Classic & Vintage - Weak RD, what to do?

My Bianchi has Suntour Cyclone derailleurs. Smooth, fast to shift, quiet, light. But the RD has a problem: It doesn't want to go onto the smallest cog (smallest of 6). The stop screw isn't the problem, the parallelogram spring is. Or springs are, for there are two of them. The cable and housing are newish Jagwire and operate smoothly. The housing is a bit stiff so it appears to be wishing it didn't have to bend quite as much as it is needs to to enter the back plate of the parallelogram. But the biggest problem is simply that the springs aren't very strong.

Any thoughts on what else I can do to help this? Disassembling the parallelogram doesn't look feasible.

I noticed this problem when I first assembled the bike but managed to overcome it with lubing, bending, coaxing, and pleading. The problem has returned. I don't have many occasions to use the small cog, but I noticed it when cleaning up after this weekend's ride. No point in having a 6-speed FW when you can use only 5.

http://users.rcn.com/jimmuller/pics/grunge1.jpg

Your Cyclone is now like Louis CK's incurable, sh***y ankle. It's just worn out.

Perhaps a derailleur surgeon could transplant some donor return springs from a cadaver Cyclone, but you're not an athlete so maybe you should just take 10 Aleve, watch this (https://www.youtube.com/watch?v=ey4WSb-BVDQ)and call me in the morning.

Thats a funny looking RD! ;)

http://users.rcn.com/jimmuller/pics/grunge1.jpg

The hanger isn't bent right?

Have you cleaned and lubed the RD itself? And I have a busted Cyclone. I may be able to offer a spring, assuming it's transplantable.

Its probably at the end of its travel limit.....way out there spring tension is at minimum.

Assuming its spring tension:

A: you need to move the high gear cog closer to the mid line of the bike. There are two options, first switch to a narrow freewheel, and second repace the hub. Respacing the hub isnt the best idea because you'll need a dish change.

If its something other than the spring:

a: 'd' screw needs to cranked in....or our depending on the angle.
b. worn jockey wheels wiil do it
c. too tight of a cable will do it. it's friction shifting so extra slack is ok

Go back a 5-speed Jim - or maybe 3 - like a true-blue C&V'er. :)
(No sense getting all hot and bothered with those consarned new-fangled 6-speed freewheels.)

Auchencrow, you're positively backwards. In a good way.

I don't know, so I'll ask a stupid question here. Is the spring not replaceable on SunTours?

Auchencrow, you're positively backwards. In a good way.

I don't know, so I'll ask a stupid question here. Is the spring not replaceable on SunTours?

They're located inside the parallelogram plates that are secured with swaged pivot pins - no small chore to remove and reinstall I'm sure.

Yowl, such an awesome range of answers! Some even helpful, maybe, in a mis-directing kind of way! :)

As for it moving through its full range, I can encourage it with my fingers and it works just fine, so I could just treat it like an old-fangled pre-shift-lever derailleur. I might need longer fingers though. More of 'em too in case I break one off. Or re-grow one after I break it.

No, it's just a weak spring. It will move, but it's lazy and won't move all the way out without encouragement. The cable is plenty slack.

The springs may be replaceable but to do so I'd have to punch out the pins which hold the parallelogram together and then somehow get them back in again. If I was going to do that I might as well just re-bend the springs. Never done it before but I could try. If worse comes to worse I have a Vx that will work just fine, and spare parts for another Cyclone. But dang, that 1st-gen Cyclone is purtty. And smooooth. I'd hate to lose it.

I don't mind re-dishing the wheel. I like doing wheels, even got a new truing stand for Christmas! But the FW is what it is and I don't feel like taking it apart, couldn't gain but so much lateral space anyway. Re-spacing sealed-bearing Mavic 501 probably isn't an answer.

