Advertise on Bikeforums.net



User Tag List

Results 1 to 12 of 12
  1. #1
    just going for a ride... lbear's Avatar
    Join Date
    Jan 2008
    Location
    Hillsboro, Oregon
    My Bikes
    LeMond Sarthe, OCR A1, OCR 2, Cypress DX
    Posts
    584
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    105 STI with Shimano SLX rear Derailleur

    I am building a Soma Double Cross with 105 STI and a compact double up front. I was going with a 12-27 10 speed cassette to begin with, since it will be a commuter. If I ever want to tour I thought being able to put on a 12-34 might be nice. So before I buy the RD is there any down side to putting on a Shimano SLX instead of a 105 rear derailleur? This would allow me to have a commuter wheelset and a touring wheelset with different ratios.
    2011 Soma Double Cross
    2008 Lemond Sarthe
    2008 Giant OCR A1

  2. #2
    Senior Member
    Join Date
    Feb 2005
    Location
    Oklahoma
    My Bikes
    Trek 5500, Colnago C-50
    Posts
    9,024
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    You will need a 9-speed rear mountain derailleur to work with your STI shifters. Shimano 10-speed mountain type rear derailleurs have a new actuation ratio to work with their new 10-speed mountain shifter cable pull. Be sure to get a "high normal" type RD so that the shifters work the same way as with the road derailleur. A "low normal" RD would make the shifter work backwards which is OK but most road riders don't like the change.

  3. #3
    Senior Member
    Join Date
    Oct 2007
    Location
    West Yorkshire, United Kingdom
    Posts
    3,137
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(s)
    Why not just use a GS model of the 5700 RD?

  4. #4
    just going for a ride... lbear's Avatar
    Join Date
    Jan 2008
    Location
    Hillsboro, Oregon
    My Bikes
    LeMond Sarthe, OCR A1, OCR 2, Cypress DX
    Posts
    584
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    The Maximum Sprocket of the GS is only 28 like the SS. I need more Max Sprocket (34 or more)not more Total Capacity. The TC of a 12-34 with a compact crank (50-34)is only 28.
    2011 Soma Double Cross
    2008 Lemond Sarthe
    2008 Giant OCR A1

  5. #5
    Senior Member
    Join Date
    Oct 2007
    Location
    West Yorkshire, United Kingdom
    Posts
    3,137
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(s)
    Thought you would say that, I am using a 5700 GS with a 12-32, which is more than enough gears, not sure I would need the 34 unless I was going vertical.

  6. #6
    just going for a ride... lbear's Avatar
    Join Date
    Jan 2008
    Location
    Hillsboro, Oregon
    My Bikes
    LeMond Sarthe, OCR A1, OCR 2, Cypress DX
    Posts
    584
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    So your 5700 works on a 12-32? Shimano says Maximum is 28. I am building this for someone else. He had mention he might want to do some light touring. So I wanted to gear it for some vertical and added weight.
    2011 Soma Double Cross
    2008 Lemond Sarthe
    2008 Giant OCR A1

  7. #7
    Senior Member
    Join Date
    Oct 2007
    Location
    West Yorkshire, United Kingdom
    Posts
    3,137
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(s)
    re-checked, am using a 5700 compact crank, and 5700 GS RD with a SRAM 11-32 10 speed cassette, all works fine together.

    This setup needs a 39t capacity, with is the max the 5700 GS can take (the 5700 SS is 33t)

    Have been using this for working out the max t capacity needed http://home.earthlink.net/~mike.sherman/shift.html

  8. #8
    just going for a ride... lbear's Avatar
    Join Date
    Jan 2008
    Location
    Hillsboro, Oregon
    My Bikes
    LeMond Sarthe, OCR A1, OCR 2, Cypress DX
    Posts
    584
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Sorry bad math.
    2011 Soma Double Cross
    2008 Lemond Sarthe
    2008 Giant OCR A1

  9. #9
    biked well well biked's Avatar
    Join Date
    Jul 2005
    Posts
    6,780
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    There's no set-in-stone maximum cog compatibility with any rear derailleur. The exact position of the derailleur hanger relative to the rear axle will vary some, and that will affect the maximum cog size you can use without the upper derailleur pulley hitting the largest cog. Shimano's specs on this are known to be conservative, and again, are really only an educated guess.

    I recently decided I wanted to use a SRAM Apex-like drivetrain on my "day touring" bike, but had mostly Shimano parts on hand and for the most part prefer Shimano over SRAM anyway. So I came up with what I call a "Shimapex" group. I used Shimano 105 shifters, 105 compact double crankset (50/34), 105 front derailleur, Shimano "trekking" LX rear derailleur ("9 speed" with an official max. cog compatibility of 32t), ten speed 12 x 32 SRAM cassette, and 10 speed SRAM chain. I'm loving this drivetrain, it gives me the kind of low gear I need with the simplicity and smoothness of double shifting up front. We've sold quite a few bikes equipped with SRAM Apex, and have retrofitted quite a few bikes with it as well, and for some applications it is just awesome IMO. I'm certainly enjoying my "Shimapex" setup.


  10. #10
    just going for a ride... lbear's Avatar
    Join Date
    Jan 2008
    Location
    Hillsboro, Oregon
    My Bikes
    LeMond Sarthe, OCR A1, OCR 2, Cypress DX
    Posts
    584
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    So you use a "9 speed" rear derailleur with a ten speed cassette??
    2011 Soma Double Cross
    2008 Lemond Sarthe
    2008 Giant OCR A1

  11. #11
    biked well well biked's Avatar
    Join Date
    Jul 2005
    Posts
    6,780
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by lbear View Post
    So you use a "9 speed" rear derailleur with a ten speed cassette??
    Yes, as Al1943 mentioned earlier in the thread, if you use a Shimano mountain bike derailleur with your 10 speed drivetrain (including 10 speed Shimano road shifters), you can't use the new "10 speed" Shimano mountain bike derailleurs. Shimano uses a different cable pull ratio on the 10 speed mountain bike derailleurs/shifters, the new system is called "Dyna Sys." The cable pull ratio of all other index-compatible Shimano shifters/rear derailleurs is the same, road or mountain, with the one exception being 8 speed and earlier Dura Ace. And now Dyna Sys is different, too. So yeah, just use any Shimano mountain bike derailleur you like with your road shifters except a 10 speed Dyna Sys model.

  12. #12
    just going for a ride... lbear's Avatar
    Join Date
    Jan 2008
    Location
    Hillsboro, Oregon
    My Bikes
    LeMond Sarthe, OCR A1, OCR 2, Cypress DX
    Posts
    584
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Super, thanks for the help.
    2011 Soma Double Cross
    2008 Lemond Sarthe
    2008 Giant OCR A1

Posting Permissions

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