Derailleur Help
 

Newb here. My rear derailleur cage (I think that's what it's called - the part that houses the two "pulley" cogs) jumps down and back up about every 1/4 rotation of the wheel. This is after the bike falling off a buddy's truck.

Also, the inner front derailleur cage rubs against the side of the chain in some gears, and I am unable to correct by adjusting the low gear screw.

Are these fixable without taking to a bike mechanic? I am fairly mechanically inclined, but I'd like to know what I'm looking to fix before I start tinkering. Thanks for any help in the right direction :)

Don't use gears that 'cross' the chain - eliminates rubbing
DR cage may be bent or broken, chain may have stiff links - not enough info

Enjoy

The front derailleur can be adjusted with the barrel on the shifter. The limit screws will only stop the chain coming off, and have no effect on the middle ring (assuming a triple ring up front). Bear in mind that the chain will rub if you select gear combos such as big-big (which you shouldn't by the way).

Does the rear derailleur jump in all of the cogs or just one or two? It could just need adjusting, hanger could be bent, could be a stiff chain link (unlikely I think), etc. etc. Almost certainly fixable though.

The park tool website has walkthrough for most little repairs, take a look on there.

Too slow again. Must type faster!

The rear jumps at big-big (didn't know this was a no-no, good to know-know ;) ). Doesn't appear to be bent; I looked at it from the back and the two pulley cogs (am I using the right term here?) line up visually.

I will give the shifter barrel a try tonight and check out the site you recommended. Much thanks!

Before you start adjusting things take a look at the derailleur hanger. Since your problems seem to have occurred after a "fall" I suspect that the hanger may be bent. There is a special tool for re-aligning the hanger, but you may be able to improvise.

Al

Will do, thanks!