Thanks for all the input. I'll rest my ankle, up my game, take it to the next level, do some stuff, execute the game plan, and maybe try bending the cable housing so that it encourages the derailleur to move. Or go with the Vx. Or leave it alone and come to understand that I never use that cog anyway. Around here 75% of every route is uphill anyway.

Classic worn out cyclone. They are known for their week springs. nothing less, nothing more. You notice it works okay when the spring is more stretched. You could add a washer to the drive side of your axle and a washer to the upper pivot to move the derailleur further away from the high gear and thus move the high gear into a stronger area of the spring travel (make sense?). Or you could start looking for a new derailleur. You could also attempt the surgery, that would be pretty cool but very difficult for it to come out unscathed, if you go to the trouble don't use a used cyclone spring for cripes sake! those are the Achilles. Find a stronger spring from another derailleur.

Whatever you do, don't rebend and reuse the spring after all the effort of dismantling the derailleur. IF you can find a donor spring that is not 'set' like your current one, that would be a good bet. Another option, if you can figure out the details, is just shim the existing spring a small amount to add a little preload.

Or leave it alone and come to understand that I never use that cog anyway. Around here 75% of every route is uphill anyway.

I know I aint much help. But I like this option Jim.

Maybe you could put a little spacer between the spring and the place where it rubs on the inside of the parallelogram. This would wind up the spring just a tiny bit more. You'd have to have a low friction surface, though, so this suggestion probably won't work.

Classic worn out cyclone. They are known for their week springs. nothing less, nothing more.

I've learned about this too; I have a newer Suntour (XC) with the same problem. Never had a Shimano or Campagnolo RD with a weak spring.

it may not be the spring. remember that as the gears get higher, the parallelogram is collapsing. one piece is supposed to fit inside the other as it collapses. anything, a ridge, junk, a worn pin can cause the two pieces to hit one another and prevent them from nesting properly. as they age, a bur or ridge can be created on the large outside piece of the parallelogram. the fact that DR's use the small cog so rarely just amplifies the problem.

or get a different derailleur, install and go for a ride.

I fixed my old suntour deraileur - your spring is not worn out, it is just a design flaw. I could never get mine to drop into the smallest cog from day one. What I did was was drill a hole in the derailleur body directly over the end of the spring. Then I threaded a machine screw in to "pre tension" the return spring. I etched a slot on the end of of the screw with a dremel tool to engage with the return spring, effectively locking it in place at any tension. Worked like a charm,

^ that's a good idea if your machining skills are up to it. I always thought the springs kinda slid along the inside of the parallelogram though?

I fixed my old suntour deraileur - your spring is not worn out, it is just a design flaw. I could never get mine to drop into the smallest cog from day one. What I did was was drill a hole in the derailleur body directly over the end of the spring. Then I threaded a machine screw in to "pre tension" the return spring. I etched a slot on the end of of the screw with a dremel tool to engage with the return spring, effectively locking it in place at any tension. Worked like a charm,

Wow, I'm impressed enough to wonder why no manufacturer that I am aware of has ever incorporated a "tension screw". At least Campy provided a bolt to allow spring replacement in earlier Nuovo and Super Record.

Don't be too impressed with my machine tool skills - handheld power drill through aluminium, then force feeding the screw in. I may have used a sheet metal screw with a self tapping tip - I don't quite recall. You do need to drill the hole in the right spot, but I think the edge of the s pring was in the corner of the "box", so it wasn't all that difficult to figure out where to drill the hole.

You're method/execution might not be pretty but the idea is great.

Another option, if you can figure out the details, is just shim the existing spring a small amount to add a little preload.


Maybe you could put a little spacer between the spring and the place where it rubs on the inside of the parallelogram.

Good idea, OC and NG. That may not be too hard.


What I did was was drill a hole in the derailleur body directly over the end of the spring. Then I threaded a machine screw in to "pre tension" the return spring.
Neat idea! One I'm likely to thoroughly botch too.

Much to consider here. Thank you all!

