Lowest possible granny gear (crisp shifting) with road STI's

Discussion in 'Cycling Equipment' started by Dax Ford, Feb 14, 2005.

  1. Dax Ford

    Dax Ford New Member

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    What is the best way to get a 24T granny gear on a STI shifted road bike?

    I was thinking of doing this...

    1. DA 7700 triple front derailleur
    2. 105 triple crank with octalink BB
    3. 53/39/24 rings (middle ring would have pins on both sides)
    4. XT rear derailleur (for extra wrap capacity)...plus I already have one.

    I was thinking it would be better to shift from a 39T ring rather than a 42T ring when going back and forth from the granny to middle. DA 7700 front derailleur lets me use 14T jump between outer and middle.

    My question: Are these the best parts to make 24T granny work? Or should I be using 52/38 rings?

    Who makes a nice matched 53/39 ring set that has pins on both sides of middle ring for triple use? I'm thinking FSA or TA?

    Will I need a third eye chain watcher with a 39T middle ring?
     
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  2. Randybaker99

    Randybaker99 New Member

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    Do you live on top of Mt. Washington? Where do you live, that you need more than 1:1 gearing? I want to come visit!

    I would have thought that a 30T in the front and a 28T in the back is enough to climb any paved surface out there.
     
  3. Dax Ford

    Dax Ford New Member

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    I used to live in Malden (right next door to you)......greater Boston is flat compared to Sierra Nevada. You should come out to California or Colorado if you want some real climbing...besides I like to tour on my bike.

    I heard Sheldon Brown was in this forum.
     
  4. Randybaker99

    Randybaker99 New Member

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    Hah! Small world.

    So what is the grade of the road you are going to climb with this bike?
     
  5. Dax Ford

    Dax Ford New Member

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    No joke........there are signs marked 19% grade around here.

    I may not need a 24T, but I want to set up my bike with the capability to go to 24T should I need to. I ride a double right now.

    BTW, I used to go to Tufts. I never thought I would need a triple till I moved here.
     
  6. Randybaker99

    Randybaker99 New Member

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    I live 2 blocks from Tufts, but I'm not a student there.
     
  7. boudreaux

    boudreaux New Member

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    You may well be kidding yourself about crisp when it comes to a 24 granny and either a 38 or 39. consider yourself lucky if it shifts at all with STI. If you need a 24,do you really need a 53? consider a whole different crankset with a 48 or 50 big ring, and a 34 or 36 middle.
     
  8. Dax Ford

    Dax Ford New Member

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    Let me rephrase the question.......How can I get the best possible shifting to a 24T granny ring as well as other rings using STI shifters? Or Should I just give up this idea and limit myself to a 26T or 28T?


    I don't want or need the 53. I just want to know what combo will shift the best?

    I'm thinking the DA front derailleur will help because it lets me use a 39T instead of a 42T. I figure any shift to a small ring will be better if it comes from a 39T because the jump will be smaller.

    Then again I could use a 105 front derailleur and 48/38/24 combo, but is that going to be any better?(Considering now that rings are mismatched to radius on 105 derailleur)
     
  9. Dax Ford

    Dax Ford New Member

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    So you think a 48/34/24 would shift better?

    That would be a 110 BCD triple......So I should probably use DA FD becasue of the 14T difference between middle and outer rings.

    I just want the best shifting combination I can get that has a 24T.
     
  10. boudreaux

    boudreaux New Member

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    I used a 105 9 speed triple FD with 46/36/26 rings and sti and no issues. No reason it wouldn't work with a 48/38. Now turn off the shout button.
     
  11. Dax Ford

    Dax Ford New Member

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    Well I just looked at the gear reduction charts.....26T is plenty considering it is a 50% change from a 39T.

    I just wonder how well that 53/39/26 combo would work....obviously shifting under load won't be great. But I figure as long as I shift cassette properly in combination with chainring shifts ......it shouldn't be too bad right?
     
  12. boudreaux

    boudreaux New Member

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    The 26 gets used with shimano triples. You obviously aren't racing it,so it's possible to finess the shift.
     
  13. maxxevv

    maxxevv New Member

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    If you really want a 30+T granny gear, get an MTB XT Rear Derailer... It works like a gem.
     
  14. boudreaux

    boudreaux New Member

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    D'oh?? and what's that got to do with front shifting.And if you are thinking 30 + big rear cog consider the crappy big jumps between cogs. With a triple front and small rings you get to retain close ratios in the back.
     
  15. Dax Ford

    Dax Ford New Member

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    I already have one. I don't really want the big gaps of a mtn cassette. Check these gaps= 12, 14, 16, 18, 20, 23, 26, 30, 34 (that a 12-34 XT cassette)

    I was thinking of using a 13-30 custom cassette 13, 14, 15, 17, 19, 21, 24, 27, 30 or just a 12-27 (12, 13, 14, 15, 17, 19, 21, 23, 27).

    Best cassette I could make starting with mtn cassette would be 12, 13, 14, 16, 18, 20, 24, 28, 32 (basically a 11-32 with 11T and 12T removed and replaced with top position 12T and 13T)

    Right now a 26T would be workable if the DA deralleur could handle a 38T chainring in the middle. DA 7700 specs 14T differenece between Outer and middle rings.

    Honestly a 53/39/28 would give me a good range and minimize overlap. I would mind trying the 26T if the 38T would shift nice.

    I have no experience with triples, so I don't know how finicky the derailleurs are. The only reason I was keeping it 53/39 was to minimize any shifting problems.
     
  16. meb

    meb New Member

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    I've known many recumbent riders to get a stock 105 fder to work on 28T big to small ring differences, one even got 30T. Haven't heard about anyone jumping that much with DA, my suspicion is probably only 26T differences with the DA (and that is beyond the official spec).

    The shifts are going to be clunky rough, but the fder will shift rings.
     
  17. neil0502

    neil0502 New Member

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    Don't know if you ever made a decision on this, but . . .

    On my Cannondale T2000 tourer, I've got an Ultegra crankset with 24/38/48 and a 105 FD. Out back is an XTR der.

    Works just fine.
     
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