The Wonders of 'Ti'

Image - Baum Cycles

Michael Hanslip slips on his welding goggles to delve into the world of Titanium manufacturing, providing a background and discussing why the material is so desirable for bicycle frames.

When it was discovered over two hundred years ago, Titanium (abbreviated Ti) was named for the ‘Titans’ of Greek myth because of its exceptional combination of strength, low weight, and resistance to corrosion.

In its natural state, Titanium ore contains Titanium combined with Oxygen, usually in the form TiO2. To transform TiO2 into a structural metal the oxygen must removed.

With most metals this can be accomplished simply by heating in an oxygen-free atmosphere, but Ti either combines with whatever other gas is around or refuses to release the O2. The solution is to transfer the oxygen onto magnesium, which ‘ruins’ another perfectly good refined metal that itself is not inexpensive.

With this complexity a suitable commercial refining process wasn’t developed until after World War II (the same process is still used, but more on this in a minute). As a result of this difficult and costly refining process Titanium has always been, and probably always will be, comparatively rare and expensive despite the fact that deposits of Titanium ore are found all over the world.

Its attractive properties and its limited availability meant that the first uses of Titanium were limited to highly sensitive areas such as jet aircraft components. Only recently has there been enough Titanium available to make the transition to other applications such as high-end sporting goods, including bike frames.

Super Strong & Light

It is worth all the effort and electricity because the resulting pure Ti has the strength of steel at two-thirds the weight. About thirty years ago the Teledyne Titan was one of the first successful Ti bike frames on the market, but it was perhaps a bit before its time and not able to take advantage of the best Titanium alloys that are now available. As a result it didn’t last on the market.

Since about 1990 the Titanium used in bikes has been alloyed with Aluminium and Vanadium, to further improve its strength to weight ratio. Check out just about any current Ti bike frame; and it will be made of either 3/2.5 or 6/4 Titanium alloy. These numbers refer to the percentage of aluminium and vanadium respectively. The 6/4 stuff is roughly twice the strength of pure Ti at the same weight!

Once it is purified and alloyed the real work of crafting Titanium is just beginning. It is incredibly springy stuff, so manipulating it into tubes requires big, expensive machinery careful planning, and experience. Working with plain gauge tubing (tubes with equal wall thickness from one end to the other) was the only choice for the bike industry in the early days as the Titanium pioneers used tubes that were originally designed to carry rocket fuel or avgas in some aerospace application. Even with these early bikes, cyclists were quick to notice Titanium’s ride qualities, and now legendary durability.

Whilst 3/2.5 alloy could be cold worked into new shapes (such as butted tubes or non-round tubes) 6/4 alloy was so tough it couldn’t even be drawn into tubes. That is right; at least until recently, all the super-expensive 6/4 frames on the market started life as flat sheets of Ti that were rolled and then welded to make tubes. This is indicative of the amount of work that goes into making some Titanium bikes. Cut the sheet, roll the piece, weld the seam, and buff the weld out (to the point that it is usually invisible).

Manufacturing Challenges

Even if the frame builder can assemble the right collection of tubes to become a bike, still the difficulties in working with Ti are not over. Titanium is so tough that cutting tools that usually last for several months on steel tubes (and much longer again on soft aluminium) might last through only a few Ti bikes. No, that’s not a few months, just a few frames.

Welding is also a big issue (thankfully, the last one). Earlier I mentioned that all Titanium ores contain oxidised forms of the metal. This is because when you heat up Ti, even a little, it sucks up oxygen like a big sponge. Consequently the welding process must be carefully designed to prevent the Ti recombining with Oxygen or other gasses in the atmosphere.

The process that works best for bicycle construction is to flood the welded area with Argon gas. The Argon itself is inert, so it’s one of the few gases that will not combine with hot Titanium, and provides the added advantage of assisting with controlling the temperature of the weld. Using flexible hoses to supply the argon also allows excellent access to the joint to allow smooth consistent welds to be produced.

Some of you may have started thinking that Titanium seems a bit esoteric and irrelevant to the bike business even before the manufacturing challenges. Besides, isn’t everything new done in carbon these days? Whilst it is true that we are in some sort of carbon-age for frames and just about everything else (bars, stems, forks, cages, seat posts, saddles, rims, cranks and shoes) there are forces at work that could change this, at least slightly, in the near future.

Mainstream Ti?

The first issue is the supply and demand of carbon fabrics and carbon fibre experts. Whilst there is a lot of carbon on the market there is a relatively limited availability of high-quality carbon and the expertise necessary to engineer and manufacture bikes. This is partially the result of increasing demand from the military, and the aircraft industry switching over to carbon fibre (from Aluminium) to reduce the manufacturing cost and increase the fuel economy of their own products.

These industries that that sell their products for a few hundred million dollars each are in a much stronger position to control the market for the best experts and the best materials available than the relatively small bicycle industry. Just as in the early days of Titanium, bikes might be left with limited options; especially if new factories don’t come online fast enough. Will it happen? Who knows, but there’s already one European carbon factory with 100% of its 2007 output pre-sold to French aircraft manufacturer Airbus!

The second issue is that there is word of a potential new Ti refinement process. Titanium ore could be refined into pure Ti more efficiently or the new processes could be used to create even better Titanium tubes.

Overall, there might be a bit of a shift in the bicycle industry; carbon fibre products pushed to lower quality or higher prices, and Titanium moving to higher quality or lower prices.

When it comes down to it, the real attraction of Titanium is how the finished frames ride. I have owned three Ti bikes and can state unequivocally that they offer an exceptional ride quality and fantastic durability. My commitment to Titanium is even demonstrated by my Ti wedding ring! These qualities keep people buying Titanium bikes, especially as there are a range of smaller builders—including local companies—who can make you an excellent (if expensive) custom Ti bike.

Traditionally based in the USA, there are now a number of Titanium frame builders in all of the major cycling regions with companies such as Argon18, Baum (based near Geelong, Victoria), Enigma, Everti, Guru, Lynskey, Moots, Roark, Serotta, Seven, Spectrum, Titus, Omega, and many more.

For those of you looking for a traditional bike frame, steel tubes combined with lugs might be what you are looking for. If it’s a time-trial weapon you are after, it would have to carbon fibre for its ability to make slippery shapes, but if you want a bike to last a lifetime, to combine comfort and performance and low weight, not to mention good looks, Titanium is still number one!