Lowest gearing for double?

Discussion in 'Cycling Equipment' started by lostmyshape, Dec 5, 2003.

  1. lostmyshape

    lostmyshape New Member

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    i'm putting together a winter beater for the cold, wet months. it's pretty hilly here in pittsburgh, but i want to stick to a double (plus i already have a 105 double crank laying around)...

    what's the lowest gearing that i can use on a 105 double with a short cage rear derailluer? 39x27? i can't get a smaller ring on that crank, can i?

    i'm also curious: does anyone have any experience/opinion on the newer compact cranks (like the 50/34 FSA Carbon Compact)? anyone make a cheaper version of this? the FSA is a little expensive for me right now...

    thanks!
     
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  2. boudreaux

    boudreaux New Member

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    Smallest ring on a shimano 130 BDC crank is 38.Cage length has nothing to do with large cog.Current shimano 9 speed RDs are speced for 27 teeth regardless of cage length,and will usually handle a 30. For a bigger cog,use a mtb cassette and RD. There are plenty of 110 BCD cranks around as that was common on older MTB stuff. Check cranks at www.branfordbike.com for current options. There are also Current Sugino 110/74 mtb cranks and the granny ring can be ditched of you don't want a triple.
     
  3. sea

    sea New Member

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    I used a 105 with a 38 tooth front & a 27 rear and was told by two bike shops that that was the lowest setup 105 could handle.
     
  4. boudreaux

    boudreaux New Member

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    That's just hooey,and regurgitaing Shimano drivel concerning large cog spec. Sheldon Brown sellls a custom 30 cog cassette and it works with any current Shimano RD.
     
  5. sea

    sea New Member

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    A little politeness would be nice, boudreaux.
     
  6. lostmyshape

    lostmyshape New Member

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    Thanks guys,

    just check sheldon brown's site and they say that a 105 double rear can handle up to a 28... i guess that means the best i can do is a 38-28... not too bad for the hills. i think i can handle it. although it's tough to find a cassette that has a 28 big cog. harris cyclery has some, but they're a bit pricey.

    they also recently put up a link for "110mm BCD Cyclocross Double", but when you click on it you just get a "coming soon". after reading some stuff that leonard zinn has said about compact cranks, i'm really interested in them.

    thanks again for the info.
     
  7. boudreaux

    boudreaux New Member

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    Well, actually ,even Sheldon has the occasional brainfart. In most cases Shimano RDs speced for a 27 handle a 30, and I have even heard of some cases using a 32. check sheldons custom road cassettes with a 30 large cog and see what the recommendation is for a RD with them.
     
  8. pudster

    pudster New Member

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    It can also depend on the rear hanger for the derailluer. Some hangers are shorter than others. Most road frames use a shorter hanger than say mtn frames. With a short hanger you probably won't be able to run a cog that is much bigger than a 27. You can turn your angle adjust screw but it won't be long enough. Sometimes adding a longer screw will help though. Most bike frames should run the longer hanger length for clearance between the derailluer mount and the quick release when taking the wheel out.
     
  9. pudster

    pudster New Member

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    It can also depend on the rear hanger for the derailluer. Some hangers are shorter than others. Most road frames use a shorter hanger than say mtn frames. With a short hanger you probably won't be able to run a cog that is much bigger than a 27. You can turn your angle adjust screw but it won't be long enough. Sometimes adding a longer screw will help though. Most bike frames should run the longer hanger length for clearance between the derailluer mount and the quick release when taking the wheel out.
     
  10. pj_s

    pj_s New Member

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    looks like I'll be going to the italian/french alps again this year to cycle the fausto coppi. Decided that the 39-28 is not a low enough combination. So have ordered a stronglight Z-light compact crankset with a a 34-50 combination. Stronglight also has decently priced Gran Frondo and impact cranksets at about 110 euro (which I won't be getting, as these don't come with 180mm cranks).

    pj
     
  11. boudreaux

    boudreaux New Member

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    Yes in most cases you can urn bigger than a 27. The 'angle screw' has nothing to to with the ability to shift to the bigger cog. It adjust top pulley clearance,and a longer one can be substituted.
     
  12. pudster

    pudster New Member

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    So I guess what you are saying then is the angle adjust srew does not have anything to do with the derailluer going to a larger cog on the back? So the noise that I here when my jockey pulley is running on the largest cassette cog does not have anything to do with the hanger length and the B srew? Could you please explain it to me. I guess I don't know what I am talking about, sorry!
     
  13. rek

    rek New Member

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  14. boudreaux

    boudreaux New Member

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    The ability to shift to the large cog has nothing to do with the 'b' screw. That ability is in the derailer parallelogram. The 'b' screw allows adjustment of the pulley relative to the cog,after the shift has been made.
     
  15. pudster

    pudster New Member

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    I guess that I am talking if it works. If you can not get the cog and jockey pulley to stop making noise then it does not work. I know the derailluer will go over far enough.
     
  16. boudreaux

    boudreaux New Member

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    One can use a longer screw or tighter chain.
     
  17. pudster

    pudster New Member

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    mmm. does not always work.
     
  18. el Ingles

    el Ingles New Member

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    Have used a 28 with an ultegra and it works fine , about cranks --try Stronglight , they make compact cranks ( Gran Fondo ) that are very popular in Europe , France and Italy in particular and give 50 - 36 and 48 - 34 combination ... ..but check that you can lower the front mech far enough BEFORE investing your cash ( should get cheaper if the dollar stops acting like a submarine )
     
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