Bicycle Mechanics - Rear Derailleur hanger temporarily pushed into Spokes. How can this happen.

I was riding on a busy street today. Crossed a busy street to enter a left turn lane. as making a left, rear cluster seemed to be bound up. Traffic was busy. Rode from flat to a slight hill. Think I shifted to a larger cog , as I was in the middle chainring.....
Immediately stopped. The Derailleur was pushed into a spoke. I feared the hanger was bent.Guess was not. Tugged on hanger to pull it out, thinking it bent. . Seemed straight, but still hitting a spoke. Walked the bike. Worked on shifting the derailleur and getting it positioned for normal shifting.
Shifted down to biggest cogs and smallest chainring. Hanger later assumed a normal positon for any given chainring position. Initially shifting was difficult.
Rode the bike to my LBS. As shifted more, shifting seemed to improve. Local wrench said derailleur hanger seemed to be not be bent. Shifted fine for him.
My question. Could some bad shifting do this. I am absolutely positive the hanger had positioned the derailleur into the spokes. Something I did.. ? How can a derailleur assume such an inward angle..
Mechanic saw nothing. We will put on new cables before my pending Oregon trip, coming up later this month..

The situation that you describe is fairly common among mountain bikers. If you catch a twig on the bottom run of your chain when it hits your derailleur arm it'll bind up and bend the derailleur into your spokes.

But Retro, it was temporary. It appeared to spring back into its normal position just by running the chain through its cycles...My guess would have been that whatever caused it was caused by my shifting?

When I was racing Downhill, many riders would "dial out" the largest cog (and sometimes the smallest, turning a 9-speed cluster into an 8 or 7-speed) by cranking in the limiting screw to avoid the very thing that happened to you. If you look at how close the rear derailleur is to the spokes, you may see just how easily a good bounce, some flex in the spokes, etc could cause the cage to get caught, especially with long cage SGS derailleurs. This can also happen to a derailleur with worn out pivots. If everything checks out OK, take a closer look at your limiter spacing. The derailleur should be set to go no further than the jockey pulleys lining up with the inside face of the largest cog.

I don't get it. Nothing short of outside, excessive force should deflect either the hanger or the derailleur enough to jam the spokes. I would think it would stay bent in that case.

I don't know, maybe the hanger is so weak it flexes enough to allow the derailleur to make contact in the first place and then bends back under the load of the chain?

It might help to know what sort of specific machinery we're talking about too.

Cheers

Eros..Rode 10 miles after this incident. has me sort of worried. I am about to do some riding up in Oregon..Is the derailleur weakened? now appears normal

My question. Could some bad shifting do this. I am absolutely positive the hanger had positioned the derailleur into the spokes. Something I did.. ? How can a derailleur assume such an inward angle..
Mechanic saw nothing. We will put on new cables before my pending Oregon trip, coming up later this month..Bad shifting has nothing to do with it. Hangers don't randomly reposition themselves. Putting on new cables will do nothing to fix the problem.

Sydney. Hanger seems straight and strong as ever. Wheel trued. Did re-adjust the wheel by loosening the quick release. but, was not that much out of its correct position in the drop outs..I did not think..
but, I sure as **** saw the hanger hitting a spoke.

Sydney. Hanger seems straight and strong as ever. Wheel trued. Did re-adjust the wheel by loosening the quick release. but, was not that much out of its correct position in the drop outs..I did not think..
but, I sure as **** saw the hanger hitting a spoke.The hanger can't hit the spokes. The derailer cage I can buy.

Sydney..Luckily, I stopped riding as soon as I noticed the noise, resistance...Maybe did go 5 feet..Maybe, Better check every spoke.

Unless it broke completely off the frame, the hanger cannot touch the spokes. Measure the distance from your dropouts/deraileur hanger to your spokes. Now measure the length of your deraileur hanger. How can something half an inch long, made of metal, that is a part of your bike frame, bend down and around your cassette and touch your spokes? What you saw was your deraileur hitting your spokes.

The hanger can't hit the spokes. The derailer cage I can buy.
Ditto.

Terminology check....
http://img.photobucket.com/albums/v693/ozstubacca/Cycling/rd_hanger_cage.jpg

The hanger is where the derailleur attaches to the frame.
The cage hold the pulleys and guides the chain.