Mark,
A little thread drift here...
The original Michelin Elan tires were 700x19c or 20c (and 27x3/4"). They were developed in conjunction with Mavic to mount on their Module-E rims (E for Elan). They had beads designed to fit into the hooked lips of the Module-E rims.
This was a serious attempt to provide sewup like performance in a clincher style rim and tire combination. The Module-E rims were narrower than most alloy clincher rims of that era, about the same 20mm width as sewup rims. This coupled with the 700c size wheels allowed a cyclist to switch from clinchers to sewups and back without having to adjust their brakes.
Before that, several Italian companies sold some not so cheap tires made with cheap sewup casings with wire beads to mount on clincher rims. The sidewalls blew out on the first few rides!
The first generation Elan tires were TERRIBLE! They had casings made of a thin nylon hairnet like material with very thick gum rubber sidewalls. They were rated at 90 psi which you needed to run to prevent snake bites and rim damage from bottoming out.
We stopped selling Elans after a few months because we had numerous Elan tires blow out on bikes sitting in our showroom plus too many customer complaints. We even had some blow up when first inflating them.
The problem was the nylon hairnet casing was too thin. Elans frequently blew out where the tread met the sidewall.
They didn't ride very well either because of the small cross section plus the thick gum rubber in the sidewalls.
Pictured in the link below is a set of 700x25c Elans that came on a bike I bought last year. They're wall hangers now as the casings are starting to split where the tread meets the sidewalls!
>http://tinyurl.com/yl62lf3<
Within 6 months, (early 1976) Wolber brought out their W20 tires which had a 20mm cross section. They offered good performance. W20s had a strong lightweight casing made of "long staple" Egyptian cotton with very thin rubber on the sidewalls (we imported some Wolber tires).
The W20s in the link below came on a set of 700c Module-E wheels that I recently bought. They're still ridable - almost!
>http://tinyurl.com/ybo56hb<
Rigida introduced their 1320 rims around that time too. They were the first rims that I ever saw where the side walls were made so thin that they wore through from normal braking!
A little later Super Champion brought out their Gentleman rims which were a slight improvement over the Module-E rims and head and shoulder better than the 1320 rims.
After that most of the tire and rim makers joined the fray with Specialized marketing some of the better tires of that era.
Chas. Colerich Oakland, CA USA
Mark Stonich wrote:
> At 3/21/2010 07:20 PM -0700, David Snyder wrote:
>> A narrow rim necessitates a bit higher pressure to prevent pinch flats
>> with the same tire.
>
> Don't you mean a wider rim? When the 25mm Michelin Elans 1st came out,
> "snakebite" flats were common when they were mounted on the Super
> Champion Mod 58s etc. The introduction of narrow rims like the Rigida
> 1320 cured the problem.
>
> Mark Stonich;
> BikeSmith Design & Fabrication
> 5349 Elliot Ave S. Minneapolis, Minnesota 55417 USA