HELP installed rear derailleur wrong?
 

I'm brand new to bike maintenance. I had to put in a new inner tube in the rear wheel and to remove the wheel, it requires I remove the rear derailleur first. I should have taken a pic of it before so I knew what it was supposed to look like when I put it back on, but I didn't. I'm sure I've put this back together incorrectly since the chain is slack and it doesn't look like the second picture, which I assume is how it's supposed to look. The derailleur turns into that position but doesn't stay there. How do I get it to do that? Did I put it on wrong? This is a Panasonic Sport 500 if that matters. Thanks!

See the curved metal cage on the sides of the derailer's jockey wheels? The path of the chain should follow that curve.

basically you routed the chain backwards.

That was simple. Thanks, you saved the day!

I also appears that the hanger claw is not properly installed:

http://os2.dhs.org/~john/claw.jpg

The fastening bolt should be in the dropout slot (behind the wheel axle), not outside the dropout.

The fastener JohnDThompson points out is shaped to fit into the curve at the back of the dropout. And the slot of the derailleur hanger should line up with the dropout slot. Your axle will not be all the way back in the dropout; this is normal.

Photochic: two new threads?

Couple of (hopefully constructive) suggestions:

REI stores host bike maintenance classes -- a free one that helps you with roadside emergency type repairs, and a fairly cheap one that helps you learn basic bike maintenance;

Park Tools -- the main mfgr of bike tools -- has Park Tool School in lots of cities.

Park also puts out a GREAT DIY bike repair book, AND has all the same info on their website.

Lastly, the late Sheldon Brown ... left a wonderful legacy of bicycle info. If you can't find it on Sheldon's website, then it probably isn't worth knowing ;)

Welcome to bike repair :thumb:

For future reference, there is no need to remove either the derailleur or the chain to get the rear wheel out. Shift into the smallest cog on the back, loosen the axle nuts, and slide the axle forward in the frame dropout slot. The derailleur can swing back out of the way as the axle drops out of the frame. Leave the chain intact, routed through the derailleur. After you've fixed your wheel, position it under the frame with the chain resting on the smallest cog. Slide the axle back in the dropout slot, center the wheel in the frame and snug down the axle nuts. The derailleur will swing back forward as the chain picks up tension. Check the brakes to make sure they still work before you ride off.