiff, not noodly.
No good for for forks?
1) Economics.

-CF forks are DIRT cheap to make. Just like CF frames-do you really think it cost TIME $5000 to make their frames? They are also light, stiff and reliable. Once you have a mold-you can mass produce CF forks quickly, and every one you make gets cheaper.

-Ti forks, like Ti frames require metal working which is expensive and time consuming. And every unit costs the same.


2) Metal properties

-Ti is lighter than steel but FAR less stiff. We're talking roughly 1/3 the weight, but also 1/3 the stiffness. To get a Ti fork that is as stiff as a steel fork-you'd need pipes that are FAR beefier (i.e. heavier).

Due to the economics a Ti fork would cost FAR more than a CF fork to produce, it would also weigh FAR more than a CF fork while not being as stiff. What advantage is there at all in Ti forks?


Remember a fork is nothing more than 3 pipes attached to one another-that is the limit of your structure. A bike frame has triangles and has natural stiffness and strength due to it's design. A fork don't.
 

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Marc said:
And with only 600g of weight, and a $600+ pricetag...it only weighs and costs 2X what a CF fork does. :)

Still purdy.
Steve Jobs calls it the iFork.
 

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Marc said:
2) Metal properties

-Ti is lighter than steel but FAR less stiff. We're talking roughly 1/3 the weight, but also 1/3 the stiffness. To get a Ti fork that is as stiff as a steel fork-you'd need pipes that are FAR beefier (i.e. heavier).
Well, it's actually closer to about half the density and half the stiffness. But you can get stiffness with geometry rather than adding material -- changing a tube's outer diameter is MUCH more effective (r^4) at adding stiffness than just making the wall thicker. So you could make a tube made of Ti (with half the material stiffness of chromoly steel) have the same stiffness just by making it 20% larger in diameter, and it would be (roughly) 60% of the weight. This is (basically) why aluminum frames are lighter than steel frames, even though aluminum alloys are typically not as strong or stiff as the steels used in bikes -- they use larger diameter tubes with a relatively thin wall. I'd be willing to bet you could make a Ti fork that was as stiff as a typical steel fork but ~30% or so lighter once you take in all of the engineering intricacies (like buckling strength). I doubt you could make one lighter than a CF fork though.

Fun fact: almost all common engineering metals (Steels, Al, Ti, Mg, etc) have more-or-less the same stiffness-to-weight ratio (beryllium is higher, I think). Carbon fiber composites can be much stiffer, depending on the fiber-to-resin ratio.

Asad
 

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asad137 has got the engineering stuff down pat; trust his numbers.

The problem with Ti is not just the fork blades would have to be larger than steel, but there may be clearance issues at the brake as a result. Another problem is, the spring rate properties of Ti aren't quite like those of steel, hence they tend to feel softer. There are several manufacturers of Ti forks in the USA. They're a niche product. If they were practical, you could bet there'd be a market for them. Personally, I'd use that clue that they're not worth it.
 

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I have a Ti fork for the road bike by Black Sheep. It has the heavier gauge tubes for the fork so its heavier than the standard fork. I never weighed it. I am guess its close to 550 grams vrs the 350 grams for the Eatson SL 90 I pulled. Yes, it is heavier than a carbon fork. Its rides very well and takes up to 28mm. (Which most carbon forks these do not.) What I have notice is that the vibration of the Ti fork is different than the carbon Easton I was running. It doesnt have that higher frequancy you get from carbon. So far so good. Carbon is good...so it Ti and steel if you make it right. You will always be lighter with carbon. But, sometimes I wonder if you could but 550 grams in to a carbon fork how stiff you really could make it or safer with more carbon in the steer tube. I think in the quest for lighter and lighter stuff, we went from making things last to making you by new carbon parts every few years. Its a bicycle not a formual one car. With all the torque specs these days on things its a wonder why there isnt more problems with all the carbon stuff. The Black Sheep fork is on my travel bike. I wanted something simple and I wont have to worry about the carbon fork in the case..
 
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