[This article was originally published in The Moultoneer Number 33 (Nov/Dec 1992) as "ISO codes and the 17" wheels"]

The Obscure Swedish 17-incher

I assume other readers have already pointed out, apropos your article in the last issue (number 32, p 9), that the correct ISO designation for the Moulton 17" tyre is 32-369 and not 32-357, a fact which was indeed explained in your book (The Moulton Bicycle, p 130) a decade ago. [Ed - my apologies, I copied the error from the current CTC Member's Handbook!]

However, I found it an amusing coincidence that you should accidentally mention the 32-357 format since I was just about to write a short note to inform other Moultoneers of the existence of that 'obscure' little wheel - the Swedish 17-incher! As John S Allen explains in another article in Bike Tech (June 1983: "Odd Tire Sizes and Compatibilities"), traditional Swedish sizes are typically a few millimetres smaller in diameter than the nominally corresponding British sizes. This particular format (17" x 1-1/4" or 32-357) is still a common specification for children's bikes in Sweden, despite the recent influx of foreign wheel sizes via BMX types and 'Baby mointainbikes'. The 32-357 tyre is stocked in virtually every bicycle shop in this country and occasionally it can even be purchased in department stores and super markets, often as cheap as GBP2.00-4.00. It is difficult not to reflect on the fact that the standard, 'squashy' Moulton/Wolber multi-ribbed tyre retails for about five times as much in Sweden! Not surprisingly - now that the few remaining marques of the once prosperous Swedish rubber industry have quit making bicycle tyres altogether - all currently marketed 32-357s seem to be of Taiwanese origin and probably of a very basic quality.

Lightweight rims in the corresponding size (ISO 357-16 to 357-22) are more difficult to come by, unfortunately, but recently I managed to obtain a pair of very attractive looking Ambrosio rims (357-20/21) from a firm specialising in wheelchair building. I have also seen Alesa rims (on DBS juvenile bicycles) and a German brand that I don't recall the name of, all in aluminium.

A potential technical limitation with the Ambrosio rim is that it's only available drilled for 24 spokes (at least from my source). For my next project, a type 2 Moulton/DBS/Fram Stowaway, I am planning to build a pair of 357 wheels using a Sachs Penta-Sport 36-holed hub gear (skipping every third flange hole). By next spring I shall (hopefully) be able to tell how they perform, if anyone is interested.

The Moulton standard 17" rim, by the way, has an 18 mm inner width (ISO 369-18) and seems to be based on the old Weinmann 258 extrusion. The 258 model was incidentally the poorest performer in a research report on relative strength and rigidity of different rims, made by Chris Juden some years ago (Bike Tech, April 1984. "The Aluminium Rim: Design and Function").

Additional sources: John S Allen: "Understanding Tire Bicycle Sizes Sizes" (Bike Tech, February 1983) and Sutherland's Handbook pp12-27 and 12-30.