Spoke eating hub

I have an old Torpedo back hub, probably about 30-40 years old,
the good kind that are indestructable (well, almost). It works
well but it has one problem: it eats spokes. I crack one about
once a fortnight. I have had such a hub before, and I wonder what
does this? With the last spoke, the head broke off, leaving the
elbow intact, whereas the one before it broke off at the elbow.

What does this, and is there anything I can do about it?
--
Dieter Britz, Kemisk Institut, Aarhus Universitet, Danmark.

"Dieter Britz" wrote in message
...
I have an old Torpedo back hub, probably about 30-40 years old,
the good kind that are indestructable (well, almost). It works
well but it has one problem: it eats spokes. I crack one about
once a fortnight. I have had such a hub before, and I wonder what
does this? With the last spoke, the head broke off, leaving the
elbow intact, whereas the one before it broke off at the elbow.

What does this, and is there anything I can do about it?
--
Dieter Britz, Kemisk Institut, Aarhus Universitet, Danmark.


Steel hubs (I assume this is steel; I've never seen a Torpedo aluminium hub)
can be hard on spokes.

The flanges is often thinner that aluminium hubs, and so the usual length of
the spoke's elbowed section is not right; and the edge of the spoke hole
where the spoke bears is harder, and not always chamfered - these two lead
to nicks (and subsequent breakage) at the elbow.

Place a spoke through the flange so that the head is flush, and check how
much of the elbowed portion is exposed. If it's more than a millimeter, the
flange is to thin. If you cannot get the right spokes, an expedient
solution is to put small washers under the spoke heads. Brass would be a
good choice for these.

If the spokes have the correct length of elbowed section, check that the
spoke holes are chamfered; if they are not, careful use of a dremel tool
with a pointed grinding stone is the answer. You could use a proper
countersink or centre-drill, but it may well not last for 36 holes.

On Mon, 12 Dec 2005 12:09:22 +0100, Dieter Britz
wrote:

I have an old Torpedo back hub, probably about 30-40 years old,
the good kind that are indestructable (well, almost). It works
well but it has one problem: it eats spokes. I crack one about
once a fortnight. I have had such a hub before, and I wonder what
does this? With the last spoke, the head broke off, leaving the
elbow intact, whereas the one before it broke off at the elbow.

What does this, and is there anything I can do about it?

This is one of the classic failure modes of spokes that have not been
stress-relieved after installation in my experience, but there's also
the possibility that the holes in the flange have become worn so that
the spoke head and elbow are not correctly supported. If the holes
are not in bad shape then try stress-relieving the spokes.

see http://sheldonbrown.com/wheelbuild.html#seating
--
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In article , says...


I have an old Torpedo back hub, probably about 30-40 years old,
the good kind that are indestructable (well, almost). It works
well but it has one problem: it eats spokes. I crack one about
once a fortnight. I have had such a hub before, and I wonder what
does this? With the last spoke, the head broke off, leaving the
elbow intact, whereas the one before it broke off at the elbow.

What does this, and is there anything I can do about it?

It probably means the hole is not supporing the spoke properly. In Jobst
book he mentions bending the nipple end of the spoke so that the elbow is
better supported. Basically you straighten the bend a bit.
------------
Alex

Dieter Britz wrote:
I have an old Torpedo back hub, probably about 30-40 years old,
the good kind that are indestructable (well, almost). It works
well but it has one problem: it eats spokes. I crack one about
once a fortnight. I have had such a hub before, and I wonder what
does this? With the last spoke, the head broke off, leaving the
elbow intact, whereas the one before it broke off at the elbow.

What does this, and is there anything I can do about it?

what brand spokes are you using? quality makes a difference.