chain dropping of sramxx crank

[George Nel]

Hi,

Did the Attakwas and dropped my chain 5 times in the first 40km,irritating,missed a sub 6 because of that!

 

I run a long cage rd.

I also run Truvativ 39t big ring and not the XX version(expensive)

When I replace chain en blade it still happens down the bumpy stuff.

 

Any advice on this what the problem can be?

cheers

[Iron]

sram !! that is your problem .

 

Just kidding , check your limit screws on your FD, it sounds like its shifting too far over .

[Capricorn]

during attakwas, when did your chain drop?

 

after the chainring and chain replacement, dropping off bumpy stuff sounds like u need a chain tensioner, or shorter chain.

[andretraut]

Problem is you should not run your bike, but ride it!

[George Nel]

Problem is you should not run your bike, but ride it!

useless info,thanks moron

[manbearpig]

useless info,thanks moron

Geez why so aggro? Maybe the sand fell out your vagina and got stuck in the chain? More than likely though it is the limit screws that need to be set correctly. It should take 30 secs to fix.

[NINER_boy]

Hi Sam Fisher

 

Had the same problem on my XX bike.

 

Check the limit screws on the FD, and set the tune a 1/2 turn at a time to push the lower lomit further out (towards the crank).

 

What I eventually did, is;

1. Set your rear cassette to the lowest gear (biggest cog, "still confusing" )
   
2. Front smallest chainring
   
3. Set the inner limis screw so that the FD catches on the chain when your rear is in the biggest sprocket.
   
4. Set the limit JUST so that the FD does NOT touch the chain (smallest chainring and biggest sprocket Rear).
   

You should be set.

 

Did that, and mine workis like a CHARM, and also had that trouble for looong

[zaShadow]

My XO is also doing this when the road becomes REALLY bumpy.

 

So far this only happens going down Breedt's neck, but have happened about three or four times. Gearing the fd down to the smaller blade for the worst sections has helped so far, and luckily this downhill is steep enough so that being in the smaller blade doesn't really interfere.

 

I will definitely try NINER_boy's suggestion.

[Niner]

Had simular issues, check your FD, it get it to 1mm above the big ring....they say 1-3mm but at 1mm this stopped.

[Bike Mob]

I may have missed it but is your chain:

 

a) Going over the top of the big ring

b )Falling into the BB area

 

these are different fixes, NINER_ Boy suggested a fix for option b ) I would add that the limit needs to be slightly lower than just off rubbing when in the biggest cog maybe 3mm, then use cable tension to adjust it closer so that it ends in the 1mm from rub position. This I have found uses the cable tension even on release to slow down the "slap" when the chain gets derailed.

 

for Option a) it's a combination of limit, chain tension and Front derailer height. You may need to drop the FD to make sure the chain cannot creep underneath it. Then set the limit to make sure it's locked. Correct chain tension and riding in a bigger cog (not the 11) downhill will keep the RD tought and reduce slap and chain slop so that it doesnt fall off.

Edited January 17, 2012 by Tarmac's Revenge

[zaShadow]

for Option a) it's a combination of limit, chain tension and Front derailer height. You may need to drop the FD to make sure the chain cannot creep underneath it. Then set the limit to make sure it's locked. Correct chain tension and riding in a bigger cog (not the 11) downhill will keep the RD tought and reduce slap and chain slop so that it doesnt fall off.

 

Ah... very cool. Will drop die FD a little and see the effect.

[amasendeinja]

Had the same issue on X9 and none of the above fixes worked. Specifically jumping off the bottom of the big ring on a hardtail. To check just lift your bike by the saddle about a foot off the ground and let it drop - my chain dropped off the big ring 10/10 times doing this.

 

Finally ended up calling Cape Cycles and before I could really launch into my long sob story, the guy said he knew of the problem. SRAM got a bad batch of springs at some point in late 2010 which affected XX, XO and X9 in that the spring tension was insufficient to prevent the chain jumping off the chainring(s) on technical stuff. Replaced my RD under warranty and no problems since.

 

The spring on the new RD is seriously strong.

 

Not saying this is your problem, but if you've exhausted all of the options/fixes mentioned above, then maybe you've got the same problem I had.

[Bat-ass]

Must run medium cage derrailers on 2 x 10.. i had this problem with a long cage. i changed to medium cage and make sure your chain is not too long... no slapping, tension kept tight.... Go medium cage!!

[George Nel]

Had the same issue on X9 and none of the above fixes worked. Specifically jumping off the bottom of the big ring on a hardtail. To check just lift your bike by the saddle about a foot off the ground and let it drop - my chain dropped off the big ring 10/10 times doing this.

 

Finally ended up calling Cape Cycles and before I could really launch into my long sob story, the guy said he knew of the problem. SRAM got a bad batch of springs at some point in late 2010 which affected XX, XO and X9 in that the spring tension was insufficient to prevent the chain jumping off the chainring(s) on technical stuff. Replaced my RD under warranty and no problems since.

 

The spring on the new RD is seriously strong.

 

Not saying this is your problem, but if you've exhausted all of the options/fixes mentioned above, then maybe you've got the same problem I had.

My rd spring is shot yes,does'nt change to the smallest 2 gears on the cluster.thanks,also trying out med cage