[CR] spoke tension, was Re: Campagnolo HiLo Lacing Pattern

Date: Mon, 17 May 2010 20:49:44 -0400
From: "Harvey Sachs" <hmsachs@verizon.net>
To: shop@cyclart.com, Classic Rendezvous <classicrendezvous@bikelist.org>
Subject: [CR] spoke tension, was Re: Campagnolo HiLo Lacing Pattern

Greg Reiche wrote: For rim braked wheels, alternate lacing patterns on front hubs don't make for any significant functional differences except flange durability. (...unless you are counting grams. The weight difference between 3x and 0x is about the weight of one spoke, FWIW.)

I don't know what was "traditional" on Hi-lo rear hubs. From a technical standpoint, it's complicated. Basically, you have tradeoffs (you always have tradeoffs!) depending on what attribute you want to optimize. You can consider functional attributes such as strength, stiffness, durability, and weight, or non-functional ones like aesthetics and spoke availability. No doubt there are others. On such a highly-refined assembly as a racing bicycle wheel, optimizing one attribute will, to a certain extent, take away from others. That extent may or may not be acceptable to you and your builder.

I recommend the lacing pattern that best balances power transmission, stiffness, and flange and spoke elbow life by minimizing spoke wind-up under torque. That is accomplished by having the spokes leave the hub flange as close to tangent as possible, or in other words, at a 90 degree angle. (Non-drive flanges on old Campy hubs transmit a negligible amount of torque, so from a functional standpoint, they can be laced whatever pattern you wish.) The number of crosses to use on the drive side depends on flange diameter and spoke count. The three most common drillings and their respective spoke angle are as follows:

36h 4x (gives a spoke angle of 92 deg.) 32h 3x (gives 80 deg. 32h 4x gives 102 deg, but spoke heads will overlap, so not recommended.) 28h 3x (gives 90 deg.)

You may manually enter and modify any combinations at the following link: http://www.appliedthought.com/danny/Spoke/SpokeCalculator.html +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Nice info, and I'd just add notes from the late Harlan Meyer, founder of Hi-E... Because of wheel dish, left side spokes have about half the tension of right hand spokes. Rather than using rather loose LH spokes and very tight drive-side spokes, Harlan offered wheels with half as many spokes on the left as the right. Or two thirds as many, like the famous 16/24, which went nicely on a 40 hole rim (if the spoke holes were symmetric). These actually seem to lace up nicely. Yes, radial is ok on the left. Ah! another Harlan Meyer trick, which I actually used once: Use 4x driving spokes, and 2x reaction spokes on the right side. anyone who notices will go nuts, and the only conceivable advantage is the minor weight saving from having a few shorter spokes. But, it has coolth and funk galore. Why did I sell that NOS 16/24 to another list member? Or did I?

harvey sachs
mcLean va.