you people out there riding double or tripple?

Discussion in 'Cycling Equipment' started by Kaboom, Nov 11, 2003.

  1. thotdoc

    thotdoc New Member

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    A compact double is less wide, thus a more natural spinning action.

    A compact double can be built with a close ratio set that approximates a triple, (eg, a 2.3 gain ratio with a 34X29 rather than 2.1 on 39X26) with 15 or 16 usable ratios.

    People's weight is a moot point. The game for most people is to build the lightest, most safe, efficient and relaible, and aerodynamic bike.

    A compact double built the way mine is has those characteristics. My 58cm steel/ carbon frame and components weighs 6444gms or 14.02#. I got there by understanding the safest/lightest/most aerodnamic way to evaluate and select each component.

    I looked at triples and doubles, having ridden both. I ride where there is only one real flat ride. Every ride is over hills and mountains, so gain ratios are important. My conclusion after studying the issue, was the following:
    A triple ring is heavier. It has a less efficient spinning action. It is less aerodynamic. A compact double has the advantage in the 3 areas most important in bikes: weight, efficiency and aerodynamics. A compact double can approximate a triple so closely, in terms of gain ratios, that the cycling costs of the triple do not make it a sensible choice for me.

    Perhaps you have other criteria you find more important than efficiency, weight and aerodynamics.

    G
     


  2. el Ingles

    el Ingles New Member

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    Try riding the mountains in Europe during July and August , the Ventoux and the Angliru for example , even the pros used the 30 for the latter and the former killed Tommy Simpson ( pray it´s not a hot day ) .
    ¿ Ever hear the expresion ' all mouth and no trousers `? :p
     
  3. labicci

    labicci New Member

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    If compact doubles are so good, why Campagnolo and Shimano bother to produce triple version for their Record and DuraAce crankset ?

    For a same gear ratio, a chain runs through the chain rings and cogs of a compact system at a smaller radius, i.e. further away from a straight line which has the greatest radius (a radius of infinity). Which system do you think is more efficient ?

    And a chainline which is parallel to the bike is the most efficient. Isn't the chainline of the lowest gear of a triple system closer to parallel than the chainline of the lowest gear of a double system ?

    How about durability ? Isn't a compact system with fewer teeth to spread the load and with the chain having to swivel more around its rivets wears faster ?

    And talking about aerodynamics why not consider installing smaller wheels which has more significant effect than the chainrings ?

    And afterall why not consider a triple system being better than a double system ? When more and more gears are put into the rear and most people consider this as an upgrade, why not one more chainring at the front not an upgrade ? Isn't it the way to go to reduce the chainline angle increased by having more cogs in the rear ? Is it because having one more chainring means having greater chance of making error in shifting ?

    Like to hear the thoughts from others.

    L.B.
     
  4. thotdoc

    thotdoc New Member

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    Great questions. I would like to hear from others also, with hard data and good questions. I don't think this setup will go away. It's just too sweet.

    RE 1. This is a marketing issue. They will respond if the market is there.

    Re 2. This answer can be derived mathematically. I'm a scientist by professsion, so I'd want to see the math. IMHO I don't think the difference here is a difference that makes a difference. But, there is an answer.

    Re 3 I don't know that any differences, either way here , would make much difference. Without going outside to look at my bikes and trying to measure them (is someone willing to do this and then do the math) to show that that the difference, if it exists, makes a difference.

    Re 4. IMHO not a difference that makes a difference, to many other variable effect this.

    Re 5 Questioned and answered hundreds of times in favor of 700s unless your frame calls for 650s.

    Re 6 Going to 10's is considered by many a marketing issue, a race between S & C, not a performance issue. Fewer errors in shifting IMHO come with fewer options.

    I don't KNOW which is best. I did my homework and got the compact double. I'll alert FSA to this thread and let them answer the questions we develop, if they will.

    Send in the questions and hard data.

    G
     
  5. drewski

    drewski New Member

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    Assuming
    1) that the drivetrains are designed so that the mid-point of the most-separated chainrings is aligned with the middle of the freewheel and
    2) that in a given system (C or S) any 9-speed chainrings/cogs are uniformly separated (i.e. distance from 1-2 and 2-3 on a triple is identical and equivalent to the distance from 1-2 on a double, and freewheel cogs. let's call this W), you can see that the inner ring on a triple (1*W) is further inboard vs. the double (0.5*W) compared to the mid-point of the most separated chainrings.

    Given that the innermost cog on the free-wheel is 4 cogs from the center (4*W) and further inboard than either inner chainring, the straightest resulting chainline will be the one that minimizes the difference between the outer cog and the outer ring.

    For the double this difference is 3.5*W and for the triple 3*W, so the triple's inner*inner comob is closer to parallel, the difference being equivalent to the differenct chainlines by shifting 0.5 cogs on the freewheel.

