On Thu, 06 Mar 2008 11:10:36 -0600, A Muzi
wrote:

HarryB wrote:
I purchased an older used bike that is equipped with Paul Thumbies
shifters, a Shimano RD-M739 rear derailleur and a nine speed cassette.
I can't get the indexing to work properly (have tried clamping the
cable on either side of the screw) and wondering if that is because it
seems that the derailleur is an 8 spd one. It does shift ok across the
complete range of the cassette in friction mode.

If I need to purchase a new derailleur (because I want the indexed
shifting), would one like Shimano's RDM510A (that can be purchased
from Nashbar for $18) be a good choice? I need a long cage derailleur.

Your rear derailleur is compatible - 8, 9, 10 no problem. Even six or
seven systems with a longer limit screw.

Likely culprits are gear wire, casing, damaged plastic ferrules or bent
brass ferrules, rust, rear changer not vertical, inner cage plate
installed upside down, worn chain/cassette, worn/damaged pulleys, etc. A
quick perusal by a competent mechanic may be a useful path.

I don't need a competent mechanic when I can turn to you guys!

None of you had the correct answer, but your suggestions steered me in
the right direction. Since I had thought that the derailleur probably
wasn't compatible, I didn't bother to go through the basics first.

This problem is on a recumbent and what I found was that the housing
going to the Rollamajig was pinched between the frame and the seat
support. Not pinched enough to crush the housing, but enough that the
derailleur couldn't float. I didn't have much time to work on it, but
a little tinkering has it shifting quite well.

I am a little concerned about the gap between the largest sprocket and
the jockey wheel. Even with the b-tension adjusting screw backed all
the way out, the distance is still too great. I'm wondering if the
housing going to the Rollamajig isn't the correct length. I didn't
have time to really work on it tonight, so I'll tinker with it and if
I can't get it, I'll post again.

Thanks, guys, for all of your help.
Harry