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
24 Hall Rd.
Hillsborough, NH 03244
USA
603 478 0900 Phone
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