VintageSteelEU

I got recently Suntour VX-S (medium cage Vx from the late 70's) and after cleaning it looks and works great. The idea was to see whether I'm able to get it work in a satisfactory manner with Shimano Indexed shifters (SL-A400, Exage 300EX, 7 speed). The drivetrain is Shimano 600EX FC-6207 crankset (52/48), Wipperman 708 chain and Shimano CS-HG200 7 speed casette (12-14-16-18-21-24-28 version). The chainset is mounted on 113mm bottom bracket (68x113) as opposed to Shimano specification of 68x116, so the chainline is moved a bit to the left, but that generally never was a problem with the current derailleur (Shimano RD-6208), the chain rings have enough clearance, though of course the chain line is not as expected (but works perfectly fine with my riding style).
It seems I might be able to adjust it well enough to cooperate with the shifters, but during the initial test I found out I'm not able to use more than 6 sprockets. Derailleur cage is catching on the spokes of the rear wheel if I try shifting it to the 7th, lowest sprocket. That in itself wouldn't be too much of a problem, I don't really use the 28T cog and even 24T one is used briefly. But I don't like something not working exactly the way I want it to.
I thought, "not a big deal", I might build another wheelset and use 6 speed freewheel or something. However, decided to try it on my other bicycle, which has Stronglight 105 ter cranset (52/48 again, I believe), Wipperman 708 chain, Suntour New Winner (13-24T, I think) 6 speed freewheel and Suntour Power Shifters. I have Suntour Cyclone MK1 RD on it usually and that works fine. With VX-S I'm getting the same problem as on the other bike, with the difference that derailleur cage starts catching spokes from the 5th sprocket. The freewheel on this bicycle has more clearance between the chainstay and the smallest sprocket than the wheel with the casette, but I guess on both wheels the situation starts happening around 30mm from the chainstay.

Vx-S is supposed to support maximum cog size of 30T, so in both cases it should be perfectly fine. The L adjustment screw wasn't too deep, there was still room for the pralellogram to move further. Both wheels are dished correctly.
Never encountered anything like that with other derailleurs, no matter the make or model (Suntour, Huret, Shimano). The cage isn't bent, the hangers are straight. What am I missing here? Anyone has any suggestions / solutions?

dedhed

Honestly your best bet is to ask this in "Classic & Vintage" those guys will have a better idea and someone there has probably already tried this.

FBinNY 

Two likely possibilities.

1 if the cage is touching down near the lower pulley, it's a classic case of bent hanger. Solution--- straighten the hanger.

2- if it's touching high up by the upper pulley, odds are that cage width, from center of pulley to inner plate is more than the wheel allowed for.

As gear number increased, the spacing narrowed. The narrower chains allowed narrower RD cages which, in turn, allowed allowed less clearance behind the freewheel. This is especially true for freehubs produced after the 7 or more speed era.

The solution is simple----add a spacer to push the freewheel out until the RD cleats the spokes in low. Note, you might then need a spacer on the axle so the chain clears the frame in high.

oldbobcat

I'm looking at this rear view of a Suntiour VX-S.


What is the axle width between the dropouts, the customary 126 mm for 7-speed, or 130 mm? And are you trying to get this thing to index with your Shimano shifters? Because it isn't designed for that.

FBinNY 

Agreed that getting this to index is problematic, but there might be a serendipitous combination.

However he won't get there until he solves the low gear clearance problem first

FBinNY 

If you can't post a photo, at least a very detailed description of EXACTLY what's touching where.

FBinNY 

If you can't post a photo, at least a very detailed description of EXACTLY what's touching where.

Bill Kapaun

Get someone to hold the bike vertical.
Stand about 10 feet or so behind the bike and LOOK-
Is the plane of the center line of the bike parallel to the plane of the motion of the RDER.
IOW, is the dropout/hanger bent enough so the RDER tilts toward the wheel.

