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Index Shifting Problems



 
 
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  #1  
Old March 6th 08, 02:16 PM posted to rec.bicycles.tech
HarryB
external usenet poster
 
Posts: 30
Default Index Shifting Problems

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.

TIA,
Harry
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  #2  
Old March 6th 08, 02:40 PM posted to rec.bicycles.tech
Ozark Bicycle
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Posts: 3,591
Default Index Shifting Problems

On Mar 6, 8:16*am, 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.

TIA,
Harry


Are you sure that the RH (rear) shift lever is a Shimano 9 speed
lever?

  #3  
Old March 6th 08, 02:52 PM posted to rec.bicycles.tech
HarryB
external usenet poster
 
Posts: 30
Default Index Shifting Problems

On Thu, 6 Mar 2008 06:40:02 -0800 (PST), Ozark Bicycle
wrote:

On Mar 6, 8:16*am, 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.

TIA,
Harry


Are you sure that the RH (rear) shift lever is a Shimano 9 speed
lever?


On the top of the lever it says, "9s Shimano" and has arrows for SIS
and FRIC. On the side is a sticker that says, "Compatible with RD-7700
(9s) & RD-7400 (8s)"

I assume that means it's 9spd index capable.

Thank you,
Harry
  #4  
Old March 6th 08, 03:01 PM posted to rec.bicycles.tech
Ozark Bicycle
external usenet poster
 
Posts: 3,591
Default Index Shifting Problems

On Mar 6, 8:52*am, HarryB wrote:
On Thu, 6 Mar 2008 06:40:02 -0800 (PST), Ozark Bicycle



wrote:
On Mar 6, 8:16*am, 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.


TIA,
Harry


Are you sure that the RH (rear) shift lever is a Shimano 9 speed
lever?


On the top of the lever it says, "9s Shimano" and has arrows for SIS
and FRIC. On the side is a sticker that says, "Compatible with RD-7700
(9s) & RD-7400 (8s)"

I assume that means it's 9spd index capable.


Yep.

Try:

http://parktool.com/repair/

click on 'rear derailleur adjustment' and follow the steps.

  #5  
Old March 6th 08, 04:05 PM posted to rec.bicycles.tech
daveornee[_151_]
external usenet poster
 
Posts: 1
Default Index Shifting Problems


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.

TIA,
Harry

Could be that there is too much friction in the cable/housing and/or
too much slop in the RD pivots. I would first try new high quality
cable/housing/metal ends, making sure that everying moves extremely
smooth and easy.
With the cable removed see how the RD moves and how the pivots feel.
Also a check of the chain and cassette for a good 9 speed match and
wear conditions is called for. As chains wear they not only elongate,
they also get less laterally stiff.


--
daveornee

  #6  
Old March 6th 08, 04:20 PM posted to rec.bicycles.tech
Werehatrack
external usenet poster
 
Posts: 1,416
Default Index Shifting Problems

On Thu, 06 Mar 2008 08:52:58 -0600, HarryB may have
said:

On Thu, 6 Mar 2008 06:40:02 -0800 (PST), Ozark Bicycle
wrote:

On Mar 6, 8:16*am, 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.

TIA,
Harry


Are you sure that the RH (rear) shift lever is a Shimano 9 speed
lever?


On the top of the lever it says, "9s Shimano" and has arrows for SIS
and FRIC. On the side is a sticker that says, "Compatible with RD-7700
(9s) & RD-7400 (8s)"

I assume that means it's 9spd index capable.


I haven't encountered significant issues with swapping 7/8/9/10s rders
as long as they were, in fact, SIS-compatible. OTOH, the lever is
from Shimano's Dura-Ace line, which has been idiosyncratic at times.
OTOOH, I seem to recall that this particular lever didn't have DA-only
issues. I'd start by checking everything else first.

Check for problems in the cable, and make sure the rear housing loop
isn't brake housing instead of der. It can make a difference. Also,
make sure the cable isn't binding where it crosses the plastic plate
under the BB. And check the adjustment of the B tension screw; that
sometimes makes a difference in shifting accuracy as well.

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.
  #7  
Old March 6th 08, 05:10 PM posted to rec.bicycles.tech
A Muzi
external usenet poster
 
Posts: 4,551
Default Index Shifting Problems

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.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971
  #8  
Old March 7th 08, 04:30 AM posted to rec.bicycles.tech
HarryB
external usenet poster
 
Posts: 30
Default Index Shifting Problems

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
  #9  
Old March 7th 08, 04:26 PM posted to rec.bicycles.tech
Ozark Bicycle
external usenet poster
 
Posts: 3,591
Default Index Shifting Problems

On Mar 6, 10:30*pm, HarryB wrote:
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.



That was why I suggested the "Park Tool RD adjustment" as the first
step. Process of elimination begins with the basics. Occam's Razor.



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


Are you still planning on that long journey?

 




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