Re: [CR]High Flange/mid flange/low flange

(Example: Racing:Wayne Stetina)

Date: Thu, 13 Sep 2007 14:34:04 -0700 (PDT)
From: "Tom Dalton" <tom_s_dalton@yahoo.com>
Subject: Re: [CR]High Flange/mid flange/low flange
To: Steve Maas <bikestuff@nonlintec.com>, Classic Rendezvous <classicrendezvous@bikelist.org>
In-Reply-To: <46E97FC6.8060905@nonlintec.com>


Steve Maas <bikestuff@nonlintec.com> wrote: Sorry, it is more than a few tenths. I just ran two cases with Spocalc, which show about 5mm difference out of ~295 for Campagnolo high and low flange dimensions. This is still well below 2% though--it's hard to see that as significant for much of anything.

I say:

Five mm is a mile when you're building a wheel, which one knows if one builds wheels on a regular basis. There's a reason spokes come in one mm increments. I agree that the the mechanical influence of +/- 2% is likely insignificant, in and of itself. I never said otherwise, but the fact is, we're not talking about the "same" spoke lengths. If you're going to be rigorous, do so consistently.

Steve Maas wrote:

Frankly, I'd rather see the value of high-flange hubs in their elegance, and resist the urge always to read functional benefits into things that were not developed for functional reasons.

I say:

Do you really believe that the different hub sizes were developed for no reason other than visual appeal? That seems unlikely to me. Don't get me wrong, I too am unconvinced that there is a substantial mechanical difference, but wouldn't you think that varying flange sizes were at least an attempt to change something mechanically? In other words, there may be no actual benefit to "read in" but historically there may have been some beliefs that led to the different sizes, and those historical beliefs might be of interest.

As I said before, the primary difference between big hubs and little hubs, especially from the CR perspective, is the look. What's right for one era may be wrong for another. Actually, it was you who said that the benefit of high flange is that they look cool. That's a general opinion that you hold, which is fine, but it's perhaps more relevant that certain bikes are more "correct" with certain hubs. Either way, I agree that the mechanical diffs between flange sizes are near-zero for most applications, and that a lot of BS, folklore, and technical half-truth swirls around the supposed mechanical differences. Still, you said you've, "heard of no credible, significant technical advantage, " so I tried to present two actual geometric differences that MIGHT have a mechanical influence. It seems that you are intent on dismissing them as nonexistant, when they do, in fact, exist.

Steve Maas wrote:

The idea that you get more "angulation," to use your term ....

I say:

NOT my term. There is a reason that I said "I have no idea where I picked up the silly term "angulation," and I think it bears explanation," and that was to keep people like you from nitpicking my technically informal post.

Steve Maas wrote:

... is true only if the wheel is radially spoked. The idea that you get a greater spoke angle, for conventional tangential spoking, is a common misconception. Take a look at the geometry again--if the spoke comes off the hub approximately tangentially, there is no difference in angle compared to a low-flange hub. The length is also virtually identical (i.e., within a couple tenths of a mm). So, no difference in lateral strength.

We've already established that you are wrong about the length, and without proof I can't accept that you are correct about the spoke angle being identical. As with the length, there may be little influence on the structure, but the geometic differences are there. You just need to look at a wheel, and you can spare yourself some trig. Did I say these differences could be felt on the road, or would make one wheel more durable or anything like that? No, I was just trying to provide some explanation to a matter that you had not had explained to you to your satisfaction. Just trying to help. Notice that I said, " They may not meet your standards for significance, or even credibility." That's because I anticipated that you might recognize that the geometric differences I was pointing to, while present, did not amount to significant differences and did not provide credible explanation of any practical benefit to a particular flange size. What I didn't anticipate is that you would say that the geometric differences don't exist. That's a new one. They may be small and insignificant and not provide explanation of a practical mechanical difference, but it's odd to say they aren't there.

Steve Maas wrote:

This is all well covered in Brandt's book, by the way.

I say:

ALMOST NOTHING is well covered in Brandt's book. That book is a joke. One need look no further than his suggestion that wheels be wound up to the point of instability and then backed off half a turn. Then there is the absurd suggestion that spoke threads should be greased! WTF? It makes me seriously question if he's EVER built a wheel. But whatever, there's no arguing with engineers backed up by misapplications of theory. That guy is full of hairbrained ideas supported by so-called engineering that fly in the face of practical experience.

Steve Maas wrote:

I'd be interested in hearing how the location of the spoke cross has any effect on anything. Preferably with hard technical reasoning or data, not hand-waving arguments.

I say:

You've got the wrong guy, and the wrong forum, for rigorous explanations.

Steve Maas wrote:

I think radial spoking is indeed a bad idea, not just because hubs are not made for it. It's a bad idea because such a wheel can't support torque, and any unbalanced circumferential forces put a theoretically infinite tension on the spoke. (I know the standard argument: at least in front wheels, braking torque is balanced, which it is approximately. But when the force multiplication, that good ol' 1/cos(90) factor, is so high, this argument loses a lot.) This is an example of one of my favorite remarks: there are obvious bad ways to do things and nonobvious good ways. Tangential spoking is a nonobvious good way; radial is an obvious bad way. I see no reason to use something that has such clear flaws and no compensating benefits, at least beyond the "Bicyling Magazine" level of reasoning.

I say:

The Bicycling Magazine level of reasoning is no reasoning. That rag is staffed by poseurs and idiots. While I think on-the-road experience trumps engineering theory in many instances, those guys haven't a shred of either. Please don't insult my reasoning by likening it to that rag.

Look, you point out that there is no practical difference between large and small hubs and that's all I need. I agree. And if after what I said about geometry you have still not seen a technical explanation of why one hub would be better or worse, I'm good with that. It's all borne out by experience; there's not much difference. Well, by the same token, I don't need to know that as things go to 1/0 you get a big, big number to know that raidal front wheels look really cool on the right bike, and perform just fine on training wheels, and on racing wheels. Theory may not support the use of radial, but practical experience shows that it works just fine on many wheels.

Tom Dalton Bethlehem, PA USA

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