Advertise on Bikeforums.net



User Tag List

Results 1 to 3 of 3
  1. #1
    My name is Mike, not Cal
    Join Date
    Jul 2006
    Posts
    474
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Changing the SIS unit in downtube shifters

    Just curious, given a Shimano Dura-Ace 8-, 9-, or 10-speed downtube shifter, could you make it shift one of the other number of speeds by changing just the SIS unit?

    This Shimano tech doc for 7700 9-speed or 8-speed* downtube shifters looks a lot like this one for 7800 10-speed levers. I'm no mechanic, but it looks like the SIS units are interchangeable, and you can buy them here for $30 - $50.

    *I thought 7700 was only 9-speed, so I'm a little confused about the tech doc saying 8-speed.

    I don't plan on doing this, it just crossed my mind that it might be possible.
    "I got my lips chewed off by a dingo!" --David Letterman

  2. #2
    My own worst nightmare
    Join Date
    Jan 2004
    Location
    Madison, WI USA
    Posts
    1,237
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    "8/9" usu. means it'll work on either one (click-stop spacing is the same, or close enough for "government work..."), but cable tension and high/low limit are presumed to be set correnctly on an 8-er that one click-stop just won't be used.

  3. #3
    Senior Member
    Join Date
    Aug 2005
    Location
    Pittsburgh, PA
    My 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
    24,806
    Mentioned
    4 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by madpogue View Post
    "8/9" usu. means it'll work on either one (click-stop spacing is the same, or close enough for "government work..."), but cable tension and high/low limit are presumed to be set correnctly on an 8-er that one click-stop just won't be used.
    I don't think that's correct as 8 and 9-speed cassette spacing are not the same. What the shifters refer to is that they will work with 8 or 9-speed rear derailleurs. The 7700-series was 9-speed Dura Ace so the shifter index spacing is for 9-speed.

Posting Permissions

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