Replacement derailleur for Shimano SIS - 7 speed

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Replacement derailleur for Shimano SIS - 7 speed

Postby three_jeeps » Tue Mar 22, 2011 12:27 pm

My son's bike is an older Schwinn Moab mountain bike outfitted with Shimano grip shift shifters and Shimano SIS derailleur (7 speed rear, 3 speed front).

The rear cage got severely mangled and I need to replace the entire derailleur. I am guessing it is a 'medium' length but not sure. The hanger is part of the bike frame (no removable hanger, no removable dropdown)

So my questions are:
1. Where on line can I get an exact replacement (if possible - bike is about 6-8 yrs old.)

2. Given the cost of the bike, I am guessing this is a fairly low grade derailleur...what would be a reasonable upgrade to replace just the derailleur? I am guessing the original cost between $15-20 USD....Maybe something around $30-40?

3) If I got an upgrade, what features would it have or enhance over the stock derailleur?
For example, would it make the gear changes snappier? Less chain bounce when changing, etc.

One thing I noticed is that it seemed to require constant periodic short term adjustments. It seemed that after 3-4 days on the trails, had to adjust hi/lo limits...

Thanks for your help.
-John
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Re: Replacement derailleur for Shimano SIS - 7 speed

Postby maddslacker » Tue Mar 22, 2011 6:57 pm

Check with your LBS. I had the same issue on my daughter's 6spd a couple summers ago and they got me a direct replacement for like $12.
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Re: Replacement derailleur for Shimano SIS - 7 speed

Postby three_jeeps » Tue Mar 22, 2011 10:27 pm

ty.....hmmm..LBS?

I didn't want to go that route....that is why I asked the question here.

The LBS around me are known for gouging ppl on price, and their tech work is sloppy and inattentive. I have more than enough mechanical knowhow to replace and adjust a derailleur...just need a lil guidance on getting the right one....

Besides, its a bike, not a rockeship...
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Re: Replacement derailleur for Shimano SIS - 7 speed

Postby maddslacker » Tue Mar 22, 2011 10:30 pm

Well yeah, I installed it myself, they just sold it to me.

Check JensonUSA online. They stock a lot of 'oem' type parts too.
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Re: Replacement derailleur for Shimano SIS - 7 speed

Postby ltud » Wed Mar 23, 2011 7:35 am

I just had a similar problem on my girlfriend's son's bike. I couldn't find anything that fit for a less than what we paid for the bike, so I ended up repairing the derailleur.
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Re: Replacement derailleur for Shimano SIS - 7 speed

Postby bhuber » Wed Mar 23, 2011 11:28 am

is there a serial or part # on the derailleur? if so just search it on google or even ebay. i just did a quick search of shimano sis derailleur on ebay and found a bunch for around $15, but there was a lot of different models, so you would need a model # or even just go by the pictures.

or just turn it into a single speed.
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Re: Replacement derailleur for Shimano SIS - 7 speed

Postby three_jeeps » Wed Mar 23, 2011 11:36 am

bhuber wrote:is there a serial or part # on the derailleur? if so just search it on google or even ebay. i just did a quick search of shimano sis derailleur on ebay and found a bunch for around $15, but there was a lot of different models, so you would need a model # or even just go by the pictures.

or just turn it into a single speed.


Thank you...I did that before I posted...I looked over the derailleur and could not find a number (are they in a not very obvious place?)

Another thing that is not clear to me is the categorization of 'short', 'medium,' and 'long' cages...
It would seem logical that there are some sort of dimensions associated with them but I have not been able to find them. My derailleur is not short, but might be considered medium or long, so how do I know?

-J
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Re: Replacement derailleur for Shimano SIS - 7 speed

Postby maddslacker » Wed Mar 23, 2011 11:38 am

Come chat about mountain bikes in real time!
http://gotslack.freeshell.org/mtb

carpe tracto talea
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Re: Replacement derailleur for Shimano SIS - 7 speed

Postby maddslacker » Wed Mar 23, 2011 11:45 am

three_jeeps wrote:Thank you...I did that before I posted...I looked over the derailleur and could not find a number (are they in a not very obvious place?)

It's usually just a model number and is frequently long since worn off.

Another thing that is not clear to me is the categorization of 'short', 'medium,' and 'long' cages...
It would seem logical that there are some sort of dimensions associated with them but I have not been able to find them. My derailleur is not short, but might be considered medium or long, so how do I know?

The length of the cage determines how much chain slack the derailleur can absorb and therefore how many total gears it can span. For a kid's 21 spd, a mid cage should be fine, maybe even a short cage.

Again, take the old derailleur to an LBS, they will stock an OEM replacement, probably for under $20. Pay, say thank you, take it home and install it. If they want more than $20 for a stock 7 spd model, feel free to swear at them and throw stuff around the shop.
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