Specialized Bottom Bracket


This bottom bracket represents the third incarnation of a Titanium spindled bottom bracket from Specialized in as many years. The first we saw was one called the "Direct Drive" and was going to be made we were told in Japan. It seems that the intended maker and Specialized may not have come to terms with what the B/B should be. More likely the cost of the work done in Japan became considerably more expensive than was first expected.

At the time we first saw the DD B/B, the dollar was trading at around 150 yen to the dollar. Presently it is at 101, representing roughly a 33% price increase and it would still have to compete against American makers who were capable of doing the work more cheaply. Remember also that there is no Japanese manufacturer of bike parts yet, who has made a reputation for machining Titanium alloy into finished parts (the Japanese have historically used Commercially Pure titanium for their bike parts, when they used it at all). So it may also be that their supplier of Cro-Moly spindled bottom brackets, (whom we believe to be Sugino), wasn't capable of or genuinely inclined to make a Ti spindled model for them.

The first Titanium spindled model came late in 1991 and was called the "Direct Drive Bottom Bracket". Instead of sourcing it from the orient, Specialized got in touch with Doug White of White Industries in Novato, California. White Industries is known for having made the finely engineered "Phantom" bottom bracket. An arrangement was made between White and Specialized for similar boxes to the Phantom's manufactured with Specialized's scripting on them, and the Phantom B/B was modified so that the aluminum parts were Black anodized and a Specialized logo was engraved in the outer face of the cups. No functional, mechanical, or engineering differences were noticeable between the White Phantom and the Specialized Direct Drive.

We are told that sometime after the Direct Drive B/B, made by White, was on the market, TNT Performance Products of Phoenix, AZ contacted Specialized and pitched them on the idea of TNT building a B/B for them as a variation on their Ultimate Competition series of bottom brackets. Specialized was receptive and the current model of Titanium spindled bottom bracket is, in fact, designed by TNT, machined by sub-contractors, and is indeed a variation on the Ultimate Comp B/B. What follows is a description of the TNT made B/B.


The Specialized Titanium B/B as explained above is made in the U.S. by TNT in Phoenix, AZ. It is a dual adjustable cup with fixed length spindle type of bottom bracket, with the spindle position adjusted through the placement and position of two adjustable bearing cups. The bearing cups are machined from 7075-T561 aluminum alloy rod to create a thin walled, precisely fit cup. The outer face of the cup has four equidistant 3mm diameter holes bored into it, so a pin spanner like the Green Park SPA-1 can be used to give the cup a final tightening. One cup also has two "S" logos engraved in it. At the hole where the spindle exits the cup, there is a milled channel within the edge that houses an O-ring to seal contaminants out.

As mentioned in the TNT description, the Specialized model has this O-ring installed where the TNT model does not, though the channel exists for the O-ring on the TNT models. The feature of having the O-ring installed was granted to the Specialized version exclusively, to afford them a distinction between two obviously similar products. Both of the lockrings are machined from aluminum alloy and have six square shaped notches cut equidistant around the perimeter of the ring for a hook spanner to grip for final tightening.

The spindle is machined from Ti 6Al-4V rod. It is drilled through to reduce its weight, then the ends are tapped for the crank bolts. The center area between the bearings of the spindle is reduced on the lathe to a diameter, established with the help of Brett Dixon at Specialized of 650/1000ths of an inch. It is slightly larger than the TNT model and is said to be so to achieve "maximum stiffness", according to the packaging. Wouldn't solid really be even more maximum? The precision sealed bearing cartridges chosen for this B/B are the Japanese IJK 6903RS. They are pressed onto the spindle and rest against a shoulder machined by lathe onto each end of the spindle.

This B/B also comes with what we believe to be some of the greatest aluminum machine work as a pair of one-piece crank bolt/washers. This is the same crank bolt set that has with TNT bottom brackets for the last few years and weigh 10.5 grams per pair. It is recommended that you tighten the cranks onto the spindle with steel bolts, remove them and then use the aluminum to hold them onto the spindle. The Specialized Titanium bottom bracket, and the TNT version it's derived from come in many models to suit different B/B shell width and spindle lengths.

For mountain bike use there are three models to fit a 68mm wide B/B shell; 107mm (to fit the new XTR cranks), 117mm (to fit Micro Drive cranks of all makes), and 122.5mm (to fit standard XT cranks and the now discontinued DX cranks). There are four models of mountain lengths to fit a 78mm wide B/B shell; 107mm (to fit the XTR), 111mm (to fit the XTR and LX cranks), 117mm (to fit Micro Drive cranks of all makes), and 122.5mm (to fit standard XT cranks and the non Hyper-C cranks).

There are also two road models intended to fit only 68mm wide B/B shells, both have a 112.5mm long spindle, their distinction is that one is English and the other is Italian threaded. The weight of the Specialized Titanium with a 122.5mm long spindle to fit a 68mm wide B/B shell is 164 grams.

68mm shell English Spindle Length-07-12-17-22 / E $Price in Catalog
73mm shell English Spindle Length-07-11-17-22 $Price in Catalog
68mm shell ItalianSpindle Length-12 / I $Price in Catalog

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