DT Spokes

In the year 2000, DT changed the design of their spoke ends. They've made the hooked end or elbow of their spokes about .85mm longer. There has been some confusion as to the reason for the change.

When I first noticed the change in late September, 2000 I called DT in Grand Junction, Colorado to find out what was going on. I was told by a sales person that Hugi hubs (which are manufactured by DT in Switzerland) are now being made with thicker flanges, and they wanted their spokes to be compatible with Hugi hubs. However, on November 1, 2000 I spoke with the General Manager of DT who told me that the change was made at the request of several of DT's larger customers, (who I assume build wheels not by hand, but by machine) and that in fact there had been no change in Hugi hub flanges and that none was planned. The large volume builders needed spokes that could be laced into the hub faster. The tight fit of the original spec spokes made lacing wheels slower.

That's all well and good, if your primary concern is the speed at which you can build the wheel, rather than the durability of the wheel. A tight fit of the spoke in the hub is important in preventing flexion of the spoke at the hub flange.

My most recent shipment of DT spokes with the longer elbows had the letter "R" on the label. R stands for revised. That, according to DT, is the way they are identifying the new spokes.

The sales person I spoke to at DT in Grand Junction, Colorado told me that they gave this matter a lot of thought and that they did not believe that the change will create any problems for wheels built with other hubs. My 25 years of professional wheelbuilding experience leads me to a different opinion.

You can see the difference in the two photos below. The top photo is the old spoke design, the lower photo shows the new. Both spokes are brand new, right out of the box.

This creates a huge problem for anyone building a wheel with DT spokes. The longer spoke end extends out from the hub flange and can flex under load, eventually causing it to break at the bend.

You can see that the new design puts the elbow at closer to 90 degrees than the old design. That's so builders don't have to bend the spokes to get the spokes to make a straight line from the hub flange to the rim. If you don't start out with a straight spoke, it will lose tension as you ride it, because the spoke will straighten with use. But they haven't put in enough bend to eliminate the need for the builder to bend the spoke, so all you end up with is a spoke that's more difficult to get through the hub flange while lacing, because the bend is sharper, and you still have to bend it later.

So what's a wheelbuilder to do?

One solution is to use a washer between the spoke head and the hub flange, taking up the space and preventing the spoke from flexing. DT happens to sell such washers. I will be doing this with those DT spokes I recently received that have the new specification end, about 15% of my inventory. This adds greatly to the time it takes to build a wheel, and in the long term is not economically viable. But the wheel is just as strong and reliable as when built with the old spec DT spokes, so all wheels built with washers will still have my lifetime guarantee.

Still another solution is to use different spokes. This is the solution I have implemented. In December, 2000 I bought a Phil Wood spoke cutting machine so that I can efficiently use up my remaining stock of DT spokes. I have well over 10,000 DT spokes in stock. I have a huge range of lengths, and I stock seven different types of DT spokes. It adds up fast.

For instance, when my inventory of 296mm 15 gauge spokes gets below the amount I need to build a wheel, I'll take some longer spokes of the same gauge and shorten them on the Phil Wood cutter to complete the wheel. As time goes on, I'll reduce my spoke inventory to about 2,000. As I need longer lengths to build wheels, I'll replace the inventory with Wheelsmith spokes, which I'll have in stock by about the middle of January. I will get in unthreaded spokes and cut them to the length I need with the Phil Wood cutter. The reduction in spoke inventory will more than pay for the Phil Wood spoke cutter, which costs over two thousand dollars.

So when you order a wheel from me, it may come with DT spokes without washers, or DT spokes with washers, or with Wheelsmith. But most importantly, it will come with my lifetime guarantee.

As a result of inquiries and complaints from builders like me and many others, DT has now decided (2001) to change the specifications on their spokes again. They will be shortening the elbow length, not all the way back to the original spec, but most of the way.

The original specification for the elbow length for a 2.0mm or 14 gauge spoke was from 6mm to 6.2mm, or 6.1mm + or - .1mm.

The specification for the revised spoke is 6.8mm, + or - .1mm.

The specification for the next revision will be 6.3mm, + or - .1mm.

So, when all of this shakes out, DT spokes will have an elbow section .2mm longer than they did originally. The second revision, back to a shorter elbow will be in effect as of January 1, 2001. But it could be several months before those spokes will be at your friendly local bike shop. And in the mean time, DT is still shipping spokes with the longer elbow, and maintaining their position that the spokes are fine.

Well, they're fine as long as the builder uses washers to take up the slack. And DT does have washers available for that purpose.

In defense of DT, there are some circumstances when a longer spoke elbow would be useful. The latest version of Shimano's Dura Ace rear hub (the nine speed 7700) has a slightly thicker right flange than their other hubs. Lacing up a Dura Ace wheel with a 14-15 butted DT spoke takes an extra two or three minutes, because you have to wrestle with the spoke a bit while lacing it through. I've found that Wheelsmith spokes lace up much easier in the new Dura Ace hub than DT, and have a nice tight fit once they're laced. The Dura Ace hub was mentioned by the DT General Manager as a source of complaints by some builders, and one of the reasons why they lengthened the elbow.

But the new longer elbow DT spokes still take longer to lace into a Dura Ace hub, because the corner is sharper for instance than on a Wheelsmith spoke, and there is still .4mm of lateral slop in the fit once the spoke is laced. The Wheelsmith DB14 fits the Dura Ace flange much better than the DT 14-15 spoke, regardless of vintage.


Update!

Update, May, 2006. This is now very old news. I no longer have any butted DT spokes to build with. All I'm using these days are Wheelsmith. I decided to stay with Wheelsmith because the way they form the heads results in a very smooth transition between the head and the rest of the spoke. The DT heads look like a triangle when viewed from the side, and there's a sharp angle at the base of the head. Wheelsmith heads are rounded, there's no sharp angle. That sharp angle is a stress riser, which can and does occasionally cause the heads of DT spokes to break off, even with the proper elbow length. These are two different issues. The 2000 spec spokes were breaking at the elbow. But DT spokes have always had a very slight tendency to have the heads pop off, right at the base of the head. I don't mean to make a big deal about this. The number of failures is quite small, because in fact the heads of spokes in a properly built wheel are not subject to very high loads. But they are subject to some load, otherwise there would be no need for a head. ;-) And I have seen several dozen DT spokes with the heads popped off. This doesn't happen with Wheelsmith spokes because there is no stress riser at the base of the head. So, even though DT no longer makes their spokes with excessively long elbows, I'm staying with Wheelsmith, because of the design of the heads.

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This page updated: Wednesday, September 26, 2007

Peter White Cycles
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