wunderkind

Hi,

I got this Sora RD3400. I don't know what is it. But the pulley cage seems to be at an on angle. For the life of me, I can't figure out why the springs this forward. Can anyone tell me what is wrong? Do I need to tighten/loosen anything?

AlphaDogg

That's very strange. The fact that the chain is drooping off from the pulley tells me that chain tension is not holding it in place--that and the fact that it's in your smallest cog. Try rotating the cage back. Maybe it's caught on something.

chriskmurray

There is a tab on the derailer body that the pin sticking out of the outer cage catches on that keeps it from doing that. My guess is that tab broke and caused the spring that tensions the cage to either break or come out of its seat.

wunderkind

Wow. I am bummed if that is the case! Can you tell me how to check for this pin?
I can swing the cage back. But it keeps springing forward.

chriskmurray

Do you see the little pin on the derailleur cage just above where it pivots off the derailleur? As you swing it back look for a little knuckle on the derailleur that is probably pretty chewed up. You may be able to build something back up to act as a stop if that is the case and the cage tension feels normal when pulled back into place, but that is rarely the case. How old is the derailleur?

chriskmurray

It looks pretty new, Shimano does offer a 2 year warranty on everything below dura-ace and XTR so you may get lucky and have them replace it for free because the derailleur is likely shot but you may get lucky.

wunderkind

Weird, my post reply disappeared.

Well you are right. I inspected the RD and indeed a piece of something as you described were sheared off. I thought these are made of metal! It is brand new. So I'm gonna start an RMA with the seller. Grr!!! I am so looking forward to ride tomorrow! Thanks chriskmurray.

onespeedbiker

Are we talking about the tab that holds B angle adjustment screw?

From Park Tool;

e_guevara

It's the derailleur cage return spring.



(Images taken from the ParkTool website)

The spring tab might have broken off.

Like what the previous poster said, return it to the shop for a replacement. The Sora RD is non-rebuildable.

chriskmurray

It is usually just soft aluminum and this piece really should not see much load at all unless it got hit in shipping so softer materials is usually not a problem. Since it is new, get the shop that sold you the bike to replace it. Glad I could be of some help.

lostbob88

Your chain is not properly wrapped around the upper jockey wheel. google "rear derailleur" and look at the photos.

AlphaDogg

Ah! I didn't notice that. OP, did you build your bike? If it came stock like that, somebody deserves to lose their job.

Edit: oops.

It is wrapped correctly. This is what my 105 5700 rd looks like (it's near parallel because it's in the big-big combo... I know, crosschaining is bad....)

e_guevara

It is correctly threaded on the RD. The cage is stretched out because of loss of spring tension on the cage.

lostbob88

Guess it is...Purchasing new glasses!

Kimmo

Disassemble the lower pivot and inspect. I'd say 50/50 fixable/replacement.