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Chain Tension/Rear Derailleur Problem
#1
Hello my name is Rob and I’m new to this forum. My wife and I have two 1986 Schwinn World 10 speed road bikes that we purchased new. Overall they’ve seen very little use and are in great condition. Recently I (we?) have a renewed interest in riding. One reason I haven’t ridden is the freewheel on mine was clogged and I never bothered to figure out what was wrong with it. After doing some research, I managed to fix my bike by lubing the freewheel. On my wife’s bike though, the rear derailleur (Suntour AR) is not tensioning the chain properly. It does not spring back to remove the slack. When it’s in the gear with the largest sprockets (front and back), the chain is ok, but anywhere else, it hangs loose. Is there a way to adjust the spring tension on these? Can these be fixed or is replacement the best option? If so, what options do I have for an old 10 speed? Should I try to locate a Suntour AR from ebay or go with something newer? It has friction (not indexed) shifters. Thanks in advance.
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#2
Hi Rob. Cool name!

I'm 99.9% sure that I know the fix. The bike has sat long enough that all lube in the pivot points has gummed-up or just disappeared. This is not at all uncommon.
Start by disconnecting the cable. If you have the tools, I recommend also breaking the chain and removing the drlr from the bike. The idea is to have the fewest obstacles as you do this.

You want to saturate EVERY pivot on the drlr with a solvent and work it in. In your particular case, especially the Main Pivot. Flex every pivot several times, then flush & flex again. You may want to hang the drlr back on the frame to work the Main Pivot as it has a pretty stiff spring. Do this 10x if you feel the need. It is a royal bummer to put it back together and it is only a "little better". Trust me!

Next, flush the solvent out with something like WD-40. You don't want the solvent to displace the lube you are about to apply.
Let it dry for a few hours and then apply a low-viscosity penetrating lube (WD40 is NOT a lube) to each pivot and work it in. I recommend Tri Flow or Finish Line XC with the green cap from a bike shop. Gun shops may carry Tri Flow or a gun lube made my Hoppe's.

While you have the cable detached, pull it from the housing and clean / lube. Better yet - replace it!

If after re-assembly, you find that it is slow to shift to a higher cog in the smallest 2, your main-spring may have 'taken a set' over the years if the drlr was left in a low gear. I seldom find that to be the case, though. Modern springs (and 1986 is modern) rarely have that problem.

Let us know how you fare!

Rob
Wheelies don't pop themselves. (from a QBP fortune cookie)
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#3
Rob, I like your name too!

Great, I was hoping it was something simple like that. I'll give that a try. What do you recommend for a solvent? Will kerosene work? For a lube, so far I've been using some old 3 in 1 that I have and some Dupont Teflon chain lube that I use on my motorcycle chain. Would those work? I'll pick up some Triflow next time I'm at a bike store. Thanks!

(12-15-2010, 11:15 PM)RobAR Wrote:  Hi Rob. Cool name!

I'm 99.9% sure that I know the fix. The bike has sat long enough that all lube in the pivot points has gummed-up or just disappeared. This is not at all uncommon.
Start by disconnecting the cable. If you have the tools, I recommend also breaking the chain and removing the drlr from the bike. The idea is to have the fewest obstacles as you do this.

You want to saturate EVERY pivot on the drlr with a solvent and work it in. In your particular case, especially the Main Pivot. Flex every pivot several times, then flush & flex again. You may want to hang the drlr back on the frame to work the Main Pivot as it has a pretty stiff spring. Do this 10x if you feel the need. It is a royal bummer to put it back together and it is only a "little better". Trust me!

Next, flush the solvent out with something like WD-40. You don't want the solvent to displace the lube you are about to apply.
Let it dry for a few hours and then apply a low-viscosity penetrating lube (WD40 is NOT a lube) to each pivot and work it in. I recommend Tri Flow or Finish Line XC with the green cap from a bike shop. Gun shops may carry Tri Flow or a gun lube made my Hoppe's.

While you have the cable detached, pull it from the housing and clean / lube. Better yet - replace it!

If after re-assembly, you find that it is slow to shift to a higher cog in the smallest 2, your main-spring may have 'taken a set' over the years if the drlr was left in a low gear. I seldom find that to be the case, though. Modern springs (and 1986 is modern) rarely have that problem.

Let us know how you fare!

Rob
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#4
Tri-flow works well for a all purpose lube. Easy to find about anywhere. Lube every moving part on that derailleur. Works fine on the chain too. Degrease with a environment friendly bicycle degreaser. This you might have to go to a bike shop for or order online from a bicycle retailer. Better to support the local bike shop. Soak or spray that derailleur and work the moving parts back and forth, unleashing the grime. An old toothbrush works well for scrubbing.
Looks like Robs gotcha on the right track.
GO RIDE...
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#5
Well I tried it and it's no better. It was kind of "stiff" so cleaning it definitely loosened things up. The spring action for when it goes away from the bike and back seems fine. The spring action going forward and back to tension the chain though is just limp. It's not stiff at all anymore - it moves forward and back freely. It will go through the gears ok, but when it's on any of the smaller gears, the chain goes slack. Do I have a broken spring?
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#6
I managed to find a NOS (new old stock) Suntour AR derailleur off of ebay and hope to get it on soon.
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#7
Ooops,,, sorry, Rob. I was kinda booked for a while. Christmas and Grandsons kinda go together.
Keep us posted, bro.
Wheelies don't pop themselves. (from a QBP fortune cookie)
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#8
Well you guys were right. When I took the chain off, it was dirty and needed to be cleaned so I decided to soak it in kerosene. While I was at it, I threw the old derailleur in there. I left it in there for a couple of days taking it out and moving things around every now and then. It finally freed up. I've reassembled it and it seems fine. I guess I have a spare Suntour AR which I'm not using right now, but that's ok, I only paid about $11 for it. Thanks!
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