<< Norris Lockley: There is another and separate aspect of spoke lacing a wheel and that concerns the side of the flange from which the spoke enters the wheel ie on which side of the flange should the spoke's head reside - externally or internally..in order to obtain the optimum traction...and..do wheels perform best when built in the symetrical or non-symetrical ie mirror/non-mirror pattern of spoke-lacing? I have my own views but would welcome those of other CR Listers, particularly as it appears that there are quite lot of wheelbuilders on the List>>
Norris,
I'll bite. I prefer to build rear wheels mirror-image, with the "pulling" spokes laced head-out. I have several reasons for this:
1. Head-out spokes run in a straighter line to the rim than head-in. There is no additional point of contact to the hub flange as with head-in spokes, so no chance of a stress riser near the elbow. 2. At the point where the spokes interlace, head-out spokes are on the outside. Pedaling torque tightens the head-out ("pulling") spokes and loosens the head-in spokes, which (in this configuration) pulls the drive-side spoke plane ever-so-slightly towards the wheel centerline. This lessens the chance of the derailleur cage hitting the spokes when in the lowest gear on the rear cogs (which gear applies the highest torque to the hub.) 3. Even though the percent of torque transmitted from the drive side of the rear hub to the non-drive is often minimal, especially with vintage small-barrel hubs, having mirror-image spoking reduces the overall side-to-side deformation of the rim, keeping it closer to the wheel centerline under high torque. This probably reduces both rim and spoke fatigue. 4. In the event of a low-gear overshift, the higher-stressed pulling spokes are protected from damage from the chain.
The only exceptions I make are when I'm re-using a hub with spoke holes that are significantly deformed by previous builds, in which case I stick with the pattern already imprinted. I will also lace to cover cosmetic damage on the flange from corrosion or fretting.
Realistically, most of these issues are unlikely to be significant except at the extremes of use, e.g. a heavy or strong rider, or an ultra-light wheelset, or a heavily-loaded tourer, or very high-mileage wheelset, or a frame with extremely close clearances. In other words, these are "one-percenter" issues, and statistically speaking, they can safely be disregarded as long as a wheel is otherwise well-designed and built. Then again, as one who has built a statistically significant number of wheels over my career, I think about that one percent, so I build them to my preference whenever possible.
Gre Reiche
CyclArt
Vista, CA USA