On 11/23/2017 3:13 AM, John B. wrote:
On Wed, 22 Nov 2017 09:44:38 -0000, "Graham"
wrote:


"John B." wrote in message ...

I'm rebuilding a rear (derailier) wheel as, to be frank, I used spokes
that were slightly smaller in diameter on the cassette side of the
wheel then probably wise, and had occasional spoke breakage. I finally
got some slightly larger diameter spokes and am lacing the cassette
side of the wheel.

Over probably a couple of years I had four spokes break, one at a
time, all were what Sheldon referred to as trailing spokes, the ones
that have the highest strain when pedaling, and all broke at the
middle of the bend at the head end.

While I was lacing the wheel with the new spokes I got to wondering
whether the side of the hub flange that spoke heads were on might have
had any effect on strength.

I have always laced 36 hole wheels over three for rear wheels and over
two for front wheels with the trailing spoke heads on the outside of
the hub flange and the leading spokes with the heads on the inside of
the flange, as I believe that Sheldon recommended.

But I also remember someone here with a rant about rear wheel lacing
who I think was recommending that on the cassette side that the heads
should all be toward the outside of the flange. I assumes to prevent
damaging spokes if the chain were to come off the largest cassette cog
and jam between the spokes and the cassette.

This is the only wheel I've had problems with and I deliberately
bought the bits and pieces with the idea of long life in mind -
cartridge wheel bearings and medium weight rim with eyelets, etc., and
as this is the only wheel that I've had problems with I'm fairly sure
that my wheel building technique is reasonably effective.

Any thoughts on spoke head orientation and the effect on spoke
strength.

--
Cheers,

John B.

FWIW I have always used the method described in Gerd Schraner's book on wheel building and I have no problems with wheels going out of true or spokes breaking. Schraner discusses your point and concludes that in his opinion it does not much matter whether the spokes at the hub are laced in a symetric or mirror image pattern or whether the driving spokes are head out or in. From his long experience of wheel building he has concluded that there should be a very marginal gain to have the driven spokes heads in on the cassette side and that is what he recommends. His logic being that it very slightly increases the angle to the rim and thereby slightly reduced tension. However it is clear he would not get into a flame war over it. His main contention is that it is the quality of the components and the build that determine how a wheel performs. On spoke elbow breakages he stresses the need to bed the spoke heads into the hub and to correctly tension and stress relieve the wheel.

Graham.


I tend to agree with you as I've built wheels in all sorts of style
and have seldom had any problems which was what was puzzling with this
particular wheel. It was straight and would go for months and then
pop, one spoke on the drive side would pop the head off and the wheel
would wobble. I'd take the wheel apart and check everything change the
spoke and re tension and it would go for months and then pop. The last
time it popped two spokes about 180 degrees from each other and I
decided to do something a bit more permanent and replaced all the
drive side spokes with a thicker spokes.

About thicker spokes: I do believe that butted spokes (thinner in the
middle) make stronger wheels.

When building new wheels before our biggest tour, IIRC I got butted
spokes with extra thickness at the end with the head. Sorry I don't now
remember the brand or gauge. It's been a long time.

I could go measure measure, but I'm late heading for a big dinner.


--
- Frank Krygowski