Hi guys,
Read some loose claims on another site about how beneficial it was for a 3X wheel to have the heads-in spoke go under the heads-out spoke at the last crossing. It didn't sound altogether credible. but it got me thinking - what good does the (lateral?) spoke crossing actually do?
I know from own experience that a wheel w/o this lateral cross may generate vibrating sounds if the spoke tension isn't quite as it should, but apart from that?
One casual analysis would give that you're preloading two flexible elements against each other, which AFAIK rarely is seen as good engineering.
Some further thought and you get the idea that maybe the lateral cross does something good by sort-of compensating between the differences in brace angle between outbound and inbound spoke. W/o the lateral cross the outbound spoke would be anchored a full hub flange thickness further out than the inbound. Assuming equal tension the lateral cross creates virtual anchor points that's only a half spoke diameter away from symmetry for both inbound and outbound spokes.
Then there's the question of torsion transfer interaction. If you have a rear wheel laced with pulling spokes inbound then torque transfer would reduce tension on the "pushing" spoke, causing the beneficial offset created by the lateral cross to be reduced as well.
A rear laced pulling outbound OTOH would instead increase tension in the "pushing" spoke during torque transfer conditions.
Ignoring the added complexites of torque transfer for awhile and simply looking at a wheel that's merely rolling along when being subjected to a sideways load, what happens then at the cross?
An inbound spoke passing through the load affected zone will lean against the outbound spoke at the outermost cross, but is the local sideways deflection of the rim sufficient for there to be any load transfer/tension increase to the outbound spoke that cross on the inside?
Or is it cross number dependent, with 1X, 2X offering too little separation between loaded spoke and supporting spoke för there to be any effect while 3X, 4X actually can offer some extra bracing?
Any thoughs?