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Medium cage derailleur for 20" kid's bike?

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Ferg_S

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Discussion starter · #1 ·
My son has bashed his rear derailleur on his little Orbea. Not surprising given the way the cage runs so close to the ground. It's a Shimano Altus M2000 SGS Shadow and the rear cassette is 11-36T 9-speed. Are there any short or medium cage derailleurs that would also work, to get a bit more ground clearance? I'm totally ignorant of it all, as I've not broken or replaced anything since about 2005. :D I don't mind going up a few product lines if it helps, but I think then it mostly gets into 10-speed drivetrains and maybe that's not compatible with the 9-speed rear?

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#2 ·
If you look for older (pre-10 speed) derailleurs, you can find medium and short cage variations. I have seen medium and short cage in both the XT and XTR varieties.... maybe LX had them too?
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Prior to 10 speed, all those older 7, 8, 9 speed derailleurs were cross compatible with 7, 8, 9 speed shifters, so in theory they should work with your existing Altus shifter. Road derailleurs would also work with the shifter, the exception being that the cages won't work with the larger cassette.

You could also look at changing to the Microshift Advent Super Short drivetrain setup which was designed for 20" wheel bikes (I've used this on a Surly Pugsley with great results.)
 
#5 ·
Ferg_S said:
Thanks, lots on local auction sites. Can a short cage handle the 11 - 36 spread and have enough spacing on the top pulley for the 36? Asking as I don't really know.
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Here is a link to the XTR 952 derailleur that had the 2 different cage lengths XTR 952 Manual
It suggests that both derailleurs are capable of going to 34T max rear sprocket (but I've run 36T with no issues) and that the extra length in the cage was more to take up larger gaps in the triple front chainrings. Since you have a 1x system, it should work.

I linked the XTR because that was the first one I found, but I imagine that data would transfer over well to many other short cage (shimano) derailleurs at least.
 
Discussion starter · #6 ·
Thanks for the tips, I'll get shopping around.

Yes, that's the stock rear derailleur, the picture is from a review of the bike. The MicroShift Super Short stuff is interesting, but quite pricey and difficult to get over here. As I understand it, it also only works with the matching shifter, maybe also the cassette?
 
#7 ·
Ferg_S said:
Thanks for the tips, I'll get shopping around.

Yes, that's the stock rear derailleur, the picture is from a review of the bike. The MicroShift Super Short stuff is interesting, but quite pricey and difficult to get over here. As I understand it, it also only works with the matching shifter, maybe also the cassette?
Click to expand...
Yeah, as best I understand the Advent/Advent X product lines, they are a system so you would want to keep shifter/derailleur (at minimum) paired up. Advent Thread may have actual numbers/info on if people have "swapped" parts on it.

Occasionally I have had items sell on ebay that end up going internationally, not sure how that works on the buyer-end with costs and what not, but that could be an option?
 
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