Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 04-05-08, 11:32 AM   #1
Hammertoe
A Little Bent
Thread Starter
 
Hammertoe's Avatar
 
Join Date: Mar 2006
Location: Struggling up a hillside in Vermont, USA... ..........................................
Bikes:
Posts: 2,858
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Rear Derailer Pulley Wheel Rumble....

I am finishing my Scott CR1 build and almost have it dialed in...

The pulley wheel (lower jockey wheel) rumbles when in the lowest gear (34/29)...

Any suggestions to fine tune it...

The rear derailer is a Record long cage...

Thanks...
__________________
Hammertoe is offline   Reply With Quote
Old 04-05-08, 12:52 PM   #2
joejack951
Senior Member
 
joejack951's Avatar
 
Join Date: May 2004
Location: Wilmington, DE
Bikes: 1984 Trek 660, 2003 Specialized Hardrock, 2004 LOOK KG386i, 2005 Iron Horse Warrior Expert, 2009 Pedal Force CX1, 2014 Islabikes CNOC 14 (son's)
Posts: 9,963
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 68 Post(s)
Adjust the B-screw maybe? With that large of a cog on your cassette, there's a good chance that the jockey wheel is rubbing on it if you left the default B-screw adjustment in place. Chances are, you'll need to screw it all the way in to remove the rubbing. I had to do the same to get a Shimano road derailler to clear a 28 tooth cog.
joejack951 is offline   Reply With Quote
Old 04-05-08, 01:21 PM   #3
JiveTurkey
Low car diet
 
JiveTurkey's Avatar
 
Join Date: Aug 2007
Location: Corvallis, OR, USA
Bikes: 2006 Windsor Dover w/105, 2007 GT Avalanche w/XT, 1995 Trek 820 setup for touring, 201? Yeah single-speed folder, 199? Huffy tandem.
Posts: 2,407
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
2001 and later Campagnolo uses an A-tension screw, which works opposite of the B-tension screw found on Shimano. http://sheldonbrown.com/derailer-adj....html#btension

I don't know much about Campagnolo drivetrains, but are you sure you're not exceeding the max cog and/or the max capacity (or whatever Campagnolo calls it) by too much? Is the upper pulley bumping into the cog, causing the lower to rattle front-to-back? Adjusting the A/B tension will help but only to so much of an extent if the specs are being exceeded.
JiveTurkey is offline   Reply With Quote
Old 04-05-08, 03:06 PM   #4
BCRider
Senior Member
 
BCRider's Avatar
 
Join Date: Mar 2008
Location: The 'Wack, BC, Canada
Bikes: Norco (2), Miyata, Canondale, Soma, Redline
Posts: 5,456
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
The lower jockey wheel? One of the jockey wheels is fairly well located and the other floats a little. I can't remember at the moment which is the more loose of the two. The other thought is that the bushing or pin is worn out so that it CAN wobble and create a rumbling sound. Even though it is meant to float side to side a little it's not supposed to wiggle in angle more than a few degrees.

Finally if it's the metal bushing then grease it. I know they say you don't but they can get pretty darn sticky and hold a lot of muck if you don't. The white ceramic bushings I don't grease.
BCRider is offline   Reply With Quote
Old 04-05-08, 03:20 PM   #5
JiveTurkey
Low car diet
 
JiveTurkey's Avatar
 
Join Date: Aug 2007
Location: Corvallis, OR, USA
Bikes: 2006 Windsor Dover w/105, 2007 GT Avalanche w/XT, 1995 Trek 820 setup for touring, 201? Yeah single-speed folder, 199? Huffy tandem.
Posts: 2,407
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
The upper pulley floats to line up better with the cogs.
JiveTurkey is offline   Reply With Quote
Old 04-06-08, 07:41 AM   #6
Hammertoe
A Little Bent
Thread Starter
 
Hammertoe's Avatar
 
Join Date: Mar 2006
Location: Struggling up a hillside in Vermont, USA... ..........................................
Bikes:
Posts: 2,858
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Gotta love BF...

Even with all the characters in the other forums, I can always count on Mechanics...


Although not solved, playing with the "A-screw" and the limit stop, it is better...



It looks like the chain and lower pulley do not line up...

As the chain comes onto the pulley the chain is just slightly to far to the outside (or pulley to close to the wheel) so is 'jumps' every few links causing the rumble...
__________________
Hammertoe is offline   Reply With Quote
Old 04-06-08, 07:45 AM   #7
HillRider 
Senior Member
 
Join Date: Aug 2005
Location: Pittsburgh, PA
Bikes: '''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
Posts: 28,776
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 36 Post(s)
Quote:
Originally Posted by Hammertoe View Post
Gotta love BF...

It looks like the chain and lower pulley do not line up...

As the chain comes onto the pulley the chain is just slightly to far to the outside (or pulley to close to the wheel) so is 'jumps' every few links causing the rumble...
Check your derailleur hanger alignment. If the hanger is bent a bit to the inside it could cause the mis-alignment you are seeing.

Also, it's possible the derailleur cage itself is bent.
HillRider is offline   Reply With Quote
Old 04-06-08, 09:19 AM   #8
dbg 
Si Senior
 
dbg's Avatar
 
Join Date: Nov 2004
Location: Naperville, Illinois
Bikes: Too Numerous (not)
Posts: 2,595
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by HillRider View Post
Check your derailleur hanger alignment. If the hanger is bent a bit to the inside it could cause the mis-alignment you are seeing.

Also, it's possible the derailleur cage itself is bent.
+1
I have one of those derailer hanger alignment bars but don't use it much. I think you can eyeball it pretty well.
__________________
David Green, Naperville, IL USA "The older I get, the better I used to be" --Lee Trevino
dbg is offline   Reply With Quote
Old 04-06-08, 11:25 AM   #9
BCRider
Senior Member
 
BCRider's Avatar
 
Join Date: Mar 2008
Location: The 'Wack, BC, Canada
Bikes: Norco (2), Miyata, Canondale, Soma, Redline
Posts: 5,456
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Once past the first pulley the chain should be routed by the cage. I'm betting the cage itself or the pulley bolts are tweaked. Unless the hanger is WAY off and the chain line is pulling the chain off the pulley.
BCRider is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 04:01 AM.