Originally Posted by
dddd
I have trouble embracing the idea that a manufacturer would want to use a rolling process for putting threads on a steer tube, given that the tolerances of 1" tubing are what they are(?), and with the threads and wall thickness being so shallow and thin. A variation of thread depth might result from the combined tolerances of wall thickness and roundness unless the tubing was of a very high-tolerance that would be expected to increase cost.
I could almost imagine that a needed mandrel might flex enough to require something akin to a single-point rolling operation, which I've never heard of, since a substantial length of threading is often applied, or more likely that the ID of the tube might end up out of spec (oversized) from the rolling operation.
I can't recall having ever seen a steerer that appeared to have rolled threads, but have noticed that new ones always look to have cut threads.
And, if any maker did use rolled threads on a steerer, you would think that they would tout this in their marketing, as it would likely have been costly to accomplish. But then, they would have to be able to say that they also rolled or formed the flat or groove, so as to be seen as consistent in whatever argument for rolled threads that they put forth.
So, in the well-remembered words of my enthusiastic high school trigonometry instructor Mr. Kutnohorsky (or "Cut", as the hipsters referred to him), when referring to the use of any less-than-simplest approach to solving trig problems, "It's a nightmare".
Cheap department store bikes used them, and Steve at Bilenky seems to have some nicer ones - which you didn't believe. I have seen cheap steerers that are barely round and looked like some process far from a lathe was involved.
I'm coming into this "conflict" late, but you should consider that there is probably a good reason a lot of people think that some threads are rolled. It isn't because they all took tours of bike factories, or had rolling machines at the bike shop. Most shop employees wouldn't even consider that something threaded get that way in a process different than the frame prep tools they are familiar with. So if the rolled thread thing is a complete fabrication, who came up with it and why?
I believe that rolled threads were likely at some point because of what little I know about industrial processes prior to CNC - stamping and forming were much preferred for most of the 20th century because they tended to strengthen cheap steel and was much easier on the tooling. Now we think of everything being cut out of blocks of billet, but in decades past those types of machine operations were avoided.