On Wednesday, November 22, 2017 at 8:20:56 AM UTC-8, Frank Krygowski wrote:
On 11/22/2017 12:53 AM, John B. wrote:

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.

Well, the closest topic to the subject I can find in Jobst Brandt's book
is regarding mirror image spoking of left & right flanges, vs.
identical spoking. He says the differences are so small that the debate
is entirely academic.

His detailed wheel building instructions have the pulling (i.e.
trailing) spoke heads on the outside, toward the cogs. That's how I've
always done mine. I almost never break spokes. BTW, I do use 36 spokes
in all my wheels, except 48 for the tandem's rear wheel.

I wonder if there's any mismatch between your troublesome hub's spoke
hole diameter and your spoke diameter? And are the hub's holes countersunk?

Just from a building standpoint, it's convenient to do trailing spokes head-out on both sides. No weaving spokes around or remembering patterns. I mix it up on front disc wheels, or at least I used to -- but even if I just build them identically on both sides, I haven't experienced any problems. I get spoke breakage when spokes have defects, or I used spokes get a set and then you re-use them with a different orientation or when nipples get cut by sharp rim holes.

-- Jay Beattie.