    I don't have a study in front of me, but I'm pretty sure that it's been shown that with equivalent use the inner (smaller) chainrings and inner cogs on a freewheel will wear faster than the outer ones.
     
  6. ProfTournesol

    ProfTournesol New Member

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    sorry to keep coming back to this, but doesn't it depend on the gearing required to maximise the efficiency of the rider on the bike. You need only look at ant technology driven sport to see that the best technological solution is not always the best solution as the human factor is often the bottom line.
     
  7. trinidoc

    trinidoc New Member

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    Double on my Vitus road bike
    Tiple on my Giant mountain bike
     
  8. trinidoc

    trinidoc New Member

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    Double on my Vitus road bike
    Tiple on my Giant mountain bike
     
  9. thotdoc

    thotdoc New Member

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    Michael,

    I agree with you.

    And, I'm trying to see if there is any scientific or experencial data out there re this 2 vs 3.

    So far not much. Things become derivative. We've moved the discussion from pedaling efficiency re the 2 vs 3 on the knees (2 better) to discussion on chain efficiency. I'm not sure that chain efficiency differences are important. But, thinking of chain movements brings up a most important variable. The ease of movement between gear ratios when you haven't planned well. At least it is important for me as I ride in hills constantly. I find it easier to move between chain rings on a 2 ring when I've really made a mistake and need to drop quickly. Going from big to smallest and shifting down within the casette is a great way to drop the chain. Maybe it's different for others.

    The data is out there, scientific and experiential.

    Whose got it? I don't have data. Just experiences, and all experiences ar equal. Then, all data can be made irrelevent by individual experiences, as you point out.

    Perhaps there is no truth here. Just, what works best for you.

    G
     
  10. drewski

    drewski New Member

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    try the
    jump stop by n-gear. i haven't had a dropped chain since i put these on my bikes (knock on wood).

    nick seems really customer service oriented (he sends you the part before you pay and you don't pay unless you're happy) and the $10 price which includes shipping is pretty fair, imho.

    of course, it weighs about an ounce so gram counters may not use it!
     
  11. Truepurple

    Truepurple New Member

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    If I understand the question right, triple because thats what my bike came with. Don't most bikes come with triple?
     
  12. awtye

    awtye New Member

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    I try to copy my body
    One ring at the front, one at the back, any more is a waste!

    ha ha

    Angus
     
  13. ProfTournesol

    ProfTournesol New Member

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    so then triples are necessary for women then Angus?
     
  14. bfra1

    bfra1 New Member

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    Road : Double
    Mountain: Triple
     
  15. jgatts

    jgatts New Member

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    Damn straight. And coasting is for wimps, but I'm not sure of the anatomical implications there.

    --Josh
     
  16. awtye

    awtye New Member

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    Roger that, spinyourtitsoff!
     
  17. retrogeek

    retrogeek New Member

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    I use a triple chainring to get a more even spread across the gearing range, rather than only using it for beating big hills. 90% of the time I will just use an 12-21 rear cog-set and adjust the gearing range by swaping out various combinations of front chainrings.

    For the flats and rolling hills I will use a 50-42-32 front chainring setup for a close and even spread of gears, at 44 I can no longer push a 53/12 for any great length of time so I don't even bother to try any more, and a 32/21 is plenty low enough for this purpose.

    For bigger hills I will use a 53-39-30 front chainring setup (53 for the downhills only), as a 30/21 is approximately equal to a 39/27-28. If I need anything lower geared than this (which I seldom do) I will then put on an 12-23 rear cogset, as a 30-23 is approximately equal to a 39/30.

    I use a bar-end shifter for the front derailier since I have never felt comfortable with Ergopower or Dual Control triple front shifters, it's just a personal preference.
     
  18. jgatts

    jgatts New Member

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    That sounds like a good strategy. Triples do let you use a nice tight cluster while still getting decent range. The main thing that I don't like about them is sloppy indexed shifting on the front. I've been toying with the idea of doing something similar to what you've done on my touring bike (which is my only triple): a bar end shifter for the front, with STI for the rear. This should give the best of both worlds: non-indexed infinite adjustibility on the front, with quick shifts on the rear, which is where most of the shifting happens anyway.
     
  19. ProfTournesol

    ProfTournesol New Member

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    if you get a chance, try Campag. It has microadjust on the front derailler, a really useful feature with triples
     
  20. jgatts

    jgatts New Member

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    I love Campy, but I sometimes need to run big MTB cassettes on the tourer, larger than Campy rear derailleurs can handle. You're right, though, Ergo would be a great way to go for most triple owners. Shame there are so few bikes available with Campagnolo off the shelf.

    --Josh
     
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