Quoted message said:From: http://motoring.independent.co.uk/comment/story.jsp?story=635101
or: http://tinyurl.com/7mqdc
"The secret of the seemingly flimsy wire wheel is that all its spokes
are in tension. Electroplating steel spokes puts a compressive stress
into their surface, dangerously shortening their fatigue life. "
Where *do* these things start?
Quoted message said:"... No
self-respecting scrutineer at a race meet would allow a car with plated
wire wheels out on to the track, but people continued to demand them.
On the whole, it was one more reason why the wire-spoked wheel has
disappeared from modern cars."
Manure. Wire-spoked wheels vanished from the car market because they
were a royal pain in the neck, seldom worked well as tubeless units,
were much more expensive, and were *heavier* than conventional wheels
in automotive applications. Yes, there is still a fashion-driven
demand for them, but it's happily quite small, and is serviced by a
few specialty makers who demand princely sums for what are often
inferior products. (This same observation applies to a large portion
of the overall aftermarket wheels available, for that matter.)
Quoted message said:Is this similar to the anodizing problem -- I've never read that
anodizing introduces 'compressive stress'. If it is a separate
phenomenon, does the 'crazing/cracking' problem also occur with
chrome-plating?
First, the alleged "compressive stress" had no bearing on fatigue
failures. The surface polishing and chemical etching that precedes
the deposition portion of the plating process can be a problem, in
that it creates surface stress risers which hasten failure. (I recall
seeing this explicitly cited years ago, but I also seem to recall that
it was stated that the reason factory-supplied spoked wheels weren't
chromed had to do with the difficulty of making such a wheel durable
due to other issues...not the least of which was that the chrome
tended to peel from the spokes, leaving nasty sharp edges.)
Second, anodizing's effects do not introduce any stress, but they may
introduce stress *risers*; places where the metal-to-hydroxide
conversion process accentuates flaws in the material. Anodizing
effectively removes metal. In an application which has already been
engineered too slose to the limits of the material, the additional
loss of thickness due to the conversion may be critical, as is
apparently part of the problem with certain infamous Mavic rims.
Quoted message said:Many steel bikes have chromed elements of the frame -- is this A Bad
Idea fatigue-wise?
No.
Quoted message said:Chrome-plated areas are usually situated at the
areas that most often fail: dropoouts, fork crown, lugs etc.
It's only an issue in that a higher clamping force may be required in
order to keep a wheel from slipping in the dropouts when chorome
plating is present. Chroming has no significant drawbacks for a frame
otherwise.
--
Typoes are a feature, not a bug.
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