alij2018

Hi, I am planning to upgrade my mountain bike to 10 speeds soon. I want to know if I need a long cage or medium cage rear derailleur as I am confused. Here are the details of my specs:

-Shimano Deore M6000 derailleur.
-Cassette 11-42T
-1x chain ring 30T

So, what I need, a SGS or GS rear derailleur?

Thanks

shelbyfv

You should post the relevant specs for the two choices.

fietsbob

SGS Is good for 34, maybe 36, not 42.. in a standard build,,..

there are widgets moving the mounting tab downward you add those to push capacity

but not chain wrap.. need a lot? go long..














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alij2018

What specs do you need? I already stated.

alij2018

Drivetrain same as Cannondale Trail 5. 11-42T rear and 30T front. What I need?

canklecat

When in doubt, I'd say go for long cage -- that's the SGS version. That's the version on the Cannondale Trail 5 with the 30T chainring and 11-42 cassette.

I use long cage on my bikes with cogs up to 32T, but these are older 1990s Shimano Exage 500CX, and Deore LX SGS. The Deore is a little better. And I use triples, 30/40/50. No problems with covering the full range, even crosschaining to 50 front/32 rear (just as a test to be sure I don't rip the derailleur off, not a gear combo I actually use).

I even used the early 1990s Deore LX SGS on a road bike with 13-28 freewheel for a month. Worked great. I just replaced it with a 1990s Shimano 600 short cage, but that's mostly for appearance so the big kids don't tease me at group rides for having a mountain bike derailleur on a road bike. Kidding, I'm 61 and don't care what people say. I just wanted to try a short cage RD. No difference in function.

Check the mountain bike forum for suggestions on other derailleurs. They'll have more practical info. I'm just a casual gravel rider. The Deore is a good value but MicroShift and others may be as good or better.

alij2018

You confirmed that the Cannondale Trail 5 2019 with 11-42T rear and single 30T front uses SGS? And me too I need to get the same SGS? Thanks

fietsbob

42 - 11 = 31 that is wrap .. the RD has to clear the biggest cog, that is capacity..
with only one chain ring ..

if you had 2 chainrings you would add the difference between them to wrap demand..

Retro Grouch 

I can see why you decided to ask. I just looked up the Shimano docs and, the answers are there, but they're not as obvious to find as I think they should be.

1. Largest cog size - 46 teeth. You're good.
2. Chain wrap up. You have only 1 chainring so your wrap up needs are modest. GS cage length is fine.

alij2018

So, I need to get GS?

alij2018

So, GS is fine for me then?

canklecat

GS would work with a single 30T chainring, but I'd still go for the long cage SGS. The only downside to a long cage might be snagging debris -- twigs, long tough grass, etc. That might be an issue for some hardcore off roaders in some terrain. But I'd still prefer the long cage. It's more versatile.

The only time I've had anything snag in my rear derailleur was when wind from a sudden storm front blew a plastic bag into my RD. It's pretty rare. Wouldn't deter me from using a long cage RD.

fietsbob

Find and quote the data for Cap and Wrap of both .. your job, your question..

for the 11-42t cassette you likely need one of these:

https://www.wolftoothcomponents.com/...ducts/roadlink
to move the whole RD mount Down.

1 chainring it does not matter , just a bigger one needs more chain to go around big-big pair.

restricting your cassette to only 30t and having just 1 chain ring
then a shorter cage, less slack wtap, would probably work..

I'm just not into the latest 1 by stuff..










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