I did have an issue once when using a 23T largest cog on a hybrid designed for a 3?T largest cog. The RDER was "ticking" the spokes.
As the spoke tapers toward the hub, it gets closer to the RDER. A larger cog moves the RDER away from the hub toward the ground.

oldbobcat

And this serendipitous combination might be what's pulling the derailleur up against the spokes.

Somebody has to determine whether it's the alignment of the derailleur or hanger, a user error like a limit screw that's too loose, a system incompatibility like a shifter that's pulling more cable than the derailleur was designed for, or the derailleur design itself. Or a combination of the above.

First step is to put the bike in a stand, disconnect the shift cable, and shift into the largest (normally called "first") cog by guiding the derailleur with the left hand while pedaling with the right.Then adjust the inner limit screw so the cog, chain, and derailleur pulleys line up when viewed from the back. This should form a straight line from the top of the cog to the bottom of the tension pulley. If it isn't, something is bent. Straighten it or buy a replacement.

If it is, and the cage clears the spokes, then the cable should be attached and the tension adjusted so it hits this limit screw lightly in its tightest (first gear) position. Getting the remaining gears to index is your problem, but under no condition should you touch the low limit screw to get the other cogs to index.

If it is, and the chain doesn't clear the spokes, then perhaps the cage is too wide. This is a price-point derailleur and the cage is made of a relatively thick, soft aluminum. Also, it's made to accommodate wider 5-speed chains. Now, so is the Campagnolo Super Record unit on my Masi, now doing duty for 7-speed, but the cage is harder and has a thinner cross-section. Also, the shifter doesn't index, so I just slam the lever as far as it goes and I'm in my first cog.

But my first guess is that the limit screw has been adjusted too loose to allow the shifter to index for the other six cogs.

Andrew R Stewart 

I'll add that these ST ders had huge cage "thickness" The pulleys were thick (to work with the 7.8mm wide 5 speed chains still in use in the later 1970s. The cage plates were thick. The cages had a nut protruding from the cage plate's back side. Spoke catching was very easy when in the biggest cog. But not when in the second biggest cog. It's that detail I find strange.

As to indexing w/ any shift lever- ST never intended these ders to be indexable. So if it does manage to index shift well across the complete cog set it's by "luck" and not design. Andy

FBinNY 

Based on my reading of the OP, I believe the limit screw or any other adjustment is the problem. Limit screws issues, and trim errors would cause a derailleur to overshift, but that would be when or after a shift to low is completed. Here the OP is saying he can't get in to low before the RD cage hits spokes.

Of course, I'm taking the OP's text at face value, and that may be a problem. In my first response I referenced 2 possibilities, depending on where the cage was touching (top or bottom) and there may be other factors, but short of specific details, we're all throwing spaghetti against the wall to see if it sticks.

FBinNY 

I agree that they were thick, and remember how they demanded more then typical precision in limit adjustment since they used up almost all the clearance behind the freewheel. They were especially difficult with the Regina/Campagnolo combination which had less clearance than Shimano or Suntour hubs and freewheels.

But this case, as described, is much worse than usual, and the issue on different bikes pretty much rules the hanger, so we need to look to something truly odd.

Just maybe ----- the inner cage plate is upside down or inside out. That would possibly allow the inner guide rail to touch spokes just beyond the flange.

oldbobcat

Of course, all this is speculation until VintageSteele give us more clues.

FBinNY 

Absolutely, we're just wasting spaghetti till then.

