Drop-out or derailer bent?
 

Hello

Can anyone take a look a these pics and see what they think is bent here? I think it's the derailer cage, but from what I've read it's more common for the dropout to see damage.

http://bikeforums.net/attachment.php...hmentid=335967http://bikeforums.net/attachment.php...hmentid=335968http://bikeforums.net/attachment.php...hmentid=335970

Thanks,
Tom

I can't tell from the photos because of camera angles. But here's some hints for how you can make your own judgement.

Bent hangers almost exclusively bend inward. That would have the entire derailleur hanging with the bottom (of the cage) closer to the wheel than the top. Further confirmation may be if there's visible scratch damage on the outermost part of the derailleur (just to the outside of where it says XT).

OTOH of the cage is twisted rather than bent in at the bottom, than it would argue that it's a cage issue. You can also eyeball that the two pulleys are on a single plane, or lay a straight edge against the inner cage plate.

BTW- as I said the camera angle makes it hard to tell, but it looks OK to me. What functional problem are you having?

I agree that bending the dropout is more common but I can't tell for sure which is bent by looking at your photos.

I can adjust a 7-speed or an 8-speed adequately well by eyeball but I like to use a gauge to align 9-speeds because the cogs are closer together and are consequently pickier about accurate alignment. It's not a too expensive service, I'm guessing $15.00 to $20.00. One other nice thing about aligning the dropout with a gauge is, if your derailleur still leans inward, you'll know that it has to be the derailleur.

If you look closely at the first picture (small ring-small cog), you can see the chain is getting pulled off of the pulley. It's kind of wedged between the cage and the idler wheel. If you look at the chainline between the jockey and idler wheels, you can see there is a pretty decent angle.

In the second picture, it's riding on the idler wheel just fine (small ring-small cog).

You need to have the drive train in a gear that results in the cage being more vertical and then look (or take the photo) from lower down, toward the chainwheel like the photo below.
http://bikeforums.net/attachment.php...hmentid=335972

http://bikeforums.net/attachment.php...hmentid=335973http://bikeforums.net/attachment.php...hmentid=335974

I think it's clearer to see with the bike turned upside down...

It could be that the cage is twisted so the lower pulley is out of plane with the chain coming to it from the bottom of the chainring. Understand that there's normally some of this since the RD moves in and out so the pulley can' line up with every chainring.

The other possibility is that the pulley is worn, and the chain coming from a normal angle is running up over the side.

Do some eyeball gauging sighting down the chain like a rifle, and check the condition of the lower pulley.

In any case I doubt it's the hanger which seems to have the RD hanging straight up and down, and for the chain to derail to the inside of the lower pulley it would mean that the lower pulley is outside of the chainrings, not bent inward.

So twisted cage, or worn lower pulley, or some combination of both are more likely, though it is possible for the hanger to be twisted.

Sorry to spam you with pictures, but here is one last attempt at showing the angle you're recommending:

http://bikeforums.net/attachment.php...hmentid=335977

FBinNY, based on your response, I would say the derailer appears to be twisted. If so, can this generally be repaired?

It also looks to me like the cage is bent so that the pulleys are not in line with each other. That can be remedied, but a shop could charge as much as for a derailleur. If the derailleur itself is twisted replace it. There are too many angles in my view - and in my experience - to be worth attempting to get right again.

Most shops won't bother trying to straighten a bent cage because it's too time consuming. A mechanic at a co-op, or a "dirt under the nails shop" would probably be more willing to give it a shot.

Straightening RD cages is actually pretty easy if you have good eyes and hands. The plates aren't that strong or rigid. I've straightened plenty of cages over the years, but it's usually more by way of an on the road emergency repair.

If the RD is otherwise in good shape, give it a go yourself since you don't have much to lose. Simple tweaks can usually be done with an adjustable wrench fitted over the bottom of the cage. More complicated bends are best done off the bike. I usually hold the bottom o the cage in a vise and work from there.

https://www.lynskeyperformance.com/s...-dag-2_001.jpg

......find some place with one of these.. if your hanger checks out as straight, the derailleur cage is the only other option.

I would be reluctant to advise you to start bending things based on your photos. Work methodically in a process order.