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

(Example: Events:Cirque du Cyclisme:2007)

Date: Thu, 13 Sep 2007 10:52:55 -0700
From: "Steve Maas" <bikestuff@nonlintec.com>
To: Tom Dalton <tom_s_dalton@yahoo.com>
References: <167796.754.qm@web55912.mail.re3.yahoo.com>
In-Reply-To: <167796.754.qm@web55912.mail.re3.yahoo.com>
cc: Classic Rendezvous <classicrendezvous@bikelist.org>
Subject: [CR]Re: High Flange/mid flange/low flange

The idea that you get more "angulation," to use your term ,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. This is all well covered in Brandt's book, by the way.

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 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.

Steve Maas Long Beach, California

Tom Dalton wrote:
> Steve Maas wrote:
>
> The main advantage is that the high-flange hubs are really cool looking.
> I have yet to hear of a credible, significant technical advantage. I
> have heard some claims that are incorrect. In particular, spoke length
> and angle are no different from short-flange hubs, unless radial spoking
> is used, which is a bad idea in any case.
> Steve,
>
> I agree with the first point, the main advantage of high flange is
> looks, especially from the perspective of most of us on this list. If
> high flange hubs end up on the wrong bike the looks are also the main
> drawback. This said, there are differences between high and low flange
> hubs. They may not meet your standards for significance, or even
> credibility, but the two that come to mind are as follows: 1) More spoke
> angulation, and 2) the final cross (on tangentally laced wheels) is
> closer to the rim. I have no idea where I picked up the silly term
> "angulation," and I think it bears explanation. What I'm refering to is
> the fact that the spokes on a high flange hub start at a closer radial
> distance from the rim, but approximatley the same lateral distance from
> the hub centerline when compared to low flange. As a result,
> the lateral component of spoke tension is higher, for a given tension
> along the spoke. This is why the Campy Record high-low actually makes
> some sense. It brings the obliquity of the left and right sides closer
> to even as compared to either a low or a high flange hub.
>
> On the second matter, for a given spoke pattern, the final cross is
> closer to the rim when you use a high flange hub. This leaves a shorter
> span of spoke between the last point at which the spoke gets support
> from the spoke it crosses, and where it meets the rim. I doubt this
> makes much difference, but there's a better chance that it will if the
> spokes are tied and soldered, as is typical with track wheels.
>
> You are incorrect that high and low flange wheels use the same spoke
> length except in cases where the spoking is radial. The correct spoke
> length typically differs, irrespective of cross pattern, but can be the
> same under specific conditions.
>
> As for radial spoking, I'd say it qualifies as a "bad idea" to about the
> extent that low or high flange hubs are better or worse than one
> another. It's just another example of a wheel configuration that has
> had it's significance seriously overblown. The only real issue with
> radial is that it overloads the hub flange and can lead to early flange
> failure. Obviously you need at least one tangental side on a rear
> wheel. A friend did the "experiment" of building a full radial rear,
> and while it was rideable, it had a lot of windup.
>
> Tom Dalton
> Bethlehem, PA USA
>
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