Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

Shimano chainrings question

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.

Shimano chainrings question

Old 03-05-05, 07:20 PM
  #1  
Old and Slow
Member
Thread Starter
 
Join Date: Jan 2005
Posts: 27
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Shimano chainrings question

I recently purchased a Lemond Maillot Jaune on Ebay. (Dura Ace 9 speed) Overall, the bike is in excellent condition, but on close inspection the 53 t chainring appeared to be worn. The teeth are asymmetrical. I am not talking about the teeth with the tops cut off. I know why they are there. What I mean is the space between the teeth is not a U shape but more like a U shape. However, I have recently taken a close look at some new 9 speed (Ultegra and Dura Ace) chainrings and they are exactly the same. All of the teeth on the big ring have a different slope on the leading edge than they do on the trailing edge. The difference is slight. You have to look closely to see it, but it is definitely there. The 39 t ring is not like this.

Does anyone know the purpose of this? I have a much older Dura Ace bike (circa 1986) and it does not have this abnormality.
Old and Slow is offline  
Old 03-05-05, 07:43 PM
  #2  
mtbikerinpa
Shimano Certified
 
mtbikerinpa's Avatar
 
Join Date: Dec 2004
Location: PA
Posts: 1,839

Bikes: 92 Giant Sedona ATX Custom

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 37 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
If you have referred to a new sample and found it to be the same then there was a design purpose. Usually if there is a bias in the tooth profile it is to keep the rollers seated on the tooth more securely. That is my best guess, it may be the case here or it may not.
mtbikerinpa is offline  
Old 03-06-05, 09:58 AM
  #3  
miamijim
Senior Member
 
miamijim's Avatar
 
Join Date: Aug 2003
Location: Tampa, Florida
Posts: 13,917
Mentioned: 37 Post(s)
Tagged: 0 Thread(s)
Quoted: 321 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Thats normal. Its to allow smoother shifting.
miamijim is offline  
Old 03-06-05, 11:09 AM
  #4  
operator
cab horn
 
Join Date: Jun 2004
Location: Toronto
Posts: 28,321

Bikes: 1987 Bianchi Campione

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 13 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
It's called Hyperglide, it's to facilitate smoother shifting.
operator is offline  
Old 03-06-05, 11:31 AM
  #5  
sydney
Senior Member
 
sydney's Avatar
 
Join Date: Jan 2004
Posts: 9,428
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by operator
It's called Hyperglide, it's to facilitate smoother shifting.
Well, actually it isn't. Hyperglide had been around looooooooooong before that tooth profile showed up.
sydney is offline  
Old 03-06-05, 12:10 PM
  #6  
operator
cab horn
 
Join Date: Jun 2004
Location: Toronto
Posts: 28,321

Bikes: 1987 Bianchi Campione

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 13 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by sydney
Well, actually it isn't. Hyperglide had been around looooooooooong before that tooth profile showed up.
It isn't? What is it?
operator is offline  
Old 03-06-05, 03:43 PM
  #7  
sydney
Senior Member
 
sydney's Avatar
 
Join Date: Jan 2004
Posts: 9,428
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by operator
It isn't? What is it?
How about evolution of Shimano Total Integration?
sydney is offline  

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


Thread Tools
Search this Thread

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

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.