"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?
"... 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.)
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.
Many steel bikes have chromed elements of the frame -- is this A Bad>Idea fatigue-wise?
No.
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. Some gardening required to reply via email. Words processed in a facility that contains nuts.
"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. ">
In article <1115152326.ee9b6b4d0a5cc2dec9fe93fa37bff09b@teranews>, N0SPAMdiabloscott@terra.es says...> >>"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. "> > isn't the idea of shot peening and the like to put the surface layers into compression (as well as work hardening etc.) to improve fatigue life?
"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. 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."
There was the whole hydrogen embrittlement thing too. Much bigger issue.
Ron
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?>
Many steel bikes have chromed elements of the frame -- is this A Bad>Idea fatigue-wise? Chrome-plated areas are usually situated at the>areas that most often fail: dropoouts, fork crown, lugs etc.>