VintageSteelEU

Sorry, didn't get notification about new posts.
To address the points made above.
1.) I believe I did assemble it correctly. Of course, I might be wrong, but it's not the first derailleur overhaul (I use mostly vintage components, so I'm generally familiar with their construction) and I did have schematics at hand (mostly to check the coil spring position, the construction itself is pretty much straightforward). It works great all the way to the problematic cog on both bicycles. Have a look at the photos below and if you see something out of place, let me know.
2.) Both frames have dropouts spaced to 126mm. The 7 speed casette has 12t sprocket nearer the DS dropout (just enough for a comfortable chain clearance, I'd say 3-5mm) compared with the 6 speed freewheel one (about 9mm clearance), which would explain why on the casette I can shift to 6th cog without problems and on the freewheel I can shift to 4th cog. Difference in spacing on the cogs on Shimano 7s casette and Suntour 6s freewheel + difference in DS dropout clearance means the inner RD plate gets in contact with the spokes when the parallelogram is probably at roughly the same position.
3.) I thought about the possibility of the hanger being bent. But firstly, every other derailleur I used on these frames, this including Suntour Cyclone (which I'm mentioning because it's cage thickness is approx. 17mm vs 16.5mm on VX-S. Clearance inside is 10mm on both), works fine. In case of the frame with Shimano RD-6208 indexing is very smooth and responsive from the smallest to the biggest sprocket and back. Secondly, what's a chance for the RD hanger being bent in the same or very similar way on both frames? I have no way to mesure the hanger angles more precisely, but they seem to be fine enough.
4.) Derailleur cage on Suntour VX-S is one piece, quick cage design. There is no physical possibility to put the inner cage upside down. The point of contact with the spokes is at the top pulley.

I was thinking about changing the jockey wheels and get some narrower ones. Because the Wipperman chain is approx. 7.8 mm in thickness (this measuring on the pin), I could probably modify some jockey wheels and reduce the cage thickness by about 1, which would probably help a bit. But probably not enough. On the 6 speed wheel I also have an option of re-dishing the wheel about 5mm to the drive side, which would increase the spoke angles on the DS. The problem here is that I'm using all the spacers, locknuts etc. in exactly the way they came with the hub. And I'm not sure if under the Maillard long locknut (they used locknut and spacer made from one piece of steel) I have any spacer I could move to NDS. Also, I want to use VX-S on the other bicycle, where I don't have enough clearance on the DS side to play with wheel dishing
Another option would be modifying the cage (and removing the bit that catches the spokes), but that's not an option I'm going to entertain I quite like that derailleur the way it is, thankyouverymuch

Here are the pictures:

FBinNY 

OK, we can now eliminate the basics.

Check the upper pulley for play. A badly worn pulley can move sideways, so the cage ends up more inboard vs. the chain.

SurferRosa

There you go. It's the derailleur.

What's the value when it's in perfect shape? $20?

VintageSteelEU

There is some play in both upper and lower pulley, however, this is the plastic wheels moving on the bushings inside them. The busings and shields are firm and there is no discernible play in the cage itself, not a fraction of a millimetre. I am going to try some new(ish) jockey wheels at some point next week, because there has to be a reason for the RD behaviour and I guess the only way to find out is through elimination. The previous RD I had on the 6 speed freewheel is Huret Success (cage thickness 14.5mm at upper pulley vs Vx-S' 16.2mm) and that one also has some play in the upper pulley. Well, something to do during the cold winter evenings, I guess

Well, probably yes, but why? Vx-S was first released around 1977 (this particular example is September 1980), so a period when 6 speed freewheels were common. The Maillard hub I'm using is from the same era (it's from the late 80's, but the model was around from the 70's), the freewheel is also Suntour (New Winner 6 speed, so from early 80's and with the same spacing as earlier models, it's not Ultra variety). So whilst I can say "fair enough" when it doesn't clear 7th sprocket on Shimano HG casette, and move on, not being able to use it on a 6 speed Suntour freewheel is a bit puzzling, to say the least I will probably try standard Vx (short cage) at some point. Generally they are anything from Ł20 to Ł35 in the UK, depending on the condition.
But short cage VX is definitely going to struggle with 28T cog, so I guess it will be time to make a custom casette with 26T max (which is on the cards anyway). Here's hoping a differently shaped inner cage isn't going to catch the spokes.

