Go Back  Bike Forums > Bike Forums > Road Cycling
Reload this Page >

Rear derailleur cage striking larger sprockets in cassette. What am I doing wrong?

Notices
Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

Rear derailleur cage striking larger sprockets in cassette. What am I doing wrong?

Old 09-23-10, 08:02 AM
  #1  
Senior Member
Thread Starter
 
Join Date: Oct 2007
Posts: 97
Likes: 0
Liked 0 Times in 0 Posts
Rear derailleur cage striking larger sprockets in cassette. What am I doing wrong?

I'm running a rear SRAM cassette with a huge outer-most sprocket (32 teeth). I currently have it set up with a Campy Nuovo Record rear derailleur from the 70s. When attempting to shift into the largest sprocket (easiest gear) the derailleur cage immediately above the jockey pulley comes in contact with the sprocket.

Do I need to buy a derailleur with a longer parallelogram between the derailleur bolt and the jockey pulley? Do manufacturers commonly list the length of this parallelogram?

Have I simply adjusted something incorrectly?
Purp is offline  
Old 09-23-10, 08:13 AM
  #2  
Burning Matches.
 
ElJamoquio's Avatar
 
Join Date: Jan 2006
Location: San Jose, CA
Posts: 9,714
Liked 1,005 Times in 678 Posts
"B-screw?"

Campagnolo®
Some Campagnolo® model derailleurs have a body tension adjustment at the pulley cage, not at the upper pivot. The screw is basically a "rack and pinonquot; system. The cage spring plate rotates to increase or decrease tension. The upper pivot and lower cage pivot springs oppose one another. In this system, the upper spring is fixed. Increasing cage tension (turning screw clockwise) will bring the upper pulley closer to the cog. Decreasing cage tension (turning screw counter-clockwise) will increase the distane between upper pulley and cog.

https://www.parktool.com/repair/readhowto.asp?id=64
__________________
ElJamoquio didn't hate the world, per se; he was just constantly disappointed by humanity.
ElJamoquio is offline  
Old 09-23-10, 08:14 AM
  #3  
pan y agua
 
merlinextraligh's Avatar
 
Join Date: Aug 2005
Location: Jacksonville
Posts: 31,408

Bikes: Willier Zero 7; Merlin Extralight; Calfee Dragonfly tandem, Calfee Adventure tandem; Cervelo P2; Motebecane Ti Fly 29er; Motebecanne Phantom Cross; Schwinn Paramount Track bike

Liked 822 Times in 425 Posts
Yeah you can try playing with the B screw. But the bigger problem is you're beyond what that derialleur was designed for. Without looking up the spec, I doubt Nuovo Record was intended to shift bigger than about a 28.

And all the NR derailleurs I've seen were short cage, so it wouldn't have the chain wrap capacity either, depending on what you're using for front chainrings.

The good news is that if it's in good shape you can Ebay for enough to buy a nice modern derailleur with the right capacity.
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.

Last edited by merlinextraligh; 09-23-10 at 08:18 AM.
merlinextraligh is offline  
Old 09-23-10, 08:16 AM
  #4  
Burning Matches.
 
ElJamoquio's Avatar
 
Join Date: Jan 2006
Location: San Jose, CA
Posts: 9,714
Liked 1,005 Times in 678 Posts
Yup, check chain length... (it might be too short now)... will prob have some chain slack at small/small.
__________________
ElJamoquio didn't hate the world, per se; he was just constantly disappointed by humanity.
ElJamoquio is offline  
Old 09-23-10, 08:21 AM
  #5  
pan y agua
 
merlinextraligh's Avatar
 
Join Date: Aug 2005
Location: Jacksonville
Posts: 31,408

Bikes: Willier Zero 7; Merlin Extralight; Calfee Dragonfly tandem, Calfee Adventure tandem; Cervelo P2; Motebecane Ti Fly 29er; Motebecanne Phantom Cross; Schwinn Paramount Track bike

Liked 822 Times in 425 Posts
Looked it up: Maximum cog 28 (although arguably 25) Capacity 25.



https://www.disraeligears.co.uk/Site/...rd_style).html

Also I don't think it has a B screw like a modern slant parallel derailleur.

The guide in the above link talks about a B screw, but it appears to be referring to the low limit screw.

I sold my bike with NR in 1991, so I don't recall from memory.
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.

Last edited by merlinextraligh; 09-23-10 at 08:32 AM.
merlinextraligh is offline  
Old 09-23-10, 08:21 AM
  #6  
Senior Member
Thread Starter
 
Join Date: Oct 2007
Posts: 97
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by merlinextraligh
But the bigger problem is you're beyond what that derialleur was designed for. Without looking up the spec, I doubt Nuovo Record was intended to shift bigger than about a 28.

And all the NR derailleurs I've seen were short cage, so it wouldn't have the chain wrap capacity either, depending on what you're using for front chainrings.
Yeah, I figured. I built this bike out of the parts box so I was just seeing what I could get away with.


Originally Posted by merlinextraligh
The good news is that if it's in good shape you can Ebay for enough to buy a nice modern derailleur with the right capacity.
What spec do I look for when buying? Are most modern derailleurs able to accept such a large sprocket? Should I get a MTB derailleur?
Purp is offline  
Old 09-23-10, 08:25 AM
  #7  
Senior Member
Thread Starter
 
Join Date: Oct 2007
Posts: 97
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by merlinextraligh
Looked it up: Maximum cog 28 (although arguably 28) Capacity 25.

https://www.disraeligears.co.uk/Site/...rd_style).html
Awesome, thanks. That looks really similar to my model. If you look at that photo you can see there's a very small screw below and to the left of a larger bolt on the derailleur.




Could this be the B screw?

Last edited by Purp; 09-23-10 at 10:18 AM.
Purp is offline  
Old 09-23-10, 08:31 AM
  #8  
pan y agua
 
merlinextraligh's Avatar
 
Join Date: Aug 2005
Location: Jacksonville
Posts: 31,408

Bikes: Willier Zero 7; Merlin Extralight; Calfee Dragonfly tandem, Calfee Adventure tandem; Cervelo P2; Motebecane Ti Fly 29er; Motebecanne Phantom Cross; Schwinn Paramount Track bike

Liked 822 Times in 425 Posts
The"B" screw adjusts how the derailluer hangs front to back (i.e. how close it is to the cogs) as oppossed to the limit screws which limit the range of movement inside to out.

If you turn it in,a nd the derailleur pulleys move away from the cogs, then its the "B" screw.

However, I think you're looking at the high limit screw:

https://www.disraeligears.co.uk/Site/...-_page_29.html

But you're so far beyyond what that derailleur was intended for, its never going to shift acceptably.
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
merlinextraligh is offline  
Old 09-23-10, 08:33 AM
  #9  
Senior Member
Thread Starter
 
Join Date: Oct 2007
Posts: 97
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by merlinextraligh
If you turn it in,a nd the derailleur pulleys move away from the cogs, then its the "B" screw.
Yeah, the screw in question is certainly not an l/h adjustment screw.

Originally Posted by merlinextraligh
But you're so far beyyond what that derailleur was intended for, its never going to shift acceptably.
Well, anyone in the market for a gently used Nuovo Record derailleur?
Purp is offline  
Old 09-23-10, 09:55 AM
  #10  
Over the hill
 
urbanknight's Avatar
 
Join Date: Mar 2006
Location: Los Angeles, CA
Posts: 24,425

Bikes: Giant Defy, Giant Revolt

Liked 1,264 Times in 718 Posts
Originally Posted by Purp
What spec do I look for when buying? Are most modern derailleurs able to accept such a large sprocket? Should I get a MTB derailleur?
You want one with a max cog of 32 (or at least close to it) and you need to calculate the total chainwrap of your gearing and compare that with the derailleur specs. I'm quite confident a mtb derailleur or SRAM Apex will work. Other ones are a maybe.
__________________
It's like riding a bicycle
urbanknight is offline  
Old 09-23-10, 10:03 AM
  #11  
Senior Member
 
Brian Ratliff's Avatar
 
Join Date: May 2002
Location: Near Portland, OR
Posts: 10,123

Bikes: Three road bikes. Two track bikes.

Liked 4 Times in 4 Posts
There was no such thing as a 32 tooth cog in the 70s. You are probably well past the capacity of the derailleur. A modern long cage mountainbike derailleur is your best bet to make things work.
__________________
Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --the tiniest sprinter
Brian Ratliff is offline  
Old 09-23-10, 10:15 AM
  #12  
Senior Member
Thread Starter
 
Join Date: Oct 2007
Posts: 97
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Brian Ratliff
There was no such thing as a 32 tooth cog in the 70s.
Right, these were my suspicions. Thanks for all the help everyone, even if for a silly problem. Still, perhaps someone else will make the same mistake.

I ordered a 9-speed SRAM Apex with a 34t largest cog/max capacity.
Purp is offline  
Old 09-23-10, 04:36 PM
  #13  
Burning Matches.
 
ElJamoquio's Avatar
 
Join Date: Jan 2006
Location: San Jose, CA
Posts: 9,714
Liked 1,005 Times in 678 Posts
Order a new chain too.
__________________
ElJamoquio didn't hate the world, per se; he was just constantly disappointed by humanity.
ElJamoquio is offline  
Old 09-23-10, 05:19 PM
  #14  
"Chooch"
 
ciocc_cat's Avatar
 
Join Date: Jun 2010
Location: Prairieville, Louisiana
Posts: 1,659

Bikes: Late 1990s Ciocc Titan

Likes: 0
Liked 2 Times in 2 Posts
Originally Posted by Brian Ratliff
There was no such thing as a 32 tooth cog in the 70s. You are probably well past the capacity of the derailleur. A modern long cage mountainbike derailleur is your best bet to make things work.
Having ridden a lot in the 1970s, I beg to differ. Suntour had a 14-32 tooth freewheel (which I used on my early 1970s Gitane TdF club rider - photo attached), but you needed a touring derailleur with a long cage to handle the chain wrap.
Attached Images
File Type: jpg
gitane0001..jpg (103.0 KB, 7 views)
ciocc_cat is offline  
Old 09-23-10, 05:50 PM
  #15  
Senior Member
 
DannoXYZ's Avatar
 
Join Date: Jul 2005
Location: Saratoga, CA
Posts: 11,736
Liked 10 Times in 6 Posts
Originally Posted by Brian Ratliff
There was no such thing as a 32 tooth cog in the 70s. You are probably well past the capacity of the derailleur. A modern long cage mountainbike derailleur is your best bet to make things work.
I have a Suntour cog-board for Perfect/Winner/New Winner/Winner Pro 5-7spd freewheels. There was most definitely a 32t freewheel cog available back then. Many touring bikes had 14-17-23-28-32t 5-speed freewheels and half-step chainrings.

Another factor that affects max-tooth capacity is the hanger-drop amount. Not all derailleur hangers on all bikes are the same. Touring bikes tend to have hangers that place the derailleur lower than racing bikes. Just a little extra length at the end makes a huge difference in performance.
DannoXYZ is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
enderconka
General Cycling Discussion
13
02-11-18 12:02 PM
lantti
Classic & Vintage
12
09-24-17 03:37 PM
TimothyH
Road Cycling
4
07-12-16 04:00 PM
TP_Mantis
Road Cycling
7
05-13-15 10:56 AM
wunderkind
Bicycle Mechanics
14
09-16-12 11:27 PM

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Your Privacy Choices -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.