Wednesday, August 30, 2006

Materials of Choice: Titanium

If Aluminum is the flavor of the day for bike frames, and steel was the former champion, then titanium has to be the modern "wonder metal" that garners "oohs" and "aahhs" whenever we see a frame made of the silvery-grey stuff. Titanium hasn't been used in bicycle frame construction on a wide scale until recently. In fact, mountain bikes made of the stuff didn't arrive on the scene until steel and aluminum frames were rather common place. There are some rather odd details to the story of titanium, so let's take a closer look.

Pictured: A classic titanium mountain bike frame; the Moots YBB

If you think that I might have some homework for you to read, you're right! Take a look at this short article on titanium and it's alloys. You might be surprised to know that there is more titanium alloys than you thought! As with aluminum and steel, titanium gains desirable qualities if it's alloyed out with the correct materials for bicycle frames. "Commercially Pure" titanium, or "CP" as it's more commonly known, is a little too boingy for most folks taste. So to stiffen things up a bit, and to keep the frame tubing stronger, a little bit of aluminum and vanadium is thrown into the mix. (Read the article for a better explanation) At any rate, most titanium frames that you see today are made from this alloy of titanium: 3 Al- 2.5V, which describes the "recipe" for the alloy.

Titanium hasn't been used for bicycle frames for a few reasons until recently. Number one probably has to be because of it's high demand in the aero-space industry and in particular, the defense industry. The silvery-grey stuff is light and strong so it's a no brainer for applications in that field. Add to it the high resistence to corrosion and you have a highly coveted metal. The crazy thing is, titanium as an element is not rare! It's the ninth most common element on earth. So what's the dealio? Why is titanium so hard to get and so pricey? Well, that's a whole 'nuther story there, mate! To keep this post in check, you should read this. The short answer is, it's dang tough to get it out of it's natural mixed-up-with-other-substances state. You see, there are not any naturally occuring pure titanium deposits. So, it's a tough, expensive, time consuming process to get the titanium extracted. That's why it's been awhile since the metal was considered for anything other than aero-space/ defense use.

Titanium: Spendy, flexy, and not designer friendly. Lasts forever. Rides like nothing else and is lighter than anything. These are the things commonly heard about the wonder metal. True or false? Let's look!

Spendy: Yep! Confirmed. Yet, as the second linked article indicates, it might not always be the case.

Flexy: Uh-huh. Yeah, but it can be made to be somewhat less whippy and flexy with very careful design and use of it's sister alloy 6Al- 4V, which is pretty stout but harder than heck to work with. Regardless: big fellows and mashers take note, if ya likes yer frames stout and stiff, ya might steer clear of this grey matter!

Not designer friendly: No. Period. It's hard to work with, it's expensive to purchase, and their are only straight guage and one butted tube choice for builders to choose from. Tuning the ride is far more difficult to do. Most of the time, it's simply compromised for the cool factor.

Resists corrosion: Yep! Rides like nothing else: Yep again, but that's not always a good thing! Light: Yes again, but not the lightest. Care must be taken with Ti to keep the stiffness, so making it light, while entirely possible, is usually counter productive. You end up with a light bike, but it's a flexy P.O.S. !

So, is titanium for you? Maybe. If you ride smoothly, are medium to small in stature, have a healthy bank account, and don't mind a bit of flex in your steed, then go right ahead. Maybe you have fallen under the siren song of the mysterious grey metal. Whatever it is, titanium seems to have a strong following and always gets the stares. Modern technology may prove to be a boon to titanium in the recovery of the ore and also in it's use in bicycles. Carbon fiber, when mated to this wonder metal, can be used to tune the ride. Some interesting work is being done by Titus and others in this vein.

Next: Carbon Fiber

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