Great bunch of folks. I like fender's idea best, go for a ride.

Wow, I'm impressed enough to wonder why no manufacturer that I am aware of has ever incorporated a "tension screw". At least Campy provided a bolt to allow spring replacement in earlier Nuovo and Super Record.

Early 90s shimano had a tension screw- I know for a fact that 735 XT and the corresponding LX RDs had a little cam with a flathead screwdriver slot that you could rotate around to several different index points to set preload on the spring. (halfway down linked image, on the right) (http://www.disraeligears.co.uk/Site/Shimano_Bicycle_System_Component_-_91_Page_51.html) Pretty sure at least one generation of tricolor had this as well. I have almost no experience with XTR or DA of the era to say definitively either way. So I won't.

Unfortunately, in a transition to "light action" shifting (or, according to some, as an effort to calm the rising surge of gripshift converts by reducing the RDs capability to keep the cable taut, rendering gripshift unreliable at its job), shimano changed their parallelogram springs to coils from corner to corner and greatly reduced the return tension. This meant that contemporary rear derailleurs (the 737 era of XT) were incompatible with gripshift.

This created a space in the market for aftermarket hacks to get the two systems to play nice. There were two schools for compatibility: reduce friction in the cable or increase the return spring. It was then when we first encoutered the $40 per set GoreTex cables and housings, and, more bizarrely, the era of the gripshift bassworm. The bassworm was a piece of surgical tubing that would sit in the chainstay cable stop and provide supplementary return tension for the cable as the shifter released it. I guess it also kept the rearmost length of housing from getting clogged up, but the primary purpose was for spring assistance.

Bassworm:

http://i.imgur.com/NVo8r.jpg

http://i.imgur.com/1kMqo.jpg

http://i.imgur.com/w90NZ.jpg

That's kind of a long way to go to suggest you look into something like a gripshift bassworm to assist a weak return spring, but I was on a roll.

washer between derailleur and dropout hanger.

washer between derailleur and dropout hanger.

"For every complex problem there is an answer that is clear, simple, and wrong." - H.L. Mencken



Your answer, however, is the exception that proves the rule. That's fookin' brilliant.

Wow, I'm impressed enough to wonder why no manufacturer that I am aware of has ever incorporated a "tension screw".

Shimano did....

I fixed my old suntour deraileur - your spring is not worn out, it is just a design flaw. I could never get mine to drop into the smallest cog from day one. What I did was was drill a hole in the derailleur body directly over the end of the spring. Then I threaded a machine screw in to "pre tension" the return spring. I etched a slot on the end of of the screw with a dremel tool to engage with the return spring, effectively locking it in place at any tension. Worked like a charm,

Ding ding ding, I have seen this repair, it works. That and on the Cyclone, one thing I never really liked is that the cable has to bend right before the anchor point. A more limber cable, even a now rare Campagnolo braided cable will help.
I know many like these units, but they were not without fault. They are stylish and light, so for that they get a pass.

tell that derailleur to HTFU!

Ding ding ding, I have seen this repair, it works. That and on the Cyclone, one thing I never really liked is that the cable has to bend right before the anchor point. A more limber cable, even a now rare Campagnolo braided cable will help.
I know many like these units, but they were not without fault. They are stylish and light, so for that they get a pass.

Come think of it, I probably got the idea for this mod on Bike Forums!

There is almost always room for improvement in the cabling, such that a reduced amount of spring tension is needed. Today's 10-speed shifters require almost perfect cabling from the get-go or won't always shift out on the road.
There are sealed ferrule available for the housing ends to preserve the smooth action, I salvage these from shop's discarded housing pieces because they are rather expensive.
Normal grease is not the best thing for modern cables as it almost always contains metallic extreme-pressure additives that are far less than ideal for plastic rubbing surfaces, and it is far too viscous as well.

A simple photo of the derailer fitment would at least clear up whether the cable housing is long enough and routed as smoothly as can be.

New cable housing back there will at least be free of any friction-causing dirt that may be embedded in the housing's slick plastic lining, and a dab of SRAM GripShift Jonnisnot lube (following a thouough cleaning) on the inner wire would reduce the friction to the nano-scale level I think.

I liked the idea of the set-screw though, because I was thinking along those lines as I read the entire thread. The groove in the tip was brilliant, I didn't think of that, but LocTite would also work.

The newer coil springs in Shimano's derailers were/are actually used to make the cable tension more constant across the entire throw of the derailer, not that I don't like a good conspiracy plot though. I used aftermarket stiffer springs in a couple of the mid-1990's Shimano mech's that had weakened springs, and at least the coil-type springs could be replaced (with admittedly some difficulty) without taking apart the parallelogram.

There is almost always room for improvement in the cabling, such that a reduced amount of spring tension is needed.


Hang a pulley firmly behind the derailleur and run the cable directly from the shifter to the pulley, without any housing.

;) ;) ;)

Hang a pulley firmly behind the derailleur and run the cable directly from the shifter to the pulley, without any housing.

;) ;) ;)

Heh, yeah, you've got me wondering now, still haven't seen a photo of what's going on back there!

Heh, yeah, you've got me wondering now, still haven't seen a photo of what's going on back there!
I found a fix, even if it is a kludge.

Since you asked for pics...

First, two "before" pics:

http://users.rcn.com/jimmuller/pics/CycloneProblem/from_the_side.jpg

http://users.rcn.com/jimmuller/pics/CycloneProblem/from_the_rear.jpg

You can see how the insertion angle of the housing into the RD makes the housing need to go outward around the seat stay, then bend inward and back out again. The side shot also shows a bit of vertical angle where the cable leaves the chain stay. The housing is longer than I'd normally use, but the Jagwire derailleur housing is so stiff that a shorter cable requires an even tighter vertical bend on the back end and a poorer angle where it enters the derailleur. Maybe I should replace it with brake cable housing.

That insertion point on the parallelogram plate instead of the knuckle is clever. It makes the housing rotate around as the parallelogram angle changes so that the cable itself never gets much of a bend. But it means the housing has to make the bend. Suntour probably never anticipated Jagwire, and Jagwire probably didn't consider the Cyclone either.

I "fixed" it by taking advantage of the eyelet. A screw in the eyelet, with the housing routed underneath, pulls the housing in toward the DO and keeps it lower. The screw is locked in place by a nut inside the DO. This seems to have solved the problem for now without any additional surgery required. If necessary I may be able to wedge a shim under the spring inside the parallelogram, but that can wait.

http://users.rcn.com/jimmuller/pics/CycloneProblem/the_fix.jpg

Thanks for everyone's suggestions!

And now I'm wondering if I could route the housing inside the seat stay, whether it would rub the chain or whether angles would be better. I've never routed one this way. Don't tell me, you all do it that way, right?

Jim, glad you got your RD to work. I would not route the cable inside the stay. I don't think you'll have enough room back there with the chain in the highest gears. Plus, personally, I would worry it may start to droop and then cause a jam back there.


I fixed my old suntour deraileur - your spring is not worn out, it is just a design flaw. I could never get mine to drop into the smallest cog from day one. What I did was was drill a hole in the derailleur body directly over the end of the spring. Then I threaded a machine screw in to "pre tension" the return spring. I etched a slot on the end of of the screw with a dremel tool to engage with the return spring, effectively locking it in place at any tension. Worked like a charm,

A clever fix! I, too, have a Cyclone RD with a "worn out" spring. I already cannablized it for spare parts, but it may be worth a repair attempt.

Btw, you must hold the record for longest tenure with the fewest number of posts: Almost a 10-year member and only 8 posts! Don't be such a stranger! ;)

I am almost surprised that the little bit of angling out of the chainstay housing stop was making the cable noticeably sluggish.

I have in the past attempted an improvement by using a tiny zip tie just behind the housing stop, which held the housing more parallel to the chainstay right there. I noticed that this technique seemed to have less of a sharp bend in the housing as compared to holding the housing downward back at the dropout, fwiw.

It's amazing how much that lined cable housing and modern chain, alone, can improve an old bike's shifting.
Now it's not too hard to have a friction-shifted bike that shifts better than they ever did back in the day.
That's enough reason for a resurgence of friction shifting as far as I'm concerned.

Now enjoy that snappy Cyclone shifting action! You've earned it. And you're right about the old Suntour's cable entry into the derailer, those derailers ARE noticeably smooth for a reason.

And now I'm heading out on my last-minutes evening commute hill ride, friction shifting (Simplex, 5sp Uniglide, 9sp chain, lined housing) of course!
Oh, and I forgot the 350-Lumen headlight, SPD pedals and fine clinchers.
Good times, these.
Old bikes rule.

I am almost surprised that the little bit of angling out of the chainstay housing stop was making the cable noticeably sluggish.
I'm not sure the angle at the chain stay caused the problem. Pushing the housing around the DO by hand made a difference even without me lowering the cable. I think the main reason the derailleur wouldn't shift all the way is that the housing puts a torque on the parallelogram.

But I'm glad I found an easy fix!

I see what you're saying now, it kind of reminds me of how a stiff cable housing can also mess with a derailer's B-tension position, requiring the screw to be backed all the way out.

Jim,

I have a pair of pannier/bag hooks that attach at the eyelets and are used as a quick "tie down" to secure bags. One can barely be seen in this picture. It sort of blends in with the aluminum stay for the rack. One would hold the RD cable housing nicely. I'll send you a set.

http://i125.photobucket.com/albums/p71/pastorbobnlnh/Super%20Sports/Sports%20Tourer/P4070006.jpg

I'm actually going to try this trick. The pictured RD (Shimano LeTour) does not like to go onto the small cog of the freewheel. I also have this challenge with my '71 Paramount which runs a Sachs-Huret Eco DuoPar RD. :thumb: Thanks for solving this!

Looking again at your photo, I wonder if you can now shorten your RD housing? Although I'd be inclined to leave well enough alone if it works well now. :)

I have a pair of pannier/bag hooks that attach at the eyelets and are used as a quick "tie down" to secure bags... I'll send you a set.
...
Looking again at your photo, I wonder if you can now shorten your RD housing? Although I'd be inclined to leave well enough alone if it works well now. :)
Hi, Bob. Thanks for the offer. At this point in time, or of you prefer, right now, sending me pannier hooks isn't necessary. I have various thingies like that but I don't know that I need them.

Are the housing and cable too long? Rigged as shown they probably are. I'm really thinking I should replace the housing with black Jagwire brake housing, since it isn't as stiff and takes a set more easily. Then I can bend around the DP and back out toward the DR insertion hole.

Your derailleur as shown is set up much less horizontal than mine, so the sweeping vertical bend at the rear of the cable isn't nearly as sharp. But you do have an angle where it comes off the stop on the stay. Drop me some email as to how it works out.

Stay warm!

I'm not sure the angle at the chain stay caused the problem. Pushing the housing around the DO by hand made a difference even without me lowering the cable. I think the main reason the derailleur wouldn't shift all the way is that the housing puts a torque on the parallelogram.

But I'm glad I found an easy fix!

Jim, I would think that the housing position isn't putting torque on the parallelogram, but rather torque about the hanger pivot axis. The new routing is increasing the torque that axis, increasing the "B-tension". This puts the upper guide pulley closer to the cogs, making that last shift onto the smallest cog easier.


I see what you're saying now, it kind of reminds me of how a stiff cable housing can also mess with a derailer's B-tension position.

Yes, this exactly. I think this is what the new housing routing is doing, and I think this is what's aiding the shift to the smallest cog.

Jim, I would think that the housing position isn't putting torque on the parallelogram, but rather torque about the hanger pivot axis.
In point of fact, or if you prefer, in fact(*) you are quite right that it affects the hanger pivot too. That's why I ended with such a long piece. When it was conventionally shorter it did affect the B angle. But the chain pulls the derailleur forward against the stop anyway.

That Jagwire derailleur housing is VERY VERY VERY stiff. Giving it a permanent bend, or a non-permanent tight bend, is non-trivial.

* - Sorry. There's a thread in 50+ right now about over-used and mis-used words. Maybe I shouldn't go there.

In point of fact, or if you prefer, in fact(*) you are quite right that it affects the hanger pivot too. That's why I ended with such a long piece. When it was conventionally shorter it did affect the B angle. But the chain pulls the derailleur forward against the stop anyway.

That Jagwire derailleur housing is VERY VERY VERY stiff. Giving it a permanent bend, or a non-permanent tight bend, is non-trivial.

* - Sorry. There's a thread in 50+ right now about over-used and mis-used words. Maybe I shouldn't go there.

The late great Sheldon had a nice tip for pre-bending SIS derailleur housing-- pre-bend a piece that is slightly longer than needed before making the final end cuts. The bending will distort the ends (as you pointed out). Then trim the ends flat with whatever tool you normally use to cut housing (I use a dremel-type rotary tool with a cutting disc).

Btw, you must hold the record for longest tenure with the fewest number of posts: Almost a 10-year member and only 8 posts! Don't be such a stranger! ;)

I was thinking that could be some kind of record. I'm happy I've got the same email address and could get my password.

washer between derailleur and dropout hanger.

Alternatively, depending on how much of a spacer you have on the non-drive side of your hub, swap in a smaller spacer there to move the whole wheel a bit to the left, and an equivalently larger spacer on the drive side.

I did this once when I had the same problem as the OP and happened to notice the spacers were of different thicknesses (the fatter one being on the non-drive side.)

Since this thread got bumped by someone else, I post a final report. I ended up using a piece of brake housing. It worked like a charm. That Jagwire derailleur housing is just too stiff.

Wow, who'd thunk it?

Great solutions. In many cases where a spring it too weak, and can't be replaced,
you can fool the spring into being stronger. (Give it less to do).

ftwelder's suggestion fools the spring into less travel, but at higher compression. Your solution likely changed the pressure on the "fore-aft" swing of the RD, making the spring better able to handle an opposite force. I was going to suggest putting some kind of block at one end of the spring to compress it a bit.

I'm also thinking that combining your cable factor fix with ftwelder's suggestion, and also changing the compression on the spring may be a fix for as long as you last, or the bike does, whichever is most appropriate.

Since this thread got bumped by someone else, I post a final report. I ended up using a piece of brake housing. It worked like a charm. That Jagwire derailleur housing is just too stiff.

I had this problem once, on a indexed RD & I used a piece of Suntour SS spring type Derailleur housing. It has a tight enough wound that it doesn't compress in such a small section that it worked perfect.

Glenn

Good input from everyone. I did consider putting a shim under the spring inside the parallelogram, decided that since I already had small sections of brake housing that solution required less work.

In case it isn't obvious, the key to this issue for me can be seen in the second picture above. On the Cyclone 1 the housing fits into a tight hole in the back of the inner parallelogram plate. Being part of the swinging plate its angle w.r.t. the bike frame changes as the parallelogram swings. This means the cable always emerges straight out of the housing with no bend, one reason it shifts so smoothly. But it means the derailleur end of the housing must bend around laterally to be pointing outward as well as forward, and more outward in the higher gears. The stiffness of the housing not wanting to bend was torquing the parallelogram toward straight forward. A more flexible housing reduced this torque, plus I was more able to give it a permanent lateral bend.