Bicycle Mechanics - Sudden "floppy" rear derailleur

I have a 1990 Trek 720 multi track hybrid bike that i use for a beater, well at least that is my intent. So far I have hardly been able to keep it running long enough to use to ride to work. I bought the bike fairly cheap on ebay so i have been trying to get by without spending much on it.

It arrived with a broken rear derailleur. A BF member here was kind enough to give me a new rear suntour derailleur and it worked alright for about 30 miles and then today on the way to work, i started to hear a rattling in the rear drive train. Upon inspection, the derailleur is tight to the frame but there is a great deal of flop in the jockey wheel/cage mechanism. IOW, it is very loose and is bouncing and rattling when i hit bumps.

I see no way to tighten it and can't understand why it just all of the sudden started to do this. Any ideas?

http://xs313.xs.to/xs313/07135/58294E0CDC1C11DBA18E00112475A276.jpg

Not My derailleur

Just a guess but you may have sheared that rivet/pin below your arrow that hold the cage on. Can you wiggle it by hand? If you're handy you could drill and repin it. I would PM your donor to see if he ran into any problems.

I can not tell from the photo but....Are there still 2 jockey wheels on this derailleur?????

I can not tell from the photo but....Are there still 2 jockey wheels on this derailleur?????

This is not the actual derailleur. It is a photo grabbed off of the internet. My derailleur is still on my bike, because i need it to ride home from work. :D

YOU CAN SEE IT HERE> (http://media.putfile.com/Suntour)

That pin does seem a little loose. maybe replacement is not too hard. but it doesn't appear to be completely sheared, although you might find out that it is if you yanked harder. that's one thing I haven't played with, so I'm not much of a guide, but it is something I would fell comfortable tackling.

I think I sent you that derailer. I didn't notice anything wrong with it, but it was a take off and I never tried to use it. It's strange that it seems to be worn out, yet the pulleys don't show excessive wear. I suppose they could be replacements. Also, the Trek I took it off of doesn't appear to have a lot of miles on it.

Yeah, I thought it looked pretty good to out of the box. In fact it worked fine for a short while. I might have ridden 50 miles total on the bike, just a few trips back and forth to work. Then today it started to ghost shift and then on the last return trip to work, it started to really rattle when i hit bumps.

It's wierd that it would go from functioning fine to rattling in such a short amount of miles. I am not all that familiar with this old suntour stuff, but my shifters are called Accu-shift. They are sort of a cross between indexing and friction. The front der. is friction and rear is poor performing indexing.

Thanks for sending me the derailleur. I wish it would have worked out. Now I just need to figure out what to do with the darned thing.

I say do what I did and replace the Suntour stuff with Shimano.

I say do what I did and replace the Suntour stuff with Shimano.

I would like to but I don't know if i want to invest that much in it. If I am thinking correctly I will need:

New crankset, new chain, new shifters/brake levers (combo on now), new rear derailleur, new cassette,maybe new front derailleur and new rear wheel. Is this right? That will amount to more than i want to spend on the bike i think. :mad:

Just buy a used indexable Shimano 105/600 rear derailleur and go friction. ($10-15) then you can add index shifters if you want later. The rest of your drivetrain will be fine.

Just buy a used indexable Shimano 105/600 rear derailleur and go friction. ($10-15) then you can add index shifters if you want later. The rest of your drivetrain will be fine.

The current rear shifter is index, so I don't think that will work.

Most indexable DT and bar end shifters can be converted to friction - either by a switch (turning a screw) or by removing an internal washer.

Most indexable DT and bar end shifters can be converted to friction - either by a switch (turning a screw) or by removing an internal washer.

These are trigger shifters, called accushift. (which they aren't by the way)

If your guide wheels are okay.I'd look at the main pivot,where it attaches,(the 5-MM bolt).The C clip that makes it pivot and holds it all together,might have got lost,loose.Assuming the cable and dropout ear and h and l setting are fine.