Advertise on Bikeforums.net



User Tag List

Results 1 to 9 of 9
  1. #1
    Senior Member
    Join Date
    Mar 2008
    Posts
    101
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    question about triple crank

    Hello fella's,
    I currently have an older trek road bike with indexed downtube shifters. I've been doing some touring on this bike and now want to put a triple crank on it. I've got a new long cage rear derailluer, the correct bottom bracket, and a sugino triple crank, my question is do I need a new front derailluer as well? the current set-up on the bike is a double crankset.

    any help would be appreciated, thanks in advance.

  2. #2
    on your left.
    Join Date
    Nov 2007
    Location
    Blacksburg, VA
    My Bikes
    Scott SUB 30, Backtrax MTB
    Posts
    1,802
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    hm...i'm might get this wrong, but i'll take a shot at it. since it's indexed, all you'll need is a new shifter. I THINK. it's possble that the front derailleur was just made for two chainrings, but i'm willing to bet it can be made to work with a triple. if not, i think you could go friction shifting and definitly make it work.
    Quote Originally Posted by caloso View Post
    I learned this the hard way. They say that experience is the best teacher, but I would have been preferred to just read about it on the internet.

  3. #3
    Senior Member
    Join Date
    Jul 2006
    Location
    Dover, NH USA
    My Bikes
    1986 Bridgestone 500, 1981 Motobecane Super Mirage
    Posts
    245
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    You will likely need a new front derailleur as well, to handle the larger difference between the front cranks. This would depend on the model of your existing front derailleur.

    Depending on the cranks, you could keep the double and swap the chainrings to a smaller size. Moving from say, a 42/52 to a 34/48 would offer a much lower gear for climbing. Unfortunately this option is probably no cheaper than a larger capacity front derailleur.

  4. #4
    Your mom
    Join Date
    Aug 2006
    Posts
    2,546
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    You would also want a triple FD for the profile. You could probably shift a triple crank with a double FD, but it wouldn't work so well. Triple FDs have extra room where they need it and lumps and bumps to push your chain in the right places.

  5. #5
    Senior Member
    Join Date
    Feb 2005
    Location
    Oklahoma
    My Bikes
    Trek 5500, Colnago C-50
    Posts
    9,183
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    You will probably need a new front derailleur, of course you could try the old one.
    I doubt that you need a new front shifter, all you really need is a friction shifter for the front. Does the old shifter actually have clickstops? If so, how many?

    Al

  6. #6
    Senior Member
    Join Date
    Mar 2008
    Posts
    101
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Hey thanks guys,
    the shifter that I have now is an older shimano 600 shifter that can go friction. The crank i'm using is a triple touring crank is a 46-36-26 if this helps.

  7. #7
    Senior Member
    Join Date
    Jun 2007
    Posts
    1,516
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    I would try it. You will need to lower the FD on the seat tube. If you have a problem it will likely be that the chain drops when shifting to the small ring. Triples have a deeper inside plate so if you get a new one be sure it will clear your middle ring when going to the big ring. For example, a 10 sp Ultegra made for a 39 tooth middle ring will not work well with a 9sp Ultegra crank with 42t middle ring. Don't ask....

  8. #8
    Senior Member
    Join Date
    Jun 2003
    Location
    Iowa
    Posts
    97
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    a double fd doesn't have enough capacity to clear the chain on the small ring. it's just not long enough even if you lower it as far as you can. it also isn't designed to travel far enough in and out. just get a new fd. they're cheap anyway.

  9. #9
    Fred-ish rogerstg's Avatar
    Join Date
    Aug 2007
    Location
    Rhode Island
    Posts
    1,801
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I would try it first since you've got nothing to lose. The profile of the triple vs double is only important if using indexed shifters. Capacity is the most likely problem, but there may be enough room, depending on the bike's geometry.

Posting Permissions

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