A quick trip to the Wheelmen site provided quite a bit of Iver Johnson serial number information. Bill Smith appears to have studied the firm and the bicycles at length and has built a serial number model chart, which he uses to project build dates for the bikes. While he has answered questions about dating individual bike he has not published an overall list as, in his words, he is constantly fine-tuning his model as more information comes in.
My observation has been that as far back as any Iver Johnson recorded serial numbers have been reported, it appears that the bicycles were numbered in a simple progressive arithmetic-sequencing pattern. If this is true then any bike’s build date can be projected by where it falls between two other known and dated bikes. Obviously the closer together those bikes are the more accurate the projection will be.
From the numbers that have been queried and responded to by Mr. Smith, it is relatively easy to build a model and to project where the major serial number breaks occur (i.e. 100,000 200,000 etc.) From the few data point we have it is a best practice to build the model against a curve based on the generally known characteristics of annual U.S. bike production and consumption until we reach the later years where Iver was definitely loosing ground.
In the Wheelman texts I scanned, the highest Iver serial number mentioned was 608722.
As I noted earlier and elsewhere, locating the earliest serialed Balloon Iver will give us a relatively clear reading of how many units were produced after 1933/34 and before 1942.
As Mr. Smith is loath to publish his model, I don’t want to step on any toes by suggesting we build a model here; but if the desire for a chart produces one it will just be a second model from which to draw references. So, in general, I still believe it would behoove us here to record numbers against bikes but it is also true that a quick, accurate and specific answer is probably available from the horse’s mouth.