New chain and new cassette, but chain still skipping

[Patrick C.]

Finally had to replace the chain on my-057, and I got a new cassette as well.  I thought about going to 1X, but didn't want to replace everything else so I went with a straight replacement of what I had before, XT cassette and chain (HG whatever it is) to try to keep it simple.  Well not so simple- the chain skips.  Just about everything I've read says that worn chainrings are not as likely to cause skipping, but I can't see what else the problem might be.  Anybody else have this problem when replacing drivetrain parts?

I guess I should have just gone to 1X11.

[Carbon_Dude]

Seems like the chainring and possibly the pulleys on the rear derailleur are bout the only things left that might be worn. 

Have you aligned your rear derailleur hanger, replaced your shifter cable, and adjusted your derailleur once you put on the new cassette?  I think I'd start there. 

Front chainring problems are usually limited to a grinding sound between the chain and chain ring, it shouldn't cause bad shifting in the rear.

[Patrick C.]

Shifting is perfect- under high load the chain jumps off the teeth due to a mis-match.  Can't tell if it is happening on the chainring or on the cassette, but it is only happening on the big front ring (though I probably never had enough torque on the small chain ring to make it skip/jump off the teeth).

[carbonazza]

You can visually check how the chain wraps around the teeth of the ring.
If there is a play or not.

And look at the shape of the ring teeth, if they are still symmetric.
If they look like a wave going forward, the ring is toast.

[Patrick C.]

With the profile of the teeth, it is tough to tell if they are worn or not.  I don't know if there is a single "normal" tooth on the whole thing.   

Anyway, got a new chainring this week and all is well.  The local shop had a take-off SLX chainring from a bike he converted to 1X.  It looks to be pretty much the same as an XT ring, except for cosmetics (it is all black) and it has a longer chain drop pin.  Weight on each one is around 75 g.  I thought the pin would be difficult to shorten, but it is either Al or mild steel- the grinder went through it like butter. 

[Patrick C.]

Forgot to add, make sure you have a T30 torx bit before you try to remove any of the chainring bolts.  I have plenty of T25 bits laying around but they will strip out the T30 heads.