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Old 05-20-12, 12:10 AM   #1
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Drivetrain problems with old Suntour Mountech setup

I'm fixing up an early mountain bike with all original suntour parts and making it into a commuter. I need recommendations for replacing the existing 6-speed freewheel and rear derailleur.

The thumb shifters work great, as does the front derailleur. The rear derailleur however makes a ton of noise in most gears, and it seems to be crooked. I think the noise is the chain hitting the side of the derailleur cage as it enters the pulley. On top of this, the jockey wheel is looking near end of life (pointy teeth) and the two of the six cogs on the freewheel are missing teeth.

So I am wondering if I should replace these two parts and keep the shifters, etc., or ditch the setup for something else. I briefly though about switching to an internal hub, but I'd rather not put too much into this project. What would be a solid but inexpensive replacement for these parts?
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Old 05-20-12, 04:47 AM   #2
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Shift into a gear combination that makes your derailleur arm point straight down. Now look at the derailleur from the back. If it looks like it's pointing toward the wheel (common), that's bad. It should point straight down from that angle too. On a 6-speed I can usually "eyeball" it into alignment. Keep the derailleur in place and clamp a big crescent wrench over the derailleur to bend the hanger back straight. Sometimes I can bend it with just my hands.

Don't be tempted to remove the derailleur before bending the hanger because you might ovalize the derailleur mounting hole. I don't know a cheap, easy way to fix that.

Good luck.
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Old 05-20-12, 10:13 AM   #3
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Some of the Mountech rear derailleurs had an upper pulley design that was almost guaranteed to drop the chain. The only way to fix it is to replace the derailleur. IMO, any long-cage derailleur made in the last 20 years will work far better, and new lower-line Shimano derailleurs are pretty cheap. Since your shifting isn't indexed, your shifters will work with any derailleur.

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Old 05-20-12, 11:15 AM   #4
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They were trying to do a Huret Duopar , the French company's design, at the time, was better.

but at least you probably have non unique dropouts. to mount a new RD onto.
as you replace the whole 2 decade + old drive train.

Last edited by fietsbob; 05-20-12 at 11:19 AM.
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