Re: [CR] Strong, Longlived Wheels

(Example: Bike Shops)

Content-Class: urn:content-classes:message
Date: Wed, 26 Aug 2009 18:01:44 -0500
Thread-Topic: Re: [CR] Strong, Longlived Wheels
Thread-Index: AcomoS56tYowj4v7RJyFgx0wsPKuiQ==
From: "John Hurley" <JHurley@jdabrams.com>
To: <classicrendezvous@bikelist.org>
Subject: Re: [CR] Strong, Longlived Wheels


I'll risk stirring the pot a little.

Jerry Moos values uniform spoke tension. If I understood him correctly, Don Gillies thinks this was over-simplification because uneven spoke tension is sometimes unavoidable in order to true the wheel. Don favors heavier spokes, and admits uniform tension is important, if it can be achieved, but high spoke tension is the key for him. Chuck Hoefer added that when it comes to potholes, spoke gauge doesn't matter compared with tire selection.

I think, as in the case of the seven blind men who went to see the elephant, it is easy to think the other guy is wrong, when really we are talking about different aspects of a thing. I guess the best bicycle wheel is the one most suited to its purpose and the one that most successfully balances all the requirements of strength, weight, cost and durability. All the elements have to work well together as well as individually.

The job of the spokes is to transfer forces back and forth between the hub and the rim. Uniform spoke tension is important here, because a loose spoke is shuffling it's work off onto the other spokes and the rim. I believe Jerry was also referring to uniformity of left-side versus right-side spokes. I don't think anyone would disagree that even spoke tension is important.

High spoke tension is desirable, I think, to make sure every spoke is in play and immediately responds to the load. It also may help with fatigue by reducing the amplitude of cyclic loading. I wonder, too, if higher spoke tension and even spoke tension sort of go together. I mean, maybe higher spoke tension makes it harder for a loose spoke to hide out. Too much tension, on the other hand, is going to overload the end connections, including hub and rim holes.

Lighter spokes are going to be more stretchy, heavier ones more rigid. Rigidity is good up to a point, but heavier spokes add weight. People figured out long ago that spokes tend to fail at the end connections, and elasticity wasn't a controlling factor, hence butted spokes. Isn't the optimal number and gauge of the spokes going to be a function of the rim section? The deeper and heavier the section, the fewer spokes needed, and the reverse? More is better when it comes to spokes because they keep the rim round under load and just divide the forces into more and smaller increments, but I suppose the game has always been about finding how many you could eliminate and still keep your face off the pavement.

The tire, it seems to me, is a variable. The tire is a buffer between the road and the rim, and different tires at different pressures will do better or worse, but this doesn't really tell you anything about the design of the wheel. I mean, shouldn't the question should be which wheel performs better given the same tire? When it comes to handling potholes, I would think the main factor would be rim cross-section.

Above all, it seems to me the weight of the rider and any baggage must be considered. What is plenty strong and durable for a 115-lb girl is probably totally inadequate for big heavy guy. Is there a built-in penalty here for lighter cyclists? Production wheels have to be built with someone in mind, and I doubt it is the lightweight individual.

With all these variables in play, it is no wonder that theories abound, some of which border on superstition.

John Hurley
Austin, Texas, USA