View Single Post
Old 04-30-18, 09:06 PM
  #6  
Andrew R Stewart 
Senior Member
 
Andrew R Stewart's Avatar
 
Join Date: Feb 2012
Location: Rochester, NY
Posts: 11,460

Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Raleigh Pro, Trek Cycle Cross, Mongoose tomac ATB, GT Bravado ATB, JCP Folder

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1677 Post(s)
Likes: 0
Liked 9 Times in 8 Posts
The lower edge of the inner cage plate needs to clear the tops of the middle ring. So a der with too "deep/tall" an inner cage plate shape could rub an a 42T ring but clear a 39t ring. Also the cage's contours might not match where the chain is running past them if the ring was the wrong size, affecting the chain's lift during shifting. Andy
Andrew R Stewart is offline