Spokes - again

Owen said:

Just done my eighth spoke.

They are all on the non cassette side and all have their heads on the
inside. One more to go!

Just curious as to if anyone has any opinion as to why just these
spokes have broken. Maybe the big machine in Taiwan just stuffed that
set of nine when they were making it.

Do you have a pannier rack/fender bolt which is a touch to long and
nicks the spokes?

<pure guesework>
Non-cassette side are tensioned less and so will lose tension easier
then the cassette side, and the neck of the spokes probably haven't
been bent in to meet the hub.
</pure guesework>

Cheers

Joel

On the subject of broken spokes I am confused. I was told that spokes
break because of fatigue caused by repeated flexing in much the same way
a coat hanger can be broken by bending back and forth. And a wheel
without evenly tensioned and tight spokes will suffer more broken spokes.

I seem to suffer more broken spokes on the cassette side, and I always
thought it was because the spokes were tighter because of the need to
dish the wheel. But some "experts" told me it was because the dish
created a spoke angle more nearly perpendicular to the hub flange and
hence there was a greater tendency to side-side flexing and hence broken
spokes. But then the other hub flange must surely move side-side the
exact same amount as the cassette side, so what is the truth?

Also I am very heavy so I am not surprised I break spokes, but one of
the above mentioned "experts" I know also breaks spokes and is a
featherweight compared to me.
Regards Wilfred.

Joel Mayes said:

Owen said:

Just done my eighth spoke.

They are all on the non cassette side and all have their heads on the
inside. One more to go!

Just curious as to if anyone has any opinion as to why just these
spokes have broken. Maybe the big machine in Taiwan just stuffed that
set of nine when they were making it.

Do you have a pannier rack/fender bolt which is a touch to long and
nicks the spokes?

<pure guesework>
Non-cassette side are tensioned less and so will lose tension easier
then the cassette side, and the neck of the spokes probably haven't
been bent in to meet the hub.
</pure guesework>

Cheers

Joel

Wilfred said:

On the subject of broken spokes I am confused. I was told that spokes
break because of fatigue caused by repeated flexing in much the same way
a coat hanger can be broken by bending back and forth. And a wheel
without evenly tensioned and tight spokes will suffer more broken spokes.

As the wheel rotates the spokes at the bottom have the tension released,
especially if you hit a bump. Then as they move back up the wheel the
tension comes back on. On a nice tight wheel there is no real movement,
but on a loosely spoked wheel this results in a slight flex of the spoke
head in the flange.

Normally the drive side has higher tension spokes, at a steeper angle so
that the wheel is centred in the dropouts, not between the hub flanges.
You will get some wind up effects from pedalling and braking, but the
higher variation between tension and detension is probably the culprit in
your case.

Either get your wheel relaced by a clueful wheelbuilder, or DIY according
to Sheldon's instructions. That's how I learned to build a wheel, and all
the ones I've done are still going well.

Quoted message said:

Also I am very heavy so I am not surprised I break spokes, but one of
the above mentioned "experts" I know also breaks spokes and is a
featherweight compared to me.

I'm only 75kg, but I'm nasty to my wheels. The back wheel of my playbike
was built in about July '02 and is still basically straight and running
the original spokes, despite lots of landings not quite aligned with the
direction of travel. The only time I've broken spokes on wheels that were
properly tensioned is through stick incidents. I also regularly ride with
blokes who are 100kg+ and their wheels are similarly bombproof.

--
Dave Hughes | [email hidden]
There's no point in being grown up if you can't be
childish sometimes.-- Dr. Who