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Suntour Symmetric shifter, does it "trim" or shift?

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Suntour Symmetric shifter, does it "trim" or shift?

Old 01-05-24, 02:37 AM
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Suntour Symmetric shifter, does it "trim" or shift?

Just picked up this old Motobecane Jubilee Sport with an old Suntour Symmetric shifter. Cleaned it up , reassembled . I'm not clear if the symmetric system is intended to "trim" the front derailleur position or actually perform a full on "shift" between chainring's which is how it's currently working.Im taking the word trim to mean in small increments.? If so, what would these small movements look like at the FD while shifting between rear cogs? Anyhow, I tried the basic adjustments with chain on largest rear cog, tensioned the FD cable with left shift lever forward, right lever pulled back.





I Placed a piece of tape to draw reference marks to illustrate the shifter maximum travel approximately under a 1/4" with that said trim would seem to make sense.?

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Old 01-05-24, 06:07 AM
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Trim.


i.e. shifting the rear full-range should not make the front shift in either direction, just move to follow the small change in chainline.

The only extra trick to shifting with these is that when shifting the front, you learn to get the cage centred on whichever ring you're shifting to, because that will change depending on where the rear mech is.
Half-step is thus very fiddly, it is much more suited to 52-36 or so, especially if you are running a wide (two ways) set of sprockets.
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Old 01-05-24, 06:46 AM
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Mine only trims.

That vise grip on the Jubilee Sport’s top tube is frightening. Maybe something like this will go on that cool stand?
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Old 01-05-24, 07:52 AM
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On a double it trims nicely, on a triple not so much.
You might find this interesting:

Test your wits - Suntour Symmetric reassembly challenge! With pics!

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Old 01-05-24, 09:14 AM
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Originally Posted by Classtime
Mine only trims.
That vise grip on the Jubilee Sportís top tube is frightening. Maybe something like this will go on that cool stand?
That said, interesting repurposing of what looks to me like an engine stand.
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Old 01-05-24, 11:26 AM
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Thanks Classtime. LOL most definitely would make for a welcome addition to my would be bike shop! Previously looked at those before improvising/repurposing the engine stand. I get it.

Thank you top506. Sounds like you're familiar with the system. I'm really looking for guidance on how to go about adjusting the system correctly. Before reaching out with a new post I read completely through the Test-your- wits- post, including many others. I'm thankful for all these great post thus far, gathering together all these bits and pieces of info. Just trying to wrap may head around how much the FD moves in or outwards with each shift at the freewheel and any additional pointers. including how to go about making the system work as intended.

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Old 01-05-24, 11:56 AM
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Suntour Symmetric shifter setup?
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Old 01-05-24, 12:41 PM
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My Trek 710 has those shifters with a regular AT triple.

I used the bike for a lot of spirited foothills riding about 15 years ago and the Symmetric function never did anything but what it was supposed to do, trim the front derailer.

I removed the shifter from the DT and oiled it from the back, all that it ever required.

The cable adjustment or lever position would have to be off for the symmetric function to initiate a chainring shift, since it doesn't move the front derailer's cable very far.

Sheldon Brown reported an issue with the Symmetric shifter function re-setting itself into uselessness, but after using Symmetric for a good while on doubles and triples I am convinced that only happens when the cable adjustment needs tensioning/adjustment.
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Old 01-05-24, 12:52 PM
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Originally Posted by oneclick
Trim.


i.e. shifting the rear full-range should not make the front shift in either direction, just move to follow the small change in chainline.

The only extra trick to shifting with these is that when shifting the front, you learn to get the cage centred on whichever ring you're shifting to, because that will change depending on where the rear mech is.
Half-step is thus very fiddly, it is much more suited to 52-36 or so, especially if you are running a wide (two ways) set of sprockets.
Thankyou oneclick. I'm totally new to friction shifting particularly Symmetric. this being my first road bike. I've only used index shifting at this point.Guess I'll be enjoying another learning curve.(I'm having a problem high lighting and/or using the quote feature.) I'll improvise. (quote)i.e. shifting the rear full - range should not make the front shift in either direction,just move to follow the small change in chainline. Thankyou for clarifying this and defining the difference. So shifting from the smallest cog to a larger how much movement should/would you see or measure at the FD? with double chain rings? how's the system adjusted to make these small realignments?

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Old 01-05-24, 01:44 PM
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Originally Posted by dddd
My Trek 710 has those shifters with a regular AT triple.

I used the bike for a lot of spirited foothills riding about 15 years ago and the Symmetric function never did anything but what it was supposed to do, trim the front derailer.

I removed the shifter from the DT and oiled it from the back, all that it ever required.

The cable adjustment or lever position would have to be off for the symmetric function to initiate a chainring shift, since it doesn't move the front derailer's cable very far.

Sheldon Brown reported an issue with the Symmetric shifter function re-setting itself into uselessness, but after using Symmetric for a good while on doubles and triples I am convinced that only happens when the cable adjustment needs tensioning/adjustment.
Thankyou ddd. Maybe a more appropriate accurate title and question would be- How to make a Symmetric shifter Trim instead of shift?

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Old 01-05-24, 01:46 PM
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Originally Posted by jzr756
...shifting from the smallest cog to a larger how much movement should/would you see or measure at the FD? with double chain rings? how's the system adjusted to make these small realignments?
One thing to keep in mind is that different derailers have different "actuation" or "pull ratios".

