Because of Q rings I've always used rotor chain catcher. However, I was still dropping chain once every few rides. Although this was annoyance, dropped chain has never scratched the frame and I've always thought the chain catcher stopped the chain from harming my bike. That is until last Sunday. I was cruising along at 20kph with very light torque on the pedal and the chain was dropped again, but this time the chain was jammed between the chain ring and the frame and scratched my beautiful S5 :( Once home, I started to inspect the chain catcher, trying to figure out why this device that was supposed to prevent chain from dropping wasn't functioning properly. The gap between the catcher and the ring was only 1mm, but upon closer inspection I've realized that the catcher wasn't parallel to the ring but rather come in at an angle. So the gap was more like V. Long story short, I've ditch the Rotor chain catcher and put on a k-Edge, adjusted it to be parallel to the chainring. I've went through some very wonky shifting to drop the chain on purpose and voila! K-Edge actually "catches" the chain and the chain is back on the ring. All this time I thought the chain catcher was just there to minimize the damage to the frame once the chain is dropped. I believe K-Edge works because 1) it has wider profile over Rotor and 2) you can fine tune the angle because it has wide bolt hole. Only two negatives with K-edge are that it's heavier and a tad bit more costly compare to Rotor.

I'm just curious as to why your bike is dropping the chain so often.  If the lower limit screw on your front derailleur is properly adjusted, a chain drop should be a very rare event. I haven't dropped a chain in two years.

My situation has nothing to do with low limit because the chain gets sucked when shiftin up to larger ring.

Q ring doesn't like to be shifted when its in the smaller radius, and ocassionally the chain gets sucked in.

 I've had problems with my Rotor compact crank throwing the chain.  I have a k-Edge chain catcher and I'm telling you the chain can still get jammed under it and then you are in a world of poo.  My BB is all scratched up already.  I think there is another thread on this.  The Rotor crank will wedge the chain in and jam it against your BB scratching the hell out of it.

I have the scars to prove this.  Could have been better engineered.

I believe what you're describing is chainsuck, if your problem occurs when the chain fails to fully dislodge from the small chainring when shifting to the large chainring. As you pedal, the chain gets sucked up and right into the frame from the bottom. It jams in there pretty tightly and screws up the paint. A chain catcher doesn't help though, it only help when moving from large to small chainring.

SSB:

I believe what you're describing is chainsuck, if your problem occurs when the chain fails to fully dislodge from the small chainring when shifting to the large chainring. As you pedal, the chain gets sucked up and right into the frame from the bottom. It jams in there pretty tightly and screws up the paint. A chain catcher doesn't help though, it only help when moving from large to small chainring.

 

 

I have had both issues.  Jammed under the chain catcher AND sucked up into the frame bottom.

FML.

I has such a love and hate relationship with Q rings.

How the hell are the pros using Q rings if the shifting is this wonky?

and I have had my Rotor Q rings for 3 years one drop.

 I was having the same problem with my Q-rings with regards to the chainsuck.  It stopped when swapped out the SRAM bottom bracket for the one from Rotor.  I don't know if the bracket had anything to do with it as so many things are readjusted afterward but the it is quite different from the SRAM one.

I haven't had any problems with my compact Q-Rings. I had more chain suck with the Rival crankset that came with the bike.