La Brea Bike

Does anyone have a favorite way to increase spring tension to compensate for a weak rear derailleur upshift to high gear? I see numerous bikes that have been stored long term in a low gear... Thanks.

DiabloScott

You might be able to disassemble it and put one more twist on the coil spring.

cxwrench

That's some funny **** right there. And for the OP, springs don't 'wear out' from sitting around un-used. Go ask this question (or the firearms version of it) at a gun forum and check the answers. Do magazine springs wear out if you leave mags loaded? No.

La Brea Bike

Funny, those are the ones that tend to have the problems with spring tension. Must be a coincidence. Thanks for the helpful comment. Often zero witness marks on them. Please enlighten us as to why they lose tension when they have been left in that position.

jonathanf2

If you don't mine doing the work yourself, drilling a hole on the RD cage might be a way to help increase tension. I would just position the hole slightly above the highest tension hole on the cage. If you do a Youtube search, I believe there are videos demonstrating this procedure. Good luck!

cxwrench

How do springs wear out?

Andrew R Stewart 

I believe that the OP is talking about the parallelogram return spring and not the cage pivot one. BTW when the cage pivot spring tension is played with on ders with a sprung hanger mount pivot spring ("B" pivot) that B spring also will want tension changes. The cage (the rarely mentioned "A" spring) spring and the B spring have a tension relationship to establish a good guide pulley and cog underside gap.

Back in the 1980s/1990s Shimano did offer a few ders with an adjustable parallelogram return spring tension. They had a cam that one end of the spring was acting on and by rotating that cam the spring end could be raised or lowered WRT the parallelogram link. I took this as an admission that MtB cables would get gritty with mud/dirt and stop moving as freely as they do when clean.

Early in on Shimano's development of their indexed systems was the goal of reducing the effort to move the shift lever. The rear der parallelogram return springs were softened in their strength and their STI lever had a helper spring move the cable spool. The cable was being, sort of, pushed as well as pulled.

I have commented on rear ders losing the ability to pull the cable enough to allow shifting into the smallest cogs. Many here have replied that springs don't lose their tension if they haven't been stretched beyond their designed movement range. (Unlike a canit brake arm return spring and how one can over rotate the arm to change the spring's willingness to act on the arm, and help center the brake pads WRT the rim). My experience with older Shimano MtB rear ders suggest something is happening to reduce the der's willingness to shift into those hi gears. A simple test is to detach the cable from the der and shift the system by pushing directly on the der. Release the der and watch it shift all the way down the cog set. Reattach the cable and watch the der get hung up due to the cable friction. Sometimes replacing the cable and that last loop of casing running to the der is enough to get acceptable performance. Sometimes not and a replacement der is called for. Andy

smd4

Having disassembled multiple Shimano rear derailleurs, I think it would be pretty much impossible to rotate the spring "one more twist." Unless you're Popeye, perhaps.

In my derailleurs, I don't think there's any way whatsoever to increase the tension on the parallelogram spring--it's a coil spring with no way to adjust it.

KerryIrons

Springs don't "wear out" or weaken unless they have been overstretched. Your most likely problem will be solved by cleaning and lubing the derailleur. Fully disassemble it, wipe everything clean, and reassemble with grease/oil in all the metal to metal contact surfaces.

John Valuk

I appreciate your thoughtful comments on this.

A couple of years back, I woke my 1995 Trek 730 Multitrack from a long slumber, and started putting some miles on it. Several thousand miles later, I was having trouble with the rear der (Alivio) not reliably shifting into the smallest cogs. It seemed that the behavior was tied to the der itself, and not to cable/housing/shifter. Moving it directly by hand, the motion of the parallelogram did not feel rough or sticky, so it gave me the impression of "weak spring".

I replaced it with a used-but-clean der of similar type/vintage, and I was back in business.

I haven't discarded the one that was giving trouble, and have sort of kicked around the idea of trying to identify a replacement spring to try in it.

Iride01 

How do you determine that these bikes you see are actually suffering from the supposed effects of long term storage in low gear? And that it's a weak spring, instead of just a gummed up lube from sitting many years or is just dirty and needs cleaning or the cable is binding from corrosion or old lube?

