Spoke line correction, elbows, hub bedding, stress relief: will photos show all?



I'm not sure where to put a reply in this great thread, so I've started
a new one... ;-)

If a person were to build a wheel from new components, how could s/he
answer some of the questions this thread has highlighted?

For example, I think I read jim beam saying 95 degrees is about right
for a spoke elbow in a wheel. Could a person show this to be the case
(or not) by photographing a wheel at some stage during assembly, or by
showing a hub with (say) dowel pins in each spoke hole to reveal spoke
holes whose axes are all parallel (or form a cone), etc.?

For another example, I think I remember Jobst Brandt saying the holes
in the hub flanges take up the shape of the spoke as a result of normal
spoke tension, so no significant additional hub hole forming (bedding
in) takes place as a result of squeezing spokes. Could someone building
a wheel with new components take a series of pictures of a hub hole
deforming as spoke tension is slowly increased?

For a third example, I seem to recall Jobst also saying spoke elbows
take up a different angle after tensioning (in a wheel) than they had
when new. Could someone photograph a spoke before and after installing
it in a wheel to show this to be the case or not?

What, specifically, could a careful person do while building a wheel
and what kind of pictures could s/he take to illuminate some of these
questions?
 
On 8 Jan 2005 08:30:51 -0800, [email protected] wrote:

>I'm not sure where to put a reply in this great thread, so I've started
>a new one... ;-)
>
>If a person were to build a wheel from new components, how could s/he
>answer some of the questions this thread has highlighted?
>
>For example, I think I read jim beam saying 95 degrees is about right
>for a spoke elbow in a wheel. Could a person show this to be the case
>(or not) by photographing a wheel at some stage during assembly, or by
>showing a hub with (say) dowel pins in each spoke hole to reveal spoke
>holes whose axes are all parallel (or form a cone), etc.?
>
>For another example, I think I remember Jobst Brandt saying the holes
>in the hub flanges take up the shape of the spoke as a result of normal
>spoke tension, so no significant additional hub hole forming (bedding
>in) takes place as a result of squeezing spokes. Could someone building
>a wheel with new components take a series of pictures of a hub hole
>deforming as spoke tension is slowly increased?
>
>For a third example, I seem to recall Jobst also saying spoke elbows
>take up a different angle after tensioning (in a wheel) than they had
>when new. Could someone photograph a spoke before and after installing
>it in a wheel to show this to be the case or not?
>
>What, specifically, could a careful person do while building a wheel
>and what kind of pictures could s/he take to illuminate some of these
>questions?


Dear Dianne,

You might use two duplicate hubs and an extra spokes to show
changes without dowels.

Lay a new hub flat on a table, holding it down firmly. Put a
new spoke into it so that it sticks out at 90 degrees (as if
for a radial lacing), hang a small weight on the end.

Take a picture from the side or else record where the end of
the spoke ends up. You'll need marks and a repeatable setup.

(This is where I measure twice and then cut two or three
times before getting a new board or giving up, but I suspect
that you're rather better at this kind of thing.)

Mark the hole that you used.

Do it again with the extra spoke, the one that you're really
going to use.

Do it all over again with the same spokes on the extra hub
that you're not going to use.

Now you know how a control spoke and a spoke that you're
going to use sit in a control hub and the hub that you're
going to use.

Build the wheel to whatever point interests you (tension,
tension and alignment, tension and alignment and spoke
squeezing).

Take it apart.

(Sorry, but I think that you have to take it completely
apart. If you're doing a series of checks, you have to mark
it all and lay things aside in the right order so that it
gets put back together with the same spokes in the same
holes.)

Stick the used spoke in the unused extra hub, hang the
weight on the end, and see if anything's changed. If the
used spoke droops differently, then it was bent at the
elbow. Since you're measuring the far end of the spoke, even
tiny differences should show up.

Now stick the unused extra spoke into the used hub and hang
the weight on it. If the unused extra spoke droops
differently or wants to move to something other than a
radial lacing angle, then the hub hole has changed.

I think that this would show when and how much anything
deforms at the gross level, but not anything microscopic
like the grain of the metal or elongation of the spoke. But
maybe if you measured lengths you'd find something really
curious, such as the spokes ending up a millimeter longer?

Carl Fogel
 
A

Alex Rodriguez

Guest
In article <[email protected]>,
[email protected] says...
>I'm not sure where to put a reply in this great thread, so I've started
>a new one... ;-)
>If a person were to build a wheel from new components, how could s/he
>answer some of the questions this thread has highlighted?
>For example, I think I read jim beam saying 95 degrees is about right
>for a spoke elbow in a wheel. Could a person show this to be the case
>(or not) by photographing a wheel at some stage during assembly, or by
>showing a hub with (say) dowel pins in each spoke hole to reveal spoke
>holes whose axes are all parallel (or form a cone), etc.?
>For another example, I think I remember Jobst Brandt saying the holes
>in the hub flanges take up the shape of the spoke as a result of normal
>spoke tension, so no significant additional hub hole forming (bedding
>in) takes place as a result of squeezing spokes. Could someone building
>a wheel with new components take a series of pictures of a hub hole
>deforming as spoke tension is slowly increased?


This would be a pain to do because you won't see the deformation unless
you remove the spoke. I also don't see what knowledge there is to gain
by this series of photos. You can easily see the deformation when you
unspoke a previously built hub.

>For a third example, I seem to recall Jobst also saying spoke elbows
>take up a different angle after tensioning (in a wheel) than they had
>when new. Could someone photograph a spoke before and after installing
>it in a wheel to show this to be the case or not?


In Jobst' book there are illustrations of this. You can also see this yourself
by looking at a used spoke and comparing it to a new spoke.

>What, specifically, could a careful person do while building a wheel
>and what kind of pictures could s/he take to illuminate some of these
>questions?


A copy of Jobst' book would answer most of your questions. You could also
check with your LBS. I'm sure they could show you a used hub that is not
built up as well as some used spokes.
------------
Alex