Advertise on Bikeforums.net



User Tag List

Results 1 to 5 of 5
  1. #1
    DvB
    DvB is offline
    Senior Member
    Join Date
    Aug 2005
    Posts
    58
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Shimano Sora: indexed front triple to friction front double?

    I've done a lot of searching on this topic, but have found no answers. If a thread already exists, please forgive me. (And provide the link!)

    I'd like to swap out the heavy triple crank on my girlfriend's roadbike with a nicer, lighter compact double. I'm mechanically experienced and can do the BB and crank swap no problem. Only issue is the front brifter (Shimano Sora). It's indexed for a triple, and I don't know if it can be modified to be either: (a) friction, which I'd prefer; or (b) indexed for a double. Anyone know?

    Knowing Shimano, I'm guessing the answer is no, the shifter can't be modified. If this is indeed the case, has anyone used the triple brifter with a double crank successfully? Is it possible, through proper set-screw adjustment and cable tensioning, to use only two of the brifter's three index positions?

    Thanks a lot in advance for any assistance.

    --DvB

  2. #2
    B-b-b-b-b-b-bicicle Rider orange leader's Avatar
    Join Date
    Apr 2005
    Location
    Northfield, MN
    My Bikes
    1997, stumpjumper S-works hardtail, Medici, Giant allegre (track dropouts and fixed gear), Columbia twosome, schwinn twinn, '67 raleigh 5 speed internal hub, Old triumph 3 speed, old BSA 3-speed, schwinn Racer 2spd kickback, Broken raysport criteriu
    Posts
    739
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I haven't tried it with brifters yet (none of my bikes are that up to date) but I would think you could just set the derailleur's low side set screw so as to disallow the throwing of the chain down to the granny range. Or disallow the throwing to the high side, whichever works best with the chain rings you opt for. you may also be able to adjust your crank position depending on what type of bottom bracket you opt for, some BBs are more adjustable than others.

    I've done similar things, in the past and always find myself trying to shift into gears that I know aren't there. It's just habit, the bike doesn't do it, because i adjusted those gears out, but the cable will dangle slack until I figure out what I subconciuosly tried to do.

    Good luck, I'd say it's doable.
    Rudimentum mendum menda
    Iudicium mendiosus
    Judicium per erratum
    Judicium et erratum!

  3. #3
    THIS SPACE FOR RENT
    Join Date
    Jan 2006
    Posts
    2,849
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Just hook it up, set the limit screws, and see how it runs. Triples aren't really "indexed" in the way a rear D is, you actually do use the index positions to adjust where the FD is to prevent the chain from rubbing just like you do with friction shifters. I can't 100% promise it's going to work, but I'm betting it will shift from low to high with three or four clicks, and give you usable positions down one click from that and up one click from the low position.

    Also, check out swap meets and maybe even put a WTB in your sig, sora brifters are pretty common components in people's parts bins.
    "I don't buy new frames, it just encourages them."

    -T.G.

  4. #4
    Gone, but not forgotten Sheldon Brown's Avatar
    Join Date
    Jul 2002
    Location
    Newtonville, Massachusetts
    My Bikes
    See: http://sheldonbrown.org/bicycles
    Posts
    2,301
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by DvB
    I've done a lot of searching on this topic, but have found no answers. If a thread already exists, please forgive me. (And provide the link!)

    I'd like to swap out the heavy triple crank on my girlfriend's roadbike with a nicer, lighter compact double. I'm mechanically experienced and can do the BB and crank swap no problem. Only issue is the front brifter (Shimano Sora). It's indexed for a triple, and I don't know if it can be modified to be either: (a) friction, which I'd prefer; or (b) indexed for a double. Anyone know?
    It will work fine. Any shifter works for a front double, it's only triples that are fussy 'cause they index the middle ring. (On a double, the "indexing" is provided by the derailer's limit stop screws.)

    Sheldon "Sora Fan" Brown
    Code:
    +------------------------------------------+
    |  To have doubted one's first principles  |
    |  is the mark of a civilized man.         |
    |                -- Oliver Wendell Holmes  |
    +------------------------------------------+
    [COLOR=blue][CENTER][b]Harris Cyclery, West Newton, Massachusetts[/b]
    Phone 617-244-9772, FAX 617-244-1041
    [URL= http://harriscyclery.com] http://harriscyclery.com[/URL]
    Hard-to-find parts shipped Worldwide
    [URL=http://captainbike.com]http://captainbike.com[/URL]
    Useful articles about bicycles and cycling
    [URL=http://sheldonbrown.com]http://sheldonbrown.com[/URL] [/CENTER] [/COLOR]

  5. #5
    DvB
    DvB is offline
    Senior Member
    Join Date
    Aug 2005
    Posts
    58
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Sheldon Brown
    It will work fine. Any shifter works for a front double, it's only triples that are fussy 'cause they index the middle ring. (On a double, the "indexing" is provided by the derailer's limit stop screws.)

    Sheldon "Sora Fan" Brown
    Code:
    +------------------------------------------+
    |  To have doubted one's first principles  |
    |  is the mark of a civilized man.         |
    |                -- Oliver Wendell Holmes  |
    +------------------------------------------+
    Thanks for the input, everyone. I know it will "work," i.e., the setup will allow shifting from big ring to small and vice-versa. I was just concerned about how well it would work. I could see the setup being quite annoying if the spacing between the two chainrings on the new double crank didn't quite match the two corresponding indexed positions on the old triple shifter. (I'll still never understand for the life of me why anyone would want indexing for the front changer -- whether the crank is a double or a triple.)

    I will say that despite being a little annoyed at Shimano right now, the Sora stuff works really well (especially given its low-on-the-totem-pole spot in Shimano's lineup). Easy to work on, smooth, and so far very reliable.

    Good suggestion to scour parts bins and message boards -- I think I'll just look for a cheap double brifter to replace the old triple.

Posting Permissions

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