So unless the chosen front derailer is of the product family from that period of time, some degree of lessened or exaggerated cage movement might result.

And the choice of rear derailer could also affect things in this way, as some will require more or less lever movement to effect the same amount of lateral movement of the chain.

And finally there's the chainstay length as another variable affecting how far that the front derailer cage should move, as well as the chainring-size difference, which is also critical in that it affects the distance and thus length of chain between the chainring teeth engaging the chain and the front derailer cage.

As far as the symmetric shifters causing unwanted up- or down-shifting, if it's a double, then the cable tension adjustment would seem to be the first thing to visit, with the cable tightened or perhaps even loosened depending on which kind of unwanted shift is occurring (up- or down-shift).

With a triple, one might experience an unwanted shift if the cage happened to be positioned to either extreme of where the cage is positioned over the middle chainring. So the left lever may need manual trimming from time to time following any shift of the front derailer.

Could you describe the exact unwanted-shift scenario/type?

One thing about analog front shifting is that it's always a bit quirky when a triple crankset is being used. It's kind of entertaining once the user becomes familiar with the range of behaviors and the lever movements needed to keep the chain flowing!

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Old 01-05-24, 01:58 PM
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I've always run those on triples and find they help but don't quite do all the trimming. On a 126 OLD 7-speed and a Cyclone Mk II I will probably "have to" do one or two trims by hand if I run across the entire cassette. (The quotes because I have done thousands of rear shifts without Symmetrics and not done the trimming and I am still alive, well and well fed. I probably have shortened the lives of a few purists who have accompanied me and my FD chain rubs but they never told me and I remain happily oblivious. And yes, in my racing days I had to buy new Cyclones every year and a half or so. Paper thin cages.)

I'm guessing there is a particular FD(s) that work perfectly with the Symmetrics and that it is not one of the SunTours I have used with it. Maybe the Superbe? The Symmetric came on my circa '83 Pro Miyata as did the Superbe derailleurs but the bike had seen a lot of time outdoors in the rain. Symmetric cleaned up just fine but the Superbes are basket cases.

Edit: When you take the Symmetric apart, be sure you have the right-hand "shaft" in the correct position, not 180 degrees out. Get it wrong and the FD will anti-trim and thwart all your intentions of clean, effortless shifts and instead requite manual trimming every shift! If you see this, take off the right lever, loosen the cables and turn the shaft 180 degrees.

Second edit: I wonder if that wrong assembly of my first edit will cause unintended shifts. I didn't see it when I ran my Symmetric wrong when I first set it up but those rides were pretty awful.

Last edited by 79pmooney; 01-05-24 at 02:08 PM.
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Old 01-05-24, 03:12 PM
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Originally Posted by dddd
One thing to keep in mind is that different derailers have different "actuation" or "pull ratios".

So unless the chosen front derailer is of the product family from that period of time, some degree of lessened or exaggerated cage movement might result.

And the choice of rear derailer could also affect things in this way, as some will require more or less lever movement to effect the same amount of lateral movement of the chain.

And finally there's the chainstay length as another variable affecting how far that the front derailer cage should move, as well as the chainring-size difference, which is also critical in that it affects the distance and thus length of chain between the chainring teeth engaging the chain and the front derailer cage.

As far as the symmetric shifters causing unwanted up- or down-shifting, if it's a double, then the cable tension adjustment would seem to be the first thing to visit, with the cable tightened or perhaps even loosened depending on which kind of unwanted shift is occurring (up- or down-shift).

With a triple, one might experience an unwanted shift if the cage happened to be positioned to either extreme of where the cage is positioned over the middle chainring. So the left lever may need manual trimming from time to time following any shift of the front derailer.

Could you describe the exact unwanted-shift scenario/type?

One thing about analog front shifting is that it's always a bit quirky when a triple crankset is being used. It's kind of entertaining once the user becomes familiar with the range of behaviors and the lever movements needed to keep the chain flowing!
Thanks again dddd, went back for a second look after posting it no longer shifts but the FD never really moves. as measured with a ruler between the inner FD cage and the frame. The chain does remain within the confines of the FD while shifting to all 7 cogs without chain rub,as I think would be normal in a non Symmetric system. It looks like at some point the freewheel was switched over from a 6-7 speed. I believe the original was a six

Last edited by jzr756; 01-05-24 at 03:18 PM.
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Old 01-05-24, 03:21 PM
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I used them for years. Really nice friction shifting feeling, I greatly prefer it to suntour friction power shifting that so many others here love. I like for the cable to move where I want it to be, not to a destination pre-defined by clicks.

On a 6 speed freewheel double crankset bike, it worked fine for years without needing any adjustments. Highly recommend you re-read some of the posts and threads already made on this site and re-do your setup. It works!
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Old 01-05-24, 03:55 PM
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Originally Posted by Piff
I used them for years. Really nice friction shifting feeling, I greatly prefer it to suntour friction power shifting that so many others here love. I like for the cable to move where I want it to be, not to a destination pre-defined by clicks.

On a 6 speed freewheel double crankset bike, it worked fine for years without needing any adjustments. Highly recommend you re-read some of the posts and threads already made on this site and re-do your setup. It works!
Thanks piff. Interesting on your preference towards straight forward friction shifters. a preference of many. Really looks like it's requires some practise. I been thinking about changing over to one of those Suntour power shifters on the left side of my 80's Suntour equipped friction/index ATB. . I get it! every time I reread these posts I glean a little additional info ea.time
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