[CR]Assymetrical lacings

(Example: Framebuilding:Tubing)

Date: Fri, 09 Sep 2005 20:51:44 -0400
From: "Harvey M Sachs" <sachshm@cox.net>
To: neill_currie@comcast.net, Classic Rendezvous <classicrendezvous@bikelist.org>
Subject: [CR]Assymetrical lacings

Neill Currie wrote:

Well, I guess it may have been, almost, beaten to death recently as to whether one can feel the difference in ride quality between 4 cross and 3 cross, or low versus high flange lacings. However, there's one question I have, and I am not sufficient of a mathematician/physicist to answer it for myself. To (possibly??) compensate for the difference between spoke tensions on rear wheels with (lots/some) dish, some people advocate lacing the drive side 4 cross and the non-drive, say, 2 cross. The question is: does this really provide a measurable compensation for the spoke tensions typically experienced versus the same wheel laced 3 cross each side, and if so, by how much does it compensate?? ++++++++++++++

For a dished wheel that has the same number of spokes on each side, the side with the shallower included angle (rim-hub-rim) will have more tension on the average spoke. Usually the right side is much shallower, and thus more tensioned. Maybe that's why the drive side spokes broke more often? It wasn't just the orneriness of breaking the spokes that required pulling the (tourist) FW to change, was it?

In the 5-speed and 6-speed world, we always thought it was about twice as high, but this can be solved with simple trig.* Now, I could be wrong, but i think it is the hub-rim-hub angle that matters, essentially independent of the actual spoke length. So, if you want to equalize tension, you use (in this case) Harlan Meyer's Hi-E approach: twice as many spokes on one side as the other. I'm looking now at eye candy: an NOS Hi-E Hi-Lo hub that a list member essentially gave me (Joe B-Z? how short the memory?). It's drilled 16 (low)/32 high, so it will lace up with a perfectly ordinary 48 hole rim - IF you stocked up on these when they were popular for tandems, and IF you don't go nuts trying to remember that the spokes will lace the rim as left-right-right-left-right-right-left. Sort of like my Junior ROTC unit trying to do a dress parade the first week of school? :-)

FWIW, I think I remember seeing a 14/28 spoke Hi-E wheel. Got any spare rims drilled 42 hole on center?

harvey sachs mcLean va *and thus, as my math prof would say, is best left as an exercise for the student (It will be on the test).