For people who were wondering, I did set Shimano shifters into friction mode. Indexing kind of worked for the first two shifts, albeit with struggles, but it was only after adjusting the H limit screw to put the pulley underneath the smallest sprocket of the casette. After that accumulation of errors was too much. So I am thinking that after careful adjustments in the middle of the casette, looking into cable pull ratios and introducing some modifications there is a good chance Vx-S "might" work with the indexed Shimano shifters of some kind (perhaps 8sp ones) well enough. So I very much hope to get back to that experiment at some point. But first, I have to figure out why on earth does the inner cage get into contact with the spokes.

Oh, this all is by no means crucial, I have a well working bicycle I ride daily and plenty of tinkering to do with the other one. It's just tinkering out of curiosity and for the sake of experimentation and also a relaxation technique. Next thing I might try before I get a standard Vx for testing will be Skitter RD (which I have somewhere) to see how that one is dealing with clearing the cogs.

FBinNY 

OK, so it's not the pulley itself, but something is causing the RD to need overtravel before the chain moves.

It may be the chain itself, or more specifically how the chain and pulley interact. When this RD was made chain plates were larger than the rollers, forming something of a V-pulley to keep the chain centered. Modern chain plates are just about flush with the roller. This makes shifting easier, but require deeper engagement between the plates of the inner links to retain the chain. So it's possible that as the RD moves across the pulley is sliding off, and the chain gets pushed by the cage plate instead. I looked at the photo, and see some patina that supports this idea, but it's not solid proof.

Don't get a new chain, but instead set your cell phone so it's focused on the area including the upper pulley and sprocket, then shoot video while shifting, so you can see if the chain is moving off the pulley. Or, use a dry marker or nail polish to color the inside of the outer cage plate near the top> then set the limit to protect the RD, and do some hard shifts as far as it will go and any scratches will confirm that the chain is coming off the pulley.

Once you confirm that, consider a more old fashioned 6s chain, or a more modern pulley, with washers if needed for width.

In any case a video is probably the most helpful way to see what's happening.

VintageSteelEU

The chain is new or almost new. On both bicycles. On the one with Shimano casette it's been replaced about a month ago, on the other one few months back, but I seldom ride that one. A video might be a good idea, something to try later this coming week perhaps.
I do have some Sedis chain for 6sp stored somewhere. Need to dig it out and see if I could use it.

FBinNY 

[QUOTE=VintageSteelEU;22736359]The chain is new or almost new. On both bicycles. ..../QUOTE]

I didn't mean old vs. new. More like old meaning vintage. It's about plate size and shape, not wear age.

VintageSteelEU

[QUOTE=FBinNY;22736362]Gotcha. Different chain designs.
I guess it'll be time to put the RD back on the bicycle, bicycle on the stand, take a video and then perhaps revisit the idea of trying different pulley wheels. I'm also looking now at SVX I got for parts (well, I was planning to use it, but it arrived with no chain tension coil spring), which has pulley wheels in a very decent condition, but also a cage (seems to be the short version) that looks like it might be compaible with Vx. Looks like I'll have to clean it tomorrow and either try it with the spring from the Vx or put the cage from SVX on VX and see what happens.

grumpus

Or fit narrower pulleys and space them to the inside of the cage, and hope that doesn't affect shifting onto the smallest sprocket.

VintageSteelEU

I'll look into this on Wednesday again. Cleaned the SVX today (and even polished, in case I ever find the pulley cage tension spring for it and I'm able to use the derailleur), so I'll be able to use its cage and pulley wheels (no play whatsoever here) with VX and see the results. And make a video of shifting with both cages. I guess these are the perks of using classic components

Andrew R Stewart 

I believe that the cage pivot spring (a square section wire which is less common than the round wire springs most think of) is shared by the VGT and the V Lux versions of this series. I also suspect (it's been a few decades since I had these apart) that the steel versions also use the same spring. VGTs are pretty common and should be easy to find in the used markets. Andy