Re: [Classicrendezvous] parallelograms

Date: Wed, 29 Nov 2000 09:11:08 -0500
From: Jerry Moos <>
To: stephen fredette <>
Subject: Re: [Classicrendezvous] parallelograms
References: <l03130301b64aa780596e@[]>

I think we discussed the SunTour design over a year ago and concluded that a similar-appearing design was used by several other manufacturers. While the Suntour parallelogram front and rear plate appeared "horizonal" when viewed from a distance, as opposed to "vertical" for the Campy NR, on closer inspection one could see that the top edge of the parallelogram also slanted backward toward the freewheel, i.e. the parallelogram plates lay not in a plane perpendicular to the ground, but in a plane oblique to the ground. The slant back toward the FW was the "Slant" in Slant Parallelogram, and the secret of SunTour's superior performance. It was also apparently the basis of the SunTour patent, as several manufacturers introduced a horizonal parallelogram, but with the parallelogram plates in a plane perpendicular to the ground, lacking the SunTour "slant". Such derailleurs included the Shimano Crane, some versions of the Simplex SLJ (the 6600, for example) and the Campy Rally. The Crane definitely came out well before the SunTour patent expired in 1984, and the others may have as well. When the new Campy road gruppos (C-Record, Victory, Triomphe) came out about 1986 or 1987, there still wasn't a slant parallelogram in the lot.


Jerry Moos

stephen fredette wrote:
> i'd like to thank everyone for their help
> about the long cage campagnolo derailleur.
> on a tangent to that, could someone tell
> me if the original rally uses the slant
> paralellogram (or is it double
> paralellogram) that suntour held the patent on
> for so many years. and if not, when campagnolo
> switched. this could help me date this
> derailleur. sorry for the idee fixe.
> yr obdt svt
> Stephen Fredette
> Hull, Massachusetts