Medium of Long Cage??

[grizzly]

I’m in the process of building up a Trek Fuel OCLV frameset, and am trying to work the bugs out. I’ve decided I need a new drivetrain, and looking at deraileurs, I noticed that Shimano has XT medium and long cage to choose from.

I guess first, what would be the benefit of either and if you had to choose one for a full suspension bike which one would you choose?

I’m new to this forum, and am trying to spend more time in the saddle. I used to be a +150 miles a week kind of guy, but then I got a real job and my bike took a side seat. I thought if I built a new bike I would rekindle some interest and to be honest, I feel like a kid again!

Any information would be appreciated.

Griz

[cjm]

Welcome Griz.

The length of the cage of a rear changer should be set roughly according the change in size of both chain rings and cogs on the cassette. So, on a Downhill race bike with a single ring and what would normally be considered a road cassette, we can use short cage rear changer. On an XC race bike with three rings and say and 11-34 tooth range on the cassette, you would probably need a long change. If you tell us your gear range someone on here might be able to tell you exactly what to run. A simpler to follow, rule of thumb, is one ring gets a short cage, two rings get a medium cage and three rings get a long cage.

My experience, is that the most noticeable difference is, that the shorter you go, the less trail damage your changer takes. Next would probably be weight reduction, if you notice stuff like that. You’re dropping weight in both the changer and the chain since you use fewer links. Also, if you are dropping your chain or dealing with a lot of chain slap, it might help with that.

Hope this helps.

[grizzly]

Thanks for the info CJM. I’m running an 11-34 cassette with a 22/32/44 on the front. I would imagine from what you told me, I should probably get a long cage. I’ve also got my a XT top swing deraileur on order so hopefully the new gear will mesh.

[Corey Maddocks ✓ supporter]

I have a Giant Trance full suspension bike with that exact gear setup and I use a Shimano XTR long cage, rapid rise rear derailleur. It works great.

By "top swing" XT, I assume you mean the front derailleur. If so, the issue there is that some full suspension bikes have a shock mount that does not leave room for a bottom-swing, or standard, front derailleur, and a top swing is required. This is the case for mine, and I have a Shimano XT top swing and it fits, and works like a dream.

Here’s a bottom swing front derailleur:

And a top swing:

Hope this helps!

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