Help me understand what changed when SunTour's slant parallelogram patent expired...
#1
Senior Member
Thread Starter
Join Date: Aug 2007
Location: Evanston, IL
Posts: 5,833
Bikes: many
Mentioned: 61 Post(s)
Tagged: 0 Thread(s)
Quoted: 1421 Post(s)
Liked 1,344 Times
in
737 Posts
Help me understand what changed when SunTour's slant parallelogram patent expired...
I'm trying to understand how rear derailleur movement of the SunTour slant parallelogram works and was different than its contemporary competition, particular from Shimano. Consider these two Shimano 600EX versions:
Both seem to have the cage paralleolgram angled from "northwest" to "southeast", not unlike the SunTour Cyclone, and unlike the Campy NR (where the cage runs "north" to "south"). The Arabesque derailleur dates from well before the expiration of SunTour's patent. I think the later 600EX dates from after the expiration of that patent.
I'm clearly misunderstanding something about the way the cage moves between the earlier Arabesque and later 600EX derailleurs. Can someone explain this too me? Pointers to pictures or graphics demonstrating the slant parallelogram mechanism would be great. I found this YouTube video, but the description implies that the Arabesque derailleur has a slant parallelogram design.
Thx,
Skip
- Arabesque
- Fourth Gen (I think, just before SIS)
Both seem to have the cage paralleolgram angled from "northwest" to "southeast", not unlike the SunTour Cyclone, and unlike the Campy NR (where the cage runs "north" to "south"). The Arabesque derailleur dates from well before the expiration of SunTour's patent. I think the later 600EX dates from after the expiration of that patent.
I'm clearly misunderstanding something about the way the cage moves between the earlier Arabesque and later 600EX derailleurs. Can someone explain this too me? Pointers to pictures or graphics demonstrating the slant parallelogram mechanism would be great. I found this YouTube video, but the description implies that the Arabesque derailleur has a slant parallelogram design.
Thx,
Skip
#2
Ride, Wrench, Swap, Race
Join Date: Jan 2010
Location: Northern California
Posts: 9,167
Bikes: Cheltenham-Pedersen racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.
Mentioned: 132 Post(s)
Tagged: 0 Thread(s)
Quoted: 1552 Post(s)
Liked 1,268 Times
in
843 Posts
The "dogleg" of the Arabesque and certain of the later Simplex derailers doesn't use the slanted parallelogram, and so wouldn't violate any patents.
The difference with the slant parallelogram was that the parallelogram pivots were off-axis from being perpendicular to the axle, so that the shifting motion moved the cage further away from the axle as the larger sprockets were engaged.
Shimano spent years developing SIS, knowing full well when the patent expired. Thus, when the first SIS gruppos appeared around the same time that Suntour's patent expired, Shimano was able to have slanted derailers ready for sale to give SIS the best performance (and market acceptance) possible.
The difference with the slant parallelogram was that the parallelogram pivots were off-axis from being perpendicular to the axle, so that the shifting motion moved the cage further away from the axle as the larger sprockets were engaged.
Shimano spent years developing SIS, knowing full well when the patent expired. Thus, when the first SIS gruppos appeared around the same time that Suntour's patent expired, Shimano was able to have slanted derailers ready for sale to give SIS the best performance (and market acceptance) possible.
#3
Senior Member
Join Date: Mar 2005
Location: Pinole, CA, USA
Posts: 17,414
Mentioned: 24 Post(s)
Tagged: 0 Thread(s)
Quoted: 443 Post(s)
Likes: 0
Liked 27 Times
in
25 Posts
The Shimanos you linked are drop parallelogram designs, but the parallelograms are not slanted so the top pulley follows the shape of the cluster as it moves across. There was never any patent protection for drop parallelograms. It's the slant that was protected. The slant of the Suntour honor can easily be seen in that video you linked.
#4
Senior Member
Thread Starter
Join Date: Aug 2007
Location: Evanston, IL
Posts: 5,833
Bikes: many
Mentioned: 61 Post(s)
Tagged: 0 Thread(s)
Quoted: 1421 Post(s)
Liked 1,344 Times
in
737 Posts
Thanks. I was considering "slant" in the wrong axis. Now that I know what axis to pay attention to, I understand completely.
S
S
#5
Senior Member
Join Date: May 2011
Location: Oslo, Norway
Posts: 378
Bikes: 1951 Armand Carlsen, 1969 DBS Deluxe, 1949 Diamant, 1978 DBS Winner Tandem, 1955 Herkules... to infinity and beyond!
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 3 Times
in
2 Posts
The whole point of slant-par was to keep the top jockey wheel as close as possible to the sprockets, ensuring quick chain movement and crisp shifting. With a straight-par the gap between jockey wheel and sprocket increased as you shifted to smaller sprockets since the parallellogram more or less moved straight outwards.
#6
Senior Member
Join Date: Jun 2006
Posts: 20,315
Mentioned: 129 Post(s)
Tagged: 0 Thread(s)
Quoted: 3447 Post(s)
Liked 2,786 Times
in
1,967 Posts
Shimano spent years developing SIS, knowing full well when the patent expired. Thus, when the first SIS gruppos appeared around the same time that Suntour's patent expired, Shimano was able to have slanted derailers ready for sale to give SIS the best performance (and market acceptance) possible.
#7
Banned.
Join Date: Dec 2007
Posts: 27,297
Mentioned: 34 Post(s)
Tagged: 1 Thread(s)
Quoted: 378 Post(s)
Liked 1,407 Times
in
908 Posts
I sincerely thank you all for informing me on this, and Skip for asking the question.
Killer stuff, and when I repeat it someday, people will think I actually know something.
Killer stuff, and when I repeat it someday, people will think I actually know something.
Thread
Thread Starter
Forum
Replies
Last Post
Briareos
Bicycle Mechanics
1
07-13-12 09:07 AM