Werehatrack wrote:
On 11 Jan 2006 03:06:55 -0800, "Nate Knutson"
wrote:

There are some really deeply discounted, nice 28 hole rims around. I'd
like to use some to build up some cheap wheels, but of course there
aren't many 28 hole hubs laying around at all.

[...] and there is no way that you can do it with equal
spoke tension. As a result, under load, the wheel is likely to
experience cyclic lateral deflection in the area where the greatest
spoke unloading occurs, which is in the area of road contact.

How can uneven spoke tension cause uneven rim deflection? If the spoke
is tight enough not to reach zero, then why would the stiffness be any
different to a wheel with evenly tensioned spokes?

2. Anyone built up any as rears, or as disc wheels? Anything exciting
happen if so?

Given the known need for unequal left/right tension, and the already
noted uneven tension within a side in the wheel under discussion, I
believe that this is a bad idea. It is likely that the wheel would be
difficult to get true and properly dished with adequate spoke tension
everywhere..

My experience with 24 spokes in a 36H hub was easy. Sure, there are
uneven tensions, but I don't see an issue with that in practice.
There's a range of tension in any tensioned spoked wheel. The loosest
spoke only has to be tight enough, then the tightest spoke is what it
is. The range in a strange wheel might be a bit larger, but other than
theoretically shorter rim life (due to the higher tension in the
tightest spoke) there's no functional down side I see. Am I missing
something?

3. Anyone have any insights about whether there would theoretically be
any problems with torsional strength using this lacing pattern as a
rear or disc wheel?

Braking forces are seldom at the magnitude of forward accelerations in
a low gear on a hill.

This is opposite my hunch, but I admit we might be coming at this from
different assumptions. I've always observed quicker rates of
deceleration than acceleration, but it's not been gauged. It's be nice
to make some measurements of accelerations/decelerations to find out.
For example, I can stop hard eough to raise the rear tire, but I can't
pedal hard enough to raise the front tire (unless I also jerk on the
bars).

[...T]he typical disc hub
has less flange offset than a rim-brake hub. In theory, this might
actually make the proposed rear wheel easier to attempt since the
left/right spoke tension imbalance is reduced,

Right, this is important to consider on any front disc wheel: no doubt
the front hub's disc-side flange is closer to center than a similar
non-disc brake hub's. But the rear hub's disc-side flange (on hubs I've
checked, anyway) has about the same offset as the non-disc version, so
for me it wouldn't normally be a consideration for the rear wheel.