Bianchigirll 

When did Dura Ace steal the Slant Parallelogram design from Suntour? I think I missed out on a real deal for an early DA group but I want to have a slanted RD for the smoother shifting. This was on FB for only $200 depending on currency exchange

I looked over Velobase but I really can't tell when it acquires the slant design.



I was thinking this would look great, but kind of retro, on the "Speckled Trout" Bertoni

bikemig 

Suntour's patent ran out in 1984:

US Patent 3,364,762 - SunTour

Kuromori

Shimano slant parallelograms started with SIS, so 7400. RD-7300 was the weird AX thing. RD-7200 is merely a dual sprung dropped parallelogram that was an evolution of the Crane.

JohnDThompson 

The derailleur in your picture is pre-slant parallelogram. As @bikemig notes above, SunTour's patent on the design only lapsed in 1984, and the first Shimano slant-parallelogram derailleur, the Dura-Ace 7400, came out late that year with the first SIS indexed drivetrain:

Bianchigirll 

OK Thanks. That was what I thought, but even the 7400 doesn't look that slanted. I think I'll just keep looking for a VGC Superbe or Sprint or 1st Gen Chorus that won't break the bank

John E

Once the SunTour patent expired, almost everyone copied the design as quickly as possible, because it makes so much sense.

Bianchigirll 

Except CampI. I am sure shipmano had there RnD dept experimenting (using all that fishing reel money) long before the patent ran our. CampI just kept the same old design but with a shiny new face

mountaindave 

They did. You don’t just happen to have a fully functioning indexed rear derailleur that will soon become the standard for an entire industry in the same year that a patent expires without having done metric crap-ton of R&D first.

52telecaster

I've got one of the old 600s that is ok but definitly not smooth.

L134 

Interested in either? I also have a black Cyclone which I believe is first generation.

romperrr 

I'm interested in the black superb if BG passes

repechage

you are correct Bianchigirl
Shimano was keenly aware of the looming patent expiration. They had designed, tested and tooled up for the 7400 With SIS and were ready to deliver. Shimano was cunning, 6, 7, 8 cogs, then integrated brake/ shift, tipped the scales and got freehubs popular, which had been around since the EX series but resisted.
( note the planned obsolescence along the way- design stability was over )

Campagnolo by their patent applications was desperate to come up with a patentable alternative in the early 80’s. There was none, the closest that was employed was the extending diagonal rod in the Croce’ mech and the A, B variable geometry - I think used on Chorus.
they really struggled to avoid using the slant parallelogram- even after it was open source.
almost cost them the company.
eventually they got going. Dark days until they did. Must have been a terrible time there, they had been the developer of patents that gave them an edge- then were out developed. Not humble enough to accept outside concepts.

mountaindave 

FIFY

The graphic looked a lot like Campy Super Record (without the slant parallelogram) which in turn looked a lot like first gen Cyclone (the origin of the slant parallelogram). So the real winner here is clearly...



Photo from Disraeli Gears

smontanaro 

I believe the only company that might have stolen the slant parallelogram was Rino. Everybody else waited until the patent ran out.

Kuromori

It was really only Shimano poised to jump on it because they realized they could make an indexed system that worked well using their tooth profiles and chain. Everyone else was mostly following Shimano.

After SIS was introduced, it became about trying to make a working index system, which was either done by copying Shimano that copied the slant from Suntour, or trying to come up with alternative designs and failing as with many of Campagnolo's Syncro designs. I'm having a hard time thinking of any slant designs other than Suntour and Rino that were meant only for friction, and Rino was making Suntour knockoffs before the patent expired. You can really tell the slant parallelogram derailers are Shimano RD-7400 derived when they have a sprung B-pivot.

dddd

OP mentioned possible differing degree of slant. I have wondered about this, but find it hard to visually verify.

Campy did also have an Athena (and later Xenon) Synchro derailer with a slanted parallelogram, but with very little in the way of a drop-down knuckle (just merely an offset up top would be one way of looking at this). They apparently didn't want to appear "copycat", but soon relented as pressure mounted to achieve indexing perfection with the longer cables of integrated shifters. So this earlier slanted design never made it past when Ergolevers were fitted at these respective Athena and Xenon levels.

Slanted parallelograms have a problem though, which ultimately limits how much slant will still work with how much return-spring tension. Only a non-slanted parallelogram will eliminate any road impact vibration from trying to bounce the cage inward and outward (with only return-spring tension and the cable resisting this tendency). Note that traditional non-slanted derailers are not completely immune to bump forces tugging on the cable and resisting the return spring, but are very much better in this regard when using the smaller end of the freewheel where speeds tend to be highest.

I don't really see any difference between mtb and road derailers in terms of their slant angle, though there are obviously other changes to the cage, springs, etc which allow them to accomodate larger cogs. It's surprisingly subtle how the cage itself helps clear larger cogs on the mtb versions.

I believe it was Colnago dealers who had to strip Rino derailers off of bikes that had been shipped (to the US at least). I came across supplier of these previously-installed NOS derailers some years back, and who was helping to clear out old stuff from the bins at a big Colnago dealer in SoCal.

T-Mar

Oh there is significant difference, or at least there can be. Several years back, I bought a Deore XT rear derailleur on Ebay. Everything looked good in the picture but when it arrived, I soon realized that it had been rebuilt with a different top or bottom pivot casting, so that the cage wasn't parallel with the dropout hanger. There was ~15 degrees difference. Boy, was I PO'd.

Bianchigirll 

I like the 'white' one

HTupolev

Sometimes the difference is small because the MTB derailleur isn't trying to accommodate a significantly steeper cluster than its road counterparts.

MTB rear derailleurs for 2x/3x setups have usually been intended for large cogs of somewhere from 28 to 36 teeth, but with very long cages and a lot of the drivetrain's range coming from the chainrings.

Meanwhile, the rear derailleurs that are aimed at 1x setups with enormous cassettes usually don't need steep parallelograms because they use a large offset between the jockey wheel and the pivot to manage chain gap. This doesn't create any problems if you have no front shifting, and arguably has the benefit of making the rear derailleur "adjust" itself for different cassettes.
SRAM has even made modern 1x-specific rear derailleurs with old-school-Shimano-esque dropped parallelograms.

To add some recent shenanigans into the mix...
It's always been interesting that nearly all modern derailleurs use both a sprung b-pivot and a slanted parallelogram. If the parallelogram roughly matches the slant of the cluster, and if the jockey wheel is placed concentric with the a-pivot, the derailleur should enjoy good chain gap and be almost totally unaffected by front shifts. It will also be mechanically simpler and, since you're not worried about how the derailleur's tensions balance against the b-pivot, you potentially have more freedom in selecting the spring for the a-pivot (and any damping, like with clutched derailleurs). Or, put another way, "why not do an indexed interpretation of a SunTour GT derailleur?"
Anyway, I was putting together a new gravel build, and I chose Shimano's RD-RX810 for the rear derailleur. It uses Shimano's 11-speed road cable pull, it has a lot of wrap, it's intended to be tolerant to wide front differences, and it's clutched to keep things well-behaved on the rough stuff, and all these things seemed to make it a good match for what I was doing. As I took it out of the box and inspected it, I realized that it had no b-pivot spring, and that the jockey wheel was concentric with the cage pulley. It turns out that a number Shimano's non-1x "shadow"-geometry derailleurs are like this!

L134 

The one on the left? I tried sending a pm, did you get it?

Kuromori

I'm pretty sure all shadow, all SRAM (from the first SRAM derailer) and some Microshift lack sprung B pivots. Some have small offsets. Dual sprung pivots give more flexibility in gearing choices, but the single sprung pivots seem to help in reducing chain bounce off road, and I can't imagine a clutch would work very well with a dual sprung derailer.

Hudson308 

...and I'm interested in the black Cyclone, depending on your price.

L134 

sent you a pm.

L134 

sent you a pm.

gugie 

Dunno. I think the Huret Jubilee is #1 , followed by SunTour Cyclone first gen.

But looking at that Dura Ace, it's gotta be in the conversation.