And are you wanting to fix all these old bike like this that you see? Or is this a hypothetical situation for our debate and amusement?

Sal Bandini

I also have a poorly shifting Alivio 9 speed. It was suggested that I change the cable and housing, but before I did that, I checked the other bikes. My son has the same der and the difference in spring tension is noticeable. I would say it is about twice as hard to move the der. My daughter's cheap and older Trek even has more tension. Swapping the cable doesn't seem to make sense if the spring appears to be the problem.

I opened up the der assuming something was broken or it was in a different spring hole. Apparently some of the der have multiple holes but mine didn't. Everything looked fine. Even at the reduced spring tension mine had it was extremely difficult to reassemble. That spring has a lot of tension!

I am glad that a swap worked for you, as that is what I plan on doing. I just need to decide if I replace it with another Alivio or older Deore.

BCRider

I've yet to see a derailleur that has a weak return spring. If they are not able to snap sharply against the limit screw then something is wrong that needs attention.

It might have been suggested already in one of the replies. I only skimmed over them. But the first step is to isolate the derailleur from the cable and shifter. Remove the chain so it doesn't snag and disconnect the cable from the derailleur. Check to see if it moves easily and with force. If it doesn't there's grunge or corrosion in the link pins. WD40 and some cycling of the pivots should free them up. But if that doesn't do the trick I'd wash it well in a water based degreaser to clean away the oils then soak it in Evaporust for a few hours. To encourage the rust remover into the pivots work the cage fairly frequently during the soak. Ideally while immersed. Evaporust isn't harmful to us as far as I know if washed away promptly. But a set of gloves wouldn't hurt. After that rinse well, dry well and oil. At that point it should snap to the return position like a new bear trap. If not then I'd say it's time for a new derailleur.

If the deralleur works with a mighty snap for the return with no sticky points then the issue must be in the cable and housings or in the shifter. You can isolate the cable setup from the shifter by pulling the housing end out of the shifter body an inch or two. Between pulling on the free end which will push the housing back into the shifter and pulling teh housing back out again it should be easy to determine if the cable is sticking or not. The cable will wear a groove into the housing liner over time. And if that groove is deep it can grab the cable pretty strongly. The answer is new housings and free play should be restored.

If it's not the housings then all that is left is the shifter itself. It may be grunged up or it may have been damaged at some point in a way that is causing it to bind. With the cable moving freely check to see if you can pull on the derailleur end of the cable and operate the shifter and that it moves cleanly and with a nice snap of the cable when shifting to releasing cable.

Somewhere in these three checks you are going to find the source of the binding.

John Valuk

Mine is from the time when Alivio was 7-speed. I had been keeping an eye out for new old stock and used-but-clean components on eBay, and buying when the right deals turned up, so I already had a spare on hand.

I'm sure that there are a number of options for replacement with higher-end vintage components, but I've never educated myself enough about it to know what to be looking for, or what reasonable prices for them would be.

SoSmellyAir

I generally agree with this concept, but then I also observe how new springs installed in a car settle and slightly lower the ride height after a certain period of time and number of miles. This phenomenon happens for OEM, OEM+, and aftermarket springs, regardless of whether the same dampers are retained or new dampers are installed.

cxwrench

Cars have much higher spring rates and these things called dampers. That's a spring settling not wearing out.

pdlamb

So really big car springs with really big loads take a set, but you're saying (comparatively) tiny derailer springs with tiny loads don't take a set ... because ?

FWIW I've not seen a viable prediction of when a spring will take a set (or, if you want to get technical about it the spring "constant" will change) that doesn't involve permanent deformation. You bend it, the spring changes. If you don't but store it compressed (or extended) for a long time, some will change, some won't.

70sSanO

I’m more on the fence with spring creep. I tend to lean toward a properly design, and manufactured, spring that is used within the design range probably won’t have an issue.

I’m not certain that every spring that is massed produced fits neatly into that box. Especially with consumer goods that don’t require material certifications.

I also think that automobile springs are a bad example in that over-compression can impact the life of the spring. Too much weight, too many potholes probably have an adverse effect.

John

Edit added: I also don’t know if the number of anticipated cycles impacts the design when going from Tourney to XTR.

Troul 

A rebound spring should provide an exceptional service life if it's designed purpose & rate are accurate. A tension spring (ie: garage door) has a much lower service life expectancy range, & if not maintained (free of grit, cleaned for heavy dust, kept well lubricated) the service life is reduced. If a tension spring is wound to a *hot* tension, it exacerbates its service life too.

La Brea Bike

So, at my bike shop, I am willing to work on anything without judgment. I also have a lot of lower income folks that I try to keep mobile. When I see them drag in a bike that has obviously been in someone's garden or attic, I automatically look at the gear it's been left in. I try not to curse around the kids, but if it's in the granny gear, I know I'm in for trouble. I often swap in a Tourney RD to make them work again, but some of the RD's are in beautiful (aesthetic) shape, and I hate to toss them.

ThermionicScott 

Cleaning the pulleys would be a good thing to try, if you haven't yet. I have one rear derailleur that seems to be sensitive to this -- if the jockey pulley is gunked up it will hesitate to shift in a few of the gears. Cleaning them and applying a very light lube fixes it up.

Andrew R Stewart 

The most common issue I see with guide pulleys and shifting has nothing to do with parallelogram return springs, the pulley's bushing becomes worn enough to develop too much slop/rocking and the amount of over shifting movement of the cage (designed in at the shifter) is insufficient to place the chain under/slightly past the adjacent cog. This rocking is easily mistaken for the end play Shimano guide pulleys are designed with. When the guide pulley flops about it no longer is controlling the chain/cog dance well. This situation has been mentioned in a number of other threads over the years.

How to tell the difference between a parallelogram that has stiff/tight pivots and one that has a soft spring is pretty easy to do. Detach the cable and chain. Push the der inwards to the spokes. If the pivots are so sticky that it hinders the full range of return movement you will feel that added friction as you pushed the der in, the effort will be both the spring (which is assumed to not having lost any tension) and the pivot friction. Go to a few "known good" ders and repeat and you'll quickly feel the differences to push the der inwards and can see the return action. Many ders will develop slop in their pivots (especially those that use stamped and folder steel parallelogram links) which reduce the possibility of a pivot being tight. (While I have worked ders that do have tight pivots they often have a lot of rust/corrosion showing and often will loosen up with "working" the parallelogram, cycling it through its range of movement repeatedly). This is not rocket science.

I have mentioned that Shimano specifically did soften their der return springs way back in the 1980/1990s (and in the good act of marketing called it an improvement). It was about then that I began to see this "too soft spring" problem. My speculation is that Shimano sourced springs that were not up to the usual standards and this only showed after a few years of use. Shimano is well known for using the same small parts on a range of components. I can easily understand if a batch (and for a company the size of Shimano this could be in the order of tens of thousands of springs). Since these springs work fine when the bike is new (remember that the OEM market is the vast majority of the sales Shimano sees) and it will be the LBS that will deal with the wear of use, these springs were installed. Andy

ThermionicScott 

On reflection, I didn't describe my issue very well. It's not the teeth of the pulleys that need cleaning (although that's always good to do), but the bushings inside that make the RD balky if they gum up. My best guess is that the "Centeron" pulley sticks to one side, and aided by the meshing of the chain with the cog it's already on, is enough to hold the RD to one side of its parallelogram pivot slop and prevent the chain from being shifted onto the next cog. Used parts are often more interesting than brand-new ones!

Were those softer RD springs a part of the "light action" deal?

DanseMacabre

Can I say "thank you" for this thread? Thank you

For some time I had trouble shifting. I already replaced a spring in the derailer to have it closer to the cassette cogs, but that didn't help.
And all it needed was a bit of cleaning and lubricating. The spring itself turned out to still be fine. I did notice beforehand that moving the parallelogram by hand gave a lot of friction. I had no clue I was slowly destroying the bushings of the rear derailer.
Just did a ride here this afternoon and now shifting, especially to the small cogs, is noticably better.