RE: [CR]Twisted spokes

(Example: Framebuilders:Jack Taylor)

From: "Mark Bulgier" <mark@bulgier.net>
To: classicrendezvous@bikelist.org
Subject: RE: [CR]Twisted spokes
Date: Tue, 16 Jul 2002 18:10:56 -0700


Several people posted to the effect that wheels with twisted spokes are stronger and/or stiffer. Just so readers won't be left with the impression that this is universally accepted, I'd like to point out that at least some experts feel that is utterly untrue - that it can't increase the strength or stiffness at all.

I believe the main effect, pretty much the only effect it has, is to ensure that one spoke breaking will effectively take out two spokes and make the wheel unrideable - where a similar untwisted wheel would have been rideable with a spoke broken. (On the rear wheel, twisting spokes makes the wheel considerably more flexible in the "windup" direction, but wind-up is quite unimportant anyway, so this isn't a serious problem)

The claims are especially unrealistic with respect to stiffness, because even if the spoking pattern could double the stiffness (an absurd suggestion no one is claiming), no one would notice. That's because all wheels are, for all practical purposes, infinitely stiff vertically already. Any vertical give they have is masked by the give in the tires, which is probably a hundred times greater. Vertical stiffness of wheels can be measured in the lab, but the differences are beyond the range of human perception. By the way, tied-and-soldered was not found to have any effect on stiffness, in the two studies I saw using precision machinist's measuring devices. Anecdotal reports of "harshness" are easily explained by the power of suggestion and other psychological factors.

Remember we're not comparing the world's stiffest and most flexible wheels - we're comparing two wheels with identical rims, and the same number and type of spokes - just a little longer, and twisted, on one of the wheels. I'll be convinced when test riders correctly report which wheel is stiffer in a double-blind test. Similar tests have been done with other, larger differences than we're talking about here, and the riders couldn't tell any more accurately than flipping a coin.

Sorry if this takes any of the romance out of wheels for anyone.

Classic content: tied and soldered, if done well, is extremely cool whether it makes the wheel any faster or not. It's got mojo that speaks to my romantic side. It also restrains a broken spoke to allow the rider to finish the ride without being impaled or having it slap against the frame etc, a plus to pro riders, that offsets the extra labor to replace the broken spoke. The rest of us can get off and take the spoke out or bend it around, making T&S a lot less of an advantage. It's hard to imagine a classic lightweight where twisted spokes would be appropriate though.

Mark Bulgier
Seattle, Wa
USA