Suntour VGT RD?

[Tom Norton]

On another group a fellow was talking about his upcoming tour and the specs of his bike. When he listed his RD it was the above mentioned. He is pairing it with a 9 speed cassette.
I have tried the same RD on my Velo Orange Polyvalent with a 9 speed cassette and it was a no go.
Am I missing some trick???

[satanas]

IIRC, the V-GT went out of circulation around 1980 when the VX-GT replaced it. We sold literally thousands on bikes back then, but I don't recall ever seeing anyone attempt to use either the V or VX with anything more than 6 speed freewheels. Quite a few derailleur back then had trouble coping even with 6 speeds; I had to Dremel my Jubilee slightly to get it to work.

Other than nostalgia, I cannot see any advantage in using a V(X)-GT these days, given any modern index-compatible RD should outshift it handily, and will easily handle wider cassettes. Replacements are probably both cheaper and easier to find too, unless one still has a box of NOS Suntours on hand. My vote would be to keep the Suntour as a museum piece, on a suitable UJB or other period frame.

Later,
Stephen

[Tom Norton]

Thanks for the reply.

[Reed Kennedy]

I'm currently running a Suntour Cyclone GT Mk1 with a 10 speed setup on my Fitz rando:

https://photos.app.goo.gl/CrKCwVovYoyhbgWx5

The cassette is an Ultegra 6700 12-30 and the chain is a KMC X10.93. So far I've ridden a couple thousand miles including numerous 200k brevets, a 300k, a 400k, and a 400 mile week long mixed terrain tour. Everything works splendidly with no downsides that I can perceive. No modifications needed.

This bike actually started out with a modern index-compatible rear derailleur like Stephen recommends:

http://notfine.com/bikes/pinkfitz/IMG_1562.jpg

I switched it to the Suntour for a specific reason: The Simplex Retrofriction shifters that I love don't pull very much cable, and would swing through almost 180 degrees of travel to get from the highest gear to the lowest. The shift lever was virtually parallel to the downtube in each extreme, making it clumsy to grab and shift. The Cyclone requires less cable pull for a given amount of travel, and works much better with these shifters. I have a modern Shimano rear derailleur and Rivendell Silver shifters on another bike, and the Suntour seems to shift just as well, no better or worse. (For me, shifting friction with downtube shifters.)

The Suntour Cyclone also has a convenient open cage making some mechanical work easier, and is beautiful to my eye. But these are just gravy, the main thing I like about it is how it works with my favorite shifters. That's been enough for me to lay in a small stockpile of spares.

Tom, when you say the V-GT was a "no go" for you, what do you mean? What didn't work? I'd thought the Cyclone GT was nearly interchangeable with the V-GT, and that the main differences was aluminum vs steel parallelogram side plates. But perhaps there's more than I'm aware of? Different pulleys, perhaps?

Best,

Reed Kennedy

San Francisco, CA

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[Gerhard Kohl]

Hi Reed,

on the linked image it looks like that it could be the Sun XCD derailleur, which has the same pull ratio of 1.7 as the standard Road Shimano derailleurs (up to 10Sp. for Road, and up to 9 Sp. for MTB). The Suntour has a pull ratio of 1.55, which is less.
So you would need more pull on the shift levers than for the old Shimano or SunXCD derailleurs.
Or is your old derailleur one of the newer Shimano models, an older Campa or an SRAM. They all would have a lower pull ratio than the Suntour models, and explain your observation.

And I can confirm that both the V-GT and the Cyclone Suntour derailleurs work fine with up to 9 Sp. I never tested 10Sp, but I assume it would work
Why shouldn’t it? Besides that it will get a bit more fiddly to sort the gears.

Right now I use ithe Cyclone derailleur with a 7Sp. Cassette with 34 as the largest cog.
Here the Cyclone does a better job than the V-GT in terms of generating less chain noise when the chain angle is at max.

By the way the Cyclone is better suited for Rinko than the V-GT, since it requires less space behind the rear drop outs. The V-GT is more bulky.

Gerhard

[Stephen Poole]

AFAIK, all the contemporary Suntour RDs at any given time (pre MTBs) were pretty much functionally identical. I had a Cyclone GT for a while and while it was a little lighter than a V and looked a bit nicer it shifted about the same (as did the cheaper, heavier ones like the Seven and Honor), and the cable clamps on the Cyclones savaged cables, unlike the cheaper ones. I duly sold it and bought another Duopar, which broke about a week after.  :-(

I'll freely admit that I don't like either friction shifting or downtube levers, though I've used both when I've had to. So, *for me* there's no practical reason not to use a modern derailleur; YMMV. That said, I still have a number of pre-index derailleurs in the "museum" (aka shed), but don't use them much. My next derailleur will probably be an Ultegra RX, with Dura-Ace 9120 levers...

Later,

Stephen (who thinks function trumps form, but wonders if it's okay to use the word "trump" about anything except cards these days)

[Reed Kennedy]

Hey Gerhard,

The derailleur in the "before" picture (where the bike is cleaner and not wearing a bag) is a Shimano Ultegra from the 9 speed generation, like this, but the medium / long cage version:

http://velobase.com/ViewComponent.aspx?ID=40EE0EFB-5134-49A5-8BC0-DDA27B68D308&Enum=108&AbsPos=4

I'm not sure how square the pull ratio numbers you listed with my experience. I know the 1.7 ratio for Shimano and compatible stuff is correct, would you mind letting me know where you came by the 1.55 ratio for non-indexed Suntour stuff? 

Frank Berto's wonderful "Upgrading Your Bike" book doesn't show numbers for the older Suntour models like the Cyclone (as they were well out of production by the time it was published) but it does show the Shimano SIS groups (1.7 ratio) requiring significantly more cable travel to shift the rear derailleur from the smallest to largest sprockets (0.72" - 0.76") than the old non-indexed stuff (which was all in the 0.5"-0.6" range). (Pages 114-117, available here: http://notfine.com/bikes/books/Bicycling%20magazine's%20complete%20guide%20to%20upg%20-%20Berto,%20Frank%20J.pdf )

I figure either:

A) I set up my Ultegra 6500 rear derailleur badly wrong and somehow never noticed 

or

B) That 1.55 ratio number you list for older Suntour friction stuff is not quite right

You can see in this picture how far back I had to pull the shift lever to get in to the lower gears:

http://notfine.com/bikes/pinkfitz/IMG_1559.jpg

Perhaps there was a ton of slack with the lever all the way forward and the highest cassette cog engaged? But I can't imagine I would have let a bike leave the garage like that...

Or maybe I goofed somewhere else? Would love to hear thoughts.

Also curious: Why does the Cyclone beat the V-GT at wider chain angles? I'll admit that mine gets a touch noisy when in the lowest cassette cog.

Best,

Reed Kennedy

San Francisco, CA

[Stephen Poole]

If one derailleur is more or less noisy in high and/or low gears than another it's likely the cages or hangers are twisted differently. This used to happen quite often, and I re-aligned the lower jockey wheel (by bending the cage plates with multi-grips) to quiet things down when necessary. This was quite often needed after crashes; I doubt there's any design difference involved, but who knows?

[Reed Kennedy]

Good advice Stephen! My Cyclone GT Mk1 is much quieter in the highest cassette gear than the lowest. I'm fairly certain my chainline is correct, so I'll take a shot at bending the jockey cage a bit.

Best,

Reed

[Stephen Poole]

I suggest proceeding carefully,  and testing frequently. There's no need to remove the derailleur when doing this, and that would just slow the process and increase the risk of acting hastily due to frustration.  :-)

As long as ultra-violence isn't used, changes are easily reversible.

Sit bender cave,

Stephen

[Gerhard Kohl]

Hi Reed,

I have to admit I never tested it myself. I looked up my reference Excelsheet I've created some time ago, when I started analyzing what types of shifters and derailleurs I want to work with my Bespoked Randonneur Frame.
And in that table I have noted down a actuation ratio of 1.55 for the Suntour Cyclone Mark GT II.
But I can't remember where I digged up that information and I was not able to find it again with some help from Google.
So you might be just right with your statement.
In case I will find it again and I still remember that post, I will update it here.

And that chain noise was a pure observation and it could very well be just a slightly misaligned pulley plate is causing that.
I did not further investigate it, since I prefer the Cyclone model because of the look and that it works better for Rinko.

Gerhard

[Reed Kennedy]

Thanks Gerhard, good to know it was a Cyclone GT Mk2 you were talking about. I did some digging around and, while I haven't found anything terribly official, here are two interesting posts from elsewhere:

A post by "amediasatex" stating that the Cyclone Mk1 is one of the highest pull ratio derailleurs he measured, at close to 2:1

https://forum.cyclinguk.org/viewtopic.php?f=5&t=123321#p1251041

A post by Dave Mayer stating that the different Suntour friction models had different ratios, though generally higher ratio than Shimano:

https://www.bikeforums.net/bicycle-mechanics/852284-suntour-rear-derailleurs-compatible-shimano-indexing-shifters.html#post20119202

Given the significantly different clamp location between the Cyclone Mk1 and the Cyclone Mk2 I wouldn't be surprised if there was a marked difference in the pull ratio between them. 

Someday, perhaps, I'll measure the pull ratio on my Cyclone Mk1. Anybody have advice on how best to do that?

In the meantime, I'll continue to sing the praises of the Cyclone Mk1 with Simplex Retrofriction shifters and a modern 10 speed cassette. I don't imagine there are many who desire both friction downtube shifting and this many speeds, but to those few of us who appreciate it, this is a pretty sweet setup.

Best,

Reed

[Brad]

As wonderful as the Suntour derailleurs of that era were in comparison to their competition, the later/ last iterations of Suntour derailleurs are even better.  Take a look at the Suntour 4050 with friction bar ends.  Sweet.