Advertise on Bikeforums.net



User Tag List

Results 1 to 2 of 2

Thread: Rear Derailleur

  1. #1
    Newbie
    Join Date
    Oct 2005
    Posts
    4
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Rear Derailleur

    I am building a second bike with a triple crank set. It is all ultegra. My question is for my rear deraliier do I have to have a long arm or can i use a standard one.

  2. #2
    You need a new bike supcom's Avatar
    Join Date
    Aug 2002
    Posts
    5,434
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    You need to determine the required amount of chain wrap. This is the number of teeth difference between the big/big and small/small chainring/cog combinations. For example, if you have a 52-42-30 up front, and an 11-25 rear cassette, then your required wrap is (52+25)-(30+11)=36. Your rear derailler must be able to take up 36 teeth. The derailleur should also be rated for the 25 tooth cog.

    Now, you can cheat on this if you use discipline and avoid shifting into the big/big and/or small/small combinations. But it's probably best to get the derailleur that is failsafe.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •