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SamuraiBunnyGuy
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Discussion Starter · #1 ·
now that i have dumped my large chainring for a bash and am only running with 22/32 up front, can i safely replace my long-cage rear derailleur with a mid-cage since it wont need to extend so far forward to handle the 44 ring? or is cage length more dependent on the size of the largest cog in the cassette (running 11-34)

ill be ordering an XT-M772 9-speed, my stock one from 3 years ago is beat to shyte

holy crap jenson has the exact SLX front derailleur i need on clearance for only $8
 

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SamuraiBunnyGuy
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Discussion Starter · #3 ·
woohooo looks like i picked the right time to be shopping for 9-speed replacement components.
+ new SLX shifter set for only 38$,,,
 

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I'm running a triple with bash and 22/32 chainrings too, but with an 11-36 cassette. I recently switched to a mid cage rear derailleur--even though technically the 32/36 combo isn't correct for that derailleur. When I installed the new Shimano 10 speed mid cage derailleur, I used the same length chain as with my triple derailleur, and I was surprised to see that the big-big combo did not have the derailleur very stretched out ( it looked like it was at about a 45 degree angle), so I thought it was fine. Yesterday, I went off a 12 inch drop, and the rear of my bike exploded.

When I extracted my rear derailleur from the spokes, I discovered the cage with the pulley wheels, which is normally straight, was bent at a 90 degree angle. The chain was jammed between the spokes and the (new) cassette so bad, it took a lot of jerking and pulling to finally free it. Needless to say, all my drive side spokes were ruined. I removed the chain and derailleur, and then I walked 1.5 hours back to the TH. I wasn't able to determine definitively whether I was in big-big, although after I removed the derailleur, I released 8 clicks from the rear shifter before it bottomed out, which suggested I was not in big-big.

I just installed a new long cage Shimano derailleur, new chain, new derailleur hanger, and eight new drive side spokes. I was never able to get the mid cage derailleur adjusted properly, so I thought the shifting was terrible. If I adjusted the shifting so the low gears were perfect, then the shifting for the high gears was sluggish, and if I tightened the cable to get the high gears shifting properly, then the low gears would overshift slightly.
 

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Pivotal figure
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You can even run a short cage der if you get the proper version. I have a Zee on my 4X and it works great with the 11-36 cassette.
edit: Whoops! missed that you were still running a 2 ring setup. Gonna need mid cage at least....
 

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I'm running a triple with bash and 22/32 chainrings too, but with an 11-36 cassette. I recently switched to a mid cage rear derailleur--even though technically the 32/36 combo isn't correct for that derailleur. When I installed the new Shimano 10 speed mid cage derailleur, I used the same length chain as with my triple derailleur, and I was surprised to see that the big-big combo did not have the derailleur very stretched out ( it looked like it was at about a 45 degree angle), so I thought it was fine. Yesterday, I went off a 12 inch drop, and the rear of my bike exploded.

When I extracted my rear derailleur from the spokes, I discovered the cage with the pulley wheels, which is normally straight, was bent at a 90 degree angle. The chain was jammed between the spokes and the (new) cassette so bad, it took a lot of jerking and pulling to finally free it. Needless to say, all my drive side spokes were ruined. I removed the chain and derailleur, and then I walked 1.5 hours back to the TH. I wasn't able to determine definitively whether I was in big-big, although after I removed the derailleur, I released 8 clicks from the rear shifter before it bottomed out, which suggested I was not in big-big.

I just installed a new long cage Shimano derailleur, new chain, new derailleur hanger, and eight new drive side spokes. I was never able to get the mid cage derailleur adjusted properly, so I thought the shifting was terrible. If I adjusted the shifting so the low gears were perfect, then the shifting for the high gears was sluggish, and if I tightened the cable to get the high gears shifting properly, then the low gears would overshift slightly.
It wasn't the dereilleur, your chain was too short. The length of the cage has nothing to do with the big cogs, it is there to take up the slack in the little cogs. Chain must be sized to the big big combo, plus usually around four links. Might need to be more if you are on a suspension bike that has a lot of chain growth. The best way to check chain length is to let all the air out of the shock and bottom the suspension. If the bike runs out of chain before it bottoms, you have issues. Start with too long of a chain, check it, and take out links if necessary. It's hard to put links back in correctly.
If you run a derailleur with too small of a cage, all that will happen is your chain will be slack in the small small combos. Since you shouldn't be in that gear combo anyway, its not so much a big deal.
 

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In the rear with the beer
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Should not be a problem at all. But to double check I believe you can see specs on shimanos website for their parts and it will tell you what the max teeth combo is for each derailleur.
 

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or is cage length more dependent on the size of the largest cog in the cassette (running 11-34)
The RD has to have enough capacity to handle the difference between the biggest and smallest combinations in your drive train as a whole. Doesn't matter if the difference is made in the front (chainrings) or rear (cassette).

In your case it's (34-11)+(32-22)=33. Look for a derailleur with a capacity of 33 teeth, no less.
 

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SamuraiBunnyGuy
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Discussion Starter · #9 ·
the found a site with the 772 mid-cage specs, and the numbers match my drivetrain perfectly. thanks

Maximum Sprocket 34T
Minimum Sprocket 11T
Front Difference 22T maximum
Total Capacity 33T

and woohoo i just finished my taxes
 

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It wasn't the dereilleur, your chain was too short.
I don't think it was.

The best way to check chain length is to let all the air out of the shock and bottom the suspension.
Yep, I removed my shock to bottom out the suspension, then I did this:

1. Remove the old chain.

2. Shift the front derailleur over the largest chainring, and the rear derailleur on the smallest cog.

3. Thread the new chain through the front derailleur. It is not necessary to thread the chain through the rear derailleur at this point. Simply wrap the chain around the largest front chainring and around the largest rear cog.

4. Pull the chain tight, and note the closest rivet where the two could be joined. Keep in mind a chain can only be joined by mating inner and outer plates.

5. From the closet rivet, lengthen the chain by counting over an additional two rivets (two links), which is a distance of one-inch. Cut the chain at this point.

6. Remove the chain from the bike and thread it through both derailleurs and join the ends.

(ref: Park Tool)
If you run a derailleur with too small of a cage, all that will happen is your chain will be slack in the small small combos.
That makes sense.

The next day I blew up another new, long cage derailleur when it hit a rock. More spoke replacement, another new derailleur hanger, etc.

In my first year of mtb'ing, I never bent a derailleur hanger , and I crashed every ride for the first three months, then weekly for the next three months. Now, I rarely crash and in the last two weeks, I've bent or broken 4 hangers, 2 derailleurs, and lots of spokes. Sheesh!

In any case, I hated the way the medium cage shifted. The light action shifting of my XTR shifters disappeared, and each shift made a huge thunk, and I could never get the derailleur adjusted to my satisfaction.

Currently, I'm running a used, long cage, XT derailleur whose plastic clutch broke off, and this particular derailleur likes to snap derailleur cables a long way from the trailhead. I broke two cables in a month while the clutch was on, so I stopped using the clutch, then I noticed the lever had broken off.
 
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