[CR] Re: [Classicrendezvous] parallelograms

Example: Framebuilders:Alberto Masi

Date: Fri, 1 Dec 2000 11:00:58 -0800 (PST)
From: Tom Dalton <tom_s_dalton@yahoo.com>
To: Jerry Moos <moos@penn.com>
Cc: classicrendezvous@bikelist.org
Subject: [CR] Re: [Classicrendezvous] parallelograms

Jerry, The first post-SR ders. were pretty much face-lifts on existing designs (NR/SR). The first true attempts at a proper indexing derailleur were the Chorus and then the Croce. The Chorus featured the slant parallelogram and could actually be set to either of two inclines. There was no pivoting action (a la Shimano) at the mounting bolt. The Croce did pivot at the mounting bolt, but was articulted in a rather ridiculous fashion using a pushrod driven by the cable housing. I think Campy did it this way so that the der. would track like a Shimano but not be a Shimano copy.

The first indexing derailleur (at least the first one that was a commercial success) was the 6 spd Dura Ace (RD-7400). Interestingly, this was the first Shimano derailleur to adopt Suntour's slant. The comnbination of the slant and the pivoting body made Shimano's indexing superior to Suntour's and Campy's attempts to follow. Eventually Suntour got out of the component biz and Campy started making Shimano copies. Since they started copying Shimano's derailleur design, Campys have been consistently almost as good as Shimano. But hey, that's just my opinion...

Tom Dalton

--- Jerry Moos wrote:

> I think we discussed the SunTour design over a year

\r?\n> ago and concluded

\r?\n> that a similar-appearing design was used by several

\r?\n> other

\r?\n> manufacturers. While the Suntour parallelogram

\r?\n> front and rear plate

\r?\n> appeared "horizonal" when viewed from a distance, as

\r?\n> opposed to

\r?\n> "vertical" for the Campy NR, on closer inspection

\r?\n> one could see that the

\r?\n> top edge of the parallelogram also slanted backward

\r?\n> toward the

\r?\n> freewheel, i.e. the parallelogram plates lay not in

\r?\n> a plane

\r?\n> perpendicular to the ground, but in a plane oblique

\r?\n> to the ground. The

\r?\n> slant back toward the FW was the "Slant" in Slant

\r?\n> Parallelogram, and the

\r?\n> secret of SunTour's superior performance. It was

\r?\n> also apparently the

\r?\n> basis of the SunTour patent, as several

\r?\n> manufacturers introduced a

\r?\n> horizonal parallelogram, but with the parallelogram

\r?\n> plates in a plane

\r?\n> perpendicular to the ground, lacking the SunTour

\r?\n> "slant". Such

\r?\n> derailleurs included the Shimano Crane, some

\r?\n> versions of the Simplex SLJ

\r?\n> (the 6600, for example) and the Campy Rally. The

\r?\n> Crane definitely came

\r?\n> out well before the SunTour patent expired in 1984,

\r?\n> and the others may

\r?\n> have as well. When the new Campy road gruppos

\r?\n> (C-Record, Victory,

\r?\n> Triomphe) came out about 1986 or 1987, there still

\r?\n> wasn't a slant

\r?\n> parallelogram in the lot.


\r?\n> Regards,


\r?\n> Jerry Moos


\r?\n> stephen fredette wrote:


\r?\n> > i'd like to thank everyone for their help

\r?\n> > about the long cage campagnolo derailleur.

\r?\n> > on a tangent to that, could someone tell

\r?\n> > me if the original rally uses the slant

\r?\n> > paralellogram (or is it double

\r?\n> > paralellogram) that suntour held the patent on

\r?\n> > for so many years. and if not, when campagnolo

\r?\n> > switched. this could help me date this

\r?\n> > derailleur. sorry for the idee fixe.

\r?\n> > yr obdt svt

\r?\n> > Stephen Fredette

\r?\n> > Hull